preliminary hydrologic and hydraulic analyses · l:\projects\icicle and peshastin irrigation...

$: Preliminary Hydrologic and Hydraulic Analyses · L:\Projects\Icicle and Peshastin Irrigation Districts\Eightmile Lake Storage Restoration\Reports\Hydrology-Hydraulics - Existing\IPID$
June 2018 Eightmile Lake Storage Restoration Project

Preliminary Hydrologic and Hydraulic Analyses

Prepared for Icicle and Peshastin Irrigation Districts

L:\Projects\Icicle and Peshastin Irrigation Districts\Eightmile Lake Storage Restoration\Reports\Hydrology-Hydraulics - Existing\IPID - Eightmile Lake - Prel H and H Report - 2018_06_11_clean.docx

June 2018 Eightmile Lake Storage Restoration Project

Preliminary Hydrologic and Hydraulic Analyses

Prepared for Icicle and Peshastin Irrigation Districts P.O. Box 371 5594 Wescott Drive Cashmere, Washington 98815

Prepared by Anchor QEA, LLC 720 Olive Way, Suite 1900 Seattle, Washington 98101

Preliminary Hydrologic and Hydraulic Analyses i June 2018

TABLE OF CONTENTS 1 Introduction ................................................................................................................................ 1

1.1 Location and General Information ................................................................................................................ 1 1.2 Eightmile Lake Dam Emergency Declaration ............................................................................................ 3 1.3 Purpose ................................................................................................................................................................... 4

2 Site Description .......................................................................................................................... 6 2.1 Watershed Area ................................................................................................................................................... 6 2.2 Existing Reservoir Conditions ......................................................................................................................... 8

2.2.1 Dam and Embankment ...................................................................................................................... 8 2.2.2 Low-Level Outlet Pipeline and Gate ............................................................................................. 9 2.2.3 Overflow Channel to Eightmile Creek ...................................................................................... 10 2.2.4 Useable Storage Capacity ............................................................................................................. 10

3 Hydrologic Analysis ................................................................................................................. 13 3.1 Design Storm Selection .................................................................................................................................. 13

3.1.1 Identify Climatic Region ................................................................................................................. 13 3.1.2 Estimate Mean Annual Precipitation ......................................................................................... 13 3.1.3 Estimate L-Moment Statistics ...................................................................................................... 13 3.1.4 Calculate Mean At-Site Precipitation ........................................................................................ 14 3.1.5 Calculate Base Precipitation Values ........................................................................................... 14 3.1.6 Scaling Precipitation Estimates ................................................................................................... 15 3.1.7 Calculate Total Storm Precipitation ........................................................................................... 15 3.1.8 Calculate Peak Rainfall Intensity ................................................................................................. 16 3.1.9 Calculate Snowmelt Contribution .............................................................................................. 17 3.1.10 Calculate Design Storm Hyetograph ........................................................................................ 17

3.2 Hydrologic Rainfall Runoff Model ............................................................................................................. 18 3.2.1 Methodology ..................................................................................................................................... 18 3.2.2 Soil Characteristics and Land Cover .......................................................................................... 20 3.2.3 Land Cover, Curve Number, and Time of Concentration .................................................. 20 3.2.4 Estimated Inflow from Design Storm ........................................................................................ 22 3.2.5 Comparison to U.S. Geological Survey Methodology ........................................................ 22

4 Existing Dam Overflow and Freeboard Analyses ............................................................ 24 4.1 Existing Reservoir Operation ........................................................................................................................ 24 4.2 Current Operating Conditions ..................................................................................................................... 24

Preliminary Hydrologic and Hydraulic Analyses ii June 2018

4.3 Existing Overflow Analysis ............................................................................................................................ 25 4.4 Freeboard Analysis ........................................................................................................................................... 25

5 Dam Break Analysis ................................................................................................................ 28 5.1 Dam Break Geometry ..................................................................................................................................... 28 5.2 Downstream Flood Routing ......................................................................................................................... 30 5.3 Inundation Mapping ....................................................................................................................................... 31

6 Summary and Next Steps ..................................................................................................... 45

7 References ................................................................................................................................ 47

TABLES Table 2-1 Lake Volume Summary (From 2014 Forsgren Associates, Inc./Gravity Consulting,

LLC Study) .................................................................................................................................................... 11 Table 2-2 Lake Volume Summary (Based on Additional Data Collection) .......................................... 12 Table 3-1 Results of Precipitation Frequency Analysis ................................................................................. 14 Table 3-2 Total Precipitation for Design Storms ............................................................................................. 16 Table 3-3 Peak Storm Intensities for Design Storms ..................................................................................... 17 Table 3-4 Snowmelt Contribution for Design Storms .................................................................................. 17 Table 3-5 Subbasin Times of Concentration and Curve Number Values ............................................. 21 Table 3-6 Estimated Inflow from Design Storm .............................................................................................. 22 Table 4-1 Existing Conditions Step 8 Routing – Low-Level Outlet Starting Conditions ................ 25 Table 4-2 Freeboard Analysis – Low-Level Outlet Starting Conditions................................................. 26 Table 4-3 Freeboard Analysis – Flow Control Notch Starting Conditions ........................................... 27 Table 5-1 Approximate Maximum Water Depths and Widths for Overtopping Dam Breach

Downstream of Eightmile Lake .......................................................................................................... 32 Table 5-2 Approximate Maximum Water Depths and Widths for Normal-Pool Dam Breach

Downstream of Eightmile Lake .......................................................................................................... 33

FIGURES Figure 1-1 Location Map ................................................................................................................................................ 2 Figure 2-1 Eightmile Lake Drainage Basin .............................................................................................................. 7 Figure 3-1 Design Storm (Step 8) Hyetographs ................................................................................................ 18 Figure 3-2 HEC-HMS Subbasin Delineation ........................................................................................................ 19 Figure 3-3 Design Storm (Step 8) Inflow Hydrographs ................................................................................. 23 Figure 5-1 Inundation Area ........................................................................................................................................ 35

Preliminary Hydrologic and Hydraulic Analyses iii June 2018

Figure 5-2 Inundation Area ........................................................................................................................................ 36 Figure 5-3 Inundation Area ........................................................................................................................................ 37 Figure 5-4 Inundation Area ........................................................................................................................................ 38 Figure 5-5 Inundation Area ........................................................................................................................................ 39 Figure 5-6 Inundation Area ........................................................................................................................................ 40 Figure 5-7 Inundation Area ........................................................................................................................................ 41 Figure 5-8 Inundation Area ........................................................................................................................................ 42 Figure 5-9 Inundation Area ........................................................................................................................................ 43 Figure 5-10 Inundation Area ........................................................................................................................................ 44

APPENDICES Appendix A Ecology Dam Safety Office March 23, 2018 Letter Appendix B Precipitation Data Worksheets Appendix C Snowmelt Analysis Worksheets Appendix D HEC-HMS Results Appendix E Dam Break Worksheets Appendix F HEC-RAS Results

Preliminary Hydrologic and Hydraulic Analyses iv June 2018

ABBREVIATIONS cfs cubic feet per second CMP corrugated metal pipe CN curve number DEM digital elevation model DF design factor DSO Dam Safety Office Ecology Washington State Department of Ecology HEC-HMS Hydrologic Modeling System IDF Inflow Design Flood in inch IPID Icicle and Peshastin Irrigation Districts L-Cv site-specific coefficient used in DSO spreadsheet to calculate At-Site Mean

Precipitation. LiDAR Light Detection and Ranging L-Skew site-specific skew value used in DSO spreadsheet to calculate At-Site Mean

Precipitation. NAVD 88 North American Vertical Datum of 1988 NRCS National Resources Conservation Service PAR Person at Risk Pgds estimated 2-, 6-, or 24-hour precipitation for selected frequency Psd scaling precipitation for 2-, 6- or 24-hour index period RM river mile Technical Note 3 Dam Safety Guidelines Technical Note 3: Design Storm Construction USGS U.S. Geological Survey WSE water surface elevation

Preliminary Hydrologic and Hydraulic Analyses 1 June 2018

1 Introduction 1.1 Location and General Information Eightmile Lake is located in the Icicle Creek Subbasin on the east slopes of the Cascade Mountains approximately 10 miles west of the City of Leavenworth, Washington (see Figure 1-1). The lake is situated within Sections 32 and 33, T24N, R16E, and is within the Alpine Lakes Wilderness Area of the Okanogan-Wenatchee National Forest. Eightmile Lake is one of four lakes in the Alpine Lakes Wilderness Area managed by Icicle and Peshastin Irrigation Districts (IPID) as a storage reservoir to provide water supply for irrigation (Anchor QEA 2018a). A small dam and low-level outlet facilities were installed at the outlet of each lake in the early part of the twentieth century to allow IPID to capture and store runoff during the winter and spring for release during the late summer low flow period. The flows released from the IPID-managed lakes allow IPID to maintain diversions and meet instream flow obligations.

The existing facilities that control flow from Eightmile Lake to Eightmile Creek consist of a dam, a low-level outlet pipeline, and a slide gate that controls flow from the lake to the low-level outlet pipeline. The dam consists of a rock-masonry/concrete structure and an earthen embankment section that extends from the rock-masonry/concrete structure to the hillside north of the dam. Stop logs and plastic can be placed in a notch in the rock-masonry/concrete structure to control the water storage level in the lake.

The dam, outlet, and control gate at Eightmile Lake are in need of repair. The top of the embankment historically matched the top elevation on the wall of the rock-masonry/concrete structure. Stop logs were historically placed in the notch in the concrete portion of the dam up to the spillway crest (elevation ~4,671 feet North American Vertical Datum of 1988 [NAVD 88]) to allow the lake to fill to that elevation. The earthen embankment portion of the dam has eroded around the left side (looking downstream) of the rock-masonry/concrete structure. Consequently, the dam is not currently capable of impounding water to the full level for which it was designed and at which it historically operated. IPID can now only raise the water level to the top of the eroded embankment (elevation ~4,667 NAVD 88). This has reduced the active storage volume in the lake to 1,375 acre-feet (Anchor QEA 2018a). Eightmile Lake captures water from a 3,822-acre drainage basin and discharges surface water to Eightmile Creek, which is a tributary to Icicle Creek.

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Leavenworth Urban Growth AreaCascade Orchards IrrigationIPID Service AreaCountyIcicle Creek Watershed

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Figure 1-1Location Map

Preliminary Hydrologic and Hydraulic AnalysisEightmile Lake Storage Restoration Project

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Ecology Gage45B070 (RM 2.2)

Leavenworth National Fish

Hatchery(RM 2.7)

Cascade Orchards Irrigation Company Diversion (RM 4.5)

Leavenworth NationalFish Hatchery Diversion (RM 4.5)

USGS Gage12458000 (RM 5.8)

Icicle-Peshastin Irrigation District Diversion (RM 5.7)

City of Leavenworth Diversion (RM 5.5)

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Square LakeReservoir

Klonaqua LakesReservoir

EightmileLake

Reservoir

Colchuck LakeReservoir

Upper Snow LakeReservoir

Nada LakeReservoir

LowerSnow LakeReservoir

KINGCOUNTY

LANCOUNTY

CHELANCOUNTY

C

H ELAN COUNTY

CHELAN COUN T Y

KITTITA S COUNTY

KING COUNT Y

KITTITA

S COUNTY

KI T T ITAS CO U

Icicle Creek

Icicle Creek

A L P I N E L A K E S

W I L D E R N E S S

Project Location

Cashmere

Leavenworth

Peshastin

Sunnyslope

Wenatchee

DOUGLASCOUNTY


1.2 Eightmile Lake Dam Emergency Declaration Eightmile Lake Dam (Dam Safety Office [DSO] File No. CH45-0228) is more than 90-years-old and is in deteriorating condition. Two key concerns have made the need for improvement to facilities at the lake more urgent for IPID:

Low-Level Outlet Failure – The low-level outlet pipeline at the lake is approximately 300 feet long and consists of pipe that varies in size and composition. Recent work done to inspect the pipe has indicated that a portion of the pipe with a log-stave interior and concrete exterior is failing. The logs that formed the interior of the pipe have collapsed into the pipe and are plugging the pipe. IPID has noticed a significant decrease in the rate at which they can release water from the lake due to this failure. This limits IPID’s ability to draw down the lake and will significantly impact their ability to meet water supply needs the next time a drought emerges.

Jack Creek Fire – The August 2017 Jack Creek Fire burned trees and natural vegetation within the Eightmile Lake watershed down to the shoreline of the lake. This has created additional concerns of increased peak runoff into Eightmile Lake. IPID is concerned that increased inflow from a large storm event combined with debris piling up on the dam could put the existing dam at risk of failure.

Due to these concerns, IPID declared an emergency of Eightmile Lake Dam on March 13, 2018. As a follow-up to that emergency declaration, IPID has engaged in ongoing discussions with the Washington State Department of Ecology (Ecology) DSO and with local emergency response officials. IPID has also proposed to mobilize equipment and go up to the lake to make repairs and replace the existing facilities with new facilities designed to meet current DSO standards.

In response to IPID’s emergency declaration and subsequent discussions, DSO submitted a letter on March 23, 2018 (Ecology 2018), which contained directives regarding further actions IPID needs to take to address the existing conditions at Eightmile Lake. A copy of that letter is included in Appendix A. The letter requests that IPID draw down the lake and maintain the lake at the lowest elevation feasible to provide “some capacity to manage rain and snow runoff,” complete a hydrology and hydraulics analysis of the existing conditions at Eightmile Lake, develop an Emergency Action Plan, come up with a plan to access and monitor conditions at the lake, and describe how weather will be tracked to provide maximum advanced warning in the event of a large storm event.

This report was prepared to address the directive provided by DSO to complete a hydrology and hydraulics analysis of the existing conditions at Eightmile Lake. This directive, as written in DSO’s March 23, 2018 letter (Ecology 2018), is as follows:

Hydrology and Hydraulic Analysis: [IPID] must retain the services of a qualified professional engineering consultant to conduct a detailed analysis


of a dam breach, downstream breach hydraulics, and the design-storm watershed hydrology. The purpose will be to:

Fully characterize and map the breach flood’s downstream inundation, Persons at Risk (PAR) and inundated infrastructure,

Calculate the Design Storm and model the watershed hydrology to produce a hydrograph of the reservoir’s Inflow Design Flood (IDF),

Determine the reservoir’s minimum Design Freeboard, and, Determine if the current combined overflow outlet works are capable

of passing the peak of the IDF, while maintaining the design freeboard.

This analysis must consider the existing, as-is dam geometry (i.e. the full hydraulic height of the embankment: minimum crest to the low-level conduit inlet invert), embankment and foundation materials, and changed conditions on the dam’s watershed as a result of the Jack Creek Wildfire.

1.3 Purpose The purpose of this report is to satisfy the directive from DSO in their March 23, 2018 letter to complete a hydrology and hydraulics analysis of existing conditions at Eightmile Lake. Specifically, the report will follow the hydrologic and hydraulic analyses guidelines listed in Dam Safety Guidelines Part II: Project Planning and Approval of Dam Construction or Modification (Ecology 2008):

Hydrologic/Hydraulic Analyses and Reports (Section 3.3.3 of Dam Safety Guidelines Part II: Project Planning and Approval of Dam Construction or Modification)

‒ Topographic map delineating the watershed boundary and stream network (see Section 2.1 and Figure 2-1)

‒ Description and map delineating land uses, soil types, ground covers, and associated runoff characteristics (see Section 3.2.2)

‒ Listing of all sources of inflow to the reservoir (see Section 3.2.4) ‒ Description of initial watershed conditions and associated assumptions prior to the

occurrence of the inflow design flood (IDF) (see Sections 3.2.2 and 3.2.3) ‒ Unit hydrographs or other similar flood response parameters with calculations or data

supporting the selection of the parameters (see Section 3.1 and Appendices B and C) ‒ Magnitude and temporal distribution of design storm selection for use in computing

the IDF (see Sections 3 and 4) ‒ Listing of input and output of any computer models used (see Appendices D and F)


Dam Failure Analysis (Section 3.3.4 of Dam Safety Guidelines Part II: Project Planning and Approval of Dam Construction or Modification)

‒ Estimation of magnitude of the dam break flood hydrographs resulting from a hypothetical dam failure occurring with the reservoir at normal storage elevation and maximum storage elevation (see Section 5.1)

‒ General description of areas downstream of the dam that could be affected by floodwater from a dam failure (see Section 5.2)

‒ Inundation map delineating maximum areal extent of flooding that could be produced by a dam failure (see Section 5.3)

‒ Downstream hazard classification (see Section 3.1)

This preliminary hydrology and hydraulics report was prepared specifically to address existing conditions at Eightmile Lake. As requested by DSO, the analysis summarized in this preliminary report considers the “existing, as-is dam geometry… embankment and foundation materials, and changed conditions on the dam’s watershed as a result of the Jack Creek Fire.” IPID is proposing to replace the existing dam and low-level outlet facilities at Eightmile Lake with facilities that meet current DSO standards and guidelines. The Eightmile Lake Storage Restoration Feasibility Study (Feasibility Study; Anchor QEA 2018a) provides a description of the preliminary design of those facilities. Additional work is being done to develop the design for those facilities. A separate hydrology and hydraulics report will be prepared and submitted with Dam Construction Permit Application to address the design of those new facilities.


2 Site Description 2.1 Watershed Area As noted earlier, Eightmile Lake is located in the Icicle Creek Subbasin on the east slopes of the Cascade Mountains approximately 10 miles west of the City of Leavenworth, Washington. The lake currently has a full water surface area of approximately 76.6 acres. Eightmile Lake captures water from 3,822-acre drainage basin (approximately 6 square miles), as shown in Figure 2-1, and discharges water to Eightmile Creek, which is a tributary to Icicle Creek. The Eightmile Lake drainage basin is predominantly covered with rocky outcrops and exposed or shallow bedrock, with steep slopes and rugged terrain. Sub-alpine evergreen forest covers approximately 30% of the drainage basin (Anchor QEA 2018a). As noted previously, much of that forest was burned in the Jack Creek Fire during August 2017.

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Figure 2-1Eightmile Lake Drainage Basin

Preliminary Hydrologic and Hydraulic AnalysesEightmile Lake Storage Restoration Project

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EIGHTMILE LAKE DRAINAGE BASINDRAINAGE BASIN AREA: 3,822 ACRES

ESTIMATED AVE. ANNUAL RUNOFF: 19,686 ACRE-FEET

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EIGHTMILE LAKEEXISTING HIGH WATER SURFACE ELEV. = 4,667 FEET


2.2 Existing Reservoir Conditions

2.2.1 Dam and Embankment The existing dam consists of a rock masonry and concrete wall structure with an earthen embankment section. Pieces of the masonry rock and concrete wall structure have deteriorated and fallen off, but most of the structure is still intact. The rock masonry and concrete structure spans approximately 43 feet across the outlet of the lake and features the following:

Flow Control Notch – A 5-foot 9-inch-wide notch near the center of structure, has a crest elevation of 4,661.6 to 4,661.8 feet. Guides were originally included in the notch so that stop logs could be placed to control the level at which the lake spills to the downstream channel through the notch. The stop log guides have deteriorated and no longer function as designed. Prior to the 2017 Jack Creek Fire, IPID placed logs in the notch and draped plastic over the logs to control the high water surface elevation in the lake.

Spillway – The wall south of the notch comprises the historical spillway, with a crest elevation that varies from 4,671.3 to 4,671.4. The spillway crest length is approximately 6 feet. Historically, stop logs were placed in the notch during the spring or early summer to capture runoff and raise the lake level to the spillway elevation (~4,671 feet).

South Wing Wall – A rock masonry wall extends from the spillway to the hillside south of the structure. The high point on the south wing wall is just over 4,673 feet.

North Wing Wall – A rock masonry wall also extends from the notch north of the dam. The highest portion of the north wing wall is also just over 4,673 feet. The earthen embankment portion of the dam was historically connected to the north wing wall and likely matched the elevation at the top of the wing wall.

Stilling Basin and Cutoff Wall – When the gate on the low-level outlet is closed and the lake is full to the top of the stop logs in the flow control notch, water spills over the stop logs into a concrete basin on the downstream side of the structure. It is not clear what the design function of the basin was intended to be, but it appears that it may have originally been the location of the control gate and provided access to the gate. The basin extends down to within a few feet of the top of the low-level outlet pipe, but it is typically filled with rock, logs, and debris. The basin was cleaned out in 2015 by IPID in an attempt to determine the connection between the basin and the low-level outlet pipeline. A concrete cutoff wall forms the downstream edge of the basin and extends down to the low-level outlet pipeline. IPID has observed that water flowing into the basin disappears through the debris into the low-level outlet pipeline. During high flow periods, the basin fills completely with water and excess water discharges over the cutoff wall and to the rock-lined Eightmile Creek channel. The IPID Manager indicated that water typically overtops the cutoff wall on the downstream side of the basin during the spring and early summer.


The earthen embankment section of the dam extends more than 120 feet from the hillside north of the dam to the north wing wall. The portion of the earthen embankment closest to the north wing wall has eroded to an elevation that is more than 4 feet below the crest of the spillway. No historical information has been found to indicate exactly how or when the embankment was eroded. It likely occurred during a large storm event when no one was at the site to observe. The erosion suggests that the spillway is not large enough to accommodate flow rates during peak storm events. The width of the eroded portion of the embankment is approximately 25 feet. The upper (west) portion of the embankment appears to be intact and is covered with large rock.

2.2.2 Low-Level Outlet Pipeline and Gate A slide gate and low-level outlet pipeline control releases from Eightmile Lake to Eightmile Creek. The gate is a 30-inch-diameter, round, cast-iron slide gate and was originally equipped with a hand-wheel operator. The gate is typically submerged in the lake just upstream of the dam but can be opened to release water through the low-level outlet pipeline to Eightmile Creek. The gate has deteriorated and currently must be operated by attaching a log and a come-along to a square metal loop welded to the top of the remaining gate stem below the water surface. This makes gate operation very challenging.

The existing low-level outlet pipeline is nearly 300 feet long and consists of pipe that varies in size and composition. IPID personnel inspected the pipe from the inside late in the summer of 2015 when the lake was drawn down to document the condition and configuration. The following segments of pipe were observed by IPID:

30-inch Corrugated Metal Pipe (CMP), Gate to Dam Structure – This segment of pipe is in relatively good condition and includes two bends.

30-inch Wood Stave Pipe, Under Dam Structure – Under the stilling basin on the downstream side of the dam structure, the pipe transitions to wood stave pipe.

Open Chamber with Log Ceiling – At the cutoff wall on the downstream side of the stilling basin, the pipe transitions into a more open chamber with a log ceiling. The chamber varies in height and width. An opening has eroded at the base of the cutoff wall that allows water in the stilling basin to flow into the chamber from above and down the low-level outlet pipe.

30-inch Log Stave Pipe – A log stave pipe, formed by banding raw, round logs together with steel bands, extends from the open chamber on the downstream side of the first cutoff wall to an open chamber on the upstream side of the second cutoff wall. It appears that concrete may have been formed around the exterior of the logs to form the exterior of the conduit. The log stave pipe has collapsed mid-way between the cutoff walls. IPID has indicated that capacity of the pipeline has declined significantly due to blockage caused by this collapse and is a major concern for IPID.


Open Chamber with Log Ceiling – A second chamber is located at the second cutoff wall, approximately 48 feet downstream of the first cutoff wall.

30-inch CMP, Downstream of Cutoff Wall – A segment of 30-inch CMP extends downstream of the second cutoff wall and includes a bend.

30-inch Wood Stave Pipe – The 30-inch CMP transitions to wood stave pipe again downstream of the bend.

30-inch CMP, Wood Stave Pipe to Outlet – A final segment of 30-inch CMP extends from the wood stave pipe to the outlet to the Eightmile Creek channel. The CMP pipe has a couple of large deformations.

Most of the pipe is buried under large rock. The pipe outlet is typically submerged in the spring and early summer. The IPID Manager indicated that when the gate is open and the reservoir is releasing water, conditions at the pipe outlet are turbulent.

2.2.3 Overflow Channel to Eightmile Creek An overflow or spillway channel extends from the dam above the buried low-level outlet pipeline to the pipe outlet. The channel is filled with large rock. At least some of the rock appears to have been deposited in the channel naturally since it was first constructed. The channel is typically filled with water during the spring and early summer when the lake is spilling. During the late summer, when the gate is open and controlled releases are occurring, the channel runs dry down to the low-level pipeline outlet.

2.2.4 Useable Storage Capacity A survey and lake volume evaluation were completed by Gravity Consulting, LLC, and Forsgren Associates, Inc. (Forsgren 2014), to estimate the volume of the lake at key water surface elevations. The volumes estimated in that report are summarized in Table 2-1. Elevations were surveyed by Gravity Consulting, LLC, relative to the NAVD 88. All elevations reported in this report are based on that datum. Gravity Consulting, LLC, estimated that the current high water surface elevation was approximately 4,667 feet. If IPID attempts to raise the water level higher than that, water overtops the embankment breach around the north wing wall of the dam. The total estimated volume of the lake at that elevation is estimated to be approximately 2,706 acre-feet.


Table 2-1 Lake Volume Summary (From 2014 Forsgren Associates, Inc./Gravity Consulting, LLC Study)

Description

Water Surface

Elevation (Feet)

Water Surface Area

(Acres)

Total Volume

(Acre-feet)

Usable Storage Volume1

(Acre-feet) 1. Existing Low-level Outlet (Max Drawdown) 4,644 44.1 1,331 ↑

1,375 ↓

2. Existing Top of Weir at Flow Control Notch 4,664 73.5 2,486 3. Existing High Water Surface 4,667 76.6 2,706 4. Existing Spillway Crest/Historical High Water

Surface 4,671 80.8 2,998

Note: 1. Icicle and Peshastin Irrigation Districts estimates that additional seepage below the low-level outlet draws the lake down below

elevation 4,644 and that the total useable storage, or total volume that can be released from the lake during the late summer, with the additional seepage that occurs after the lake has been drawn down to the low-level outlet, is approximately 1,600 acre-feet.

Additional topographic survey data was collected as part of the development to of the Feasibility Study (Anchor QEA 2018a) to provide better definition of the embankment, rock masonry/concrete structure, and low-level outlet. Table 2-2 summarizes the key elevations and existing stage-storage-area relationship in the lake, based on a refined analysis with the new data collected. When the original analysis was done by Gravity Consulting, LLC, and Forsgren Associates, Inc., the inlet to the low-level outlet pipeline was submerged and likely buried by rock and debris. The additional survey data gathered in 2016 was collected when the lake was drawn down to the low-level outlet elevation. The surveyed elevation at the invert of the low-level outlet is more than 4 feet higher than what was originally estimated as the maximum drawdown elevation. The lake continues to draw down below the low-level outlet during the late summer due to seepage. For example, the water surface level of the lake during September 2015 was observed at least 3 feet below the low-level outlet invert. So, it is likely that the lake can be drawn down to an elevation beyond the 4,644 feet estimated by Gravity Consulting, LLC, and Forsgren Associates, Inc., through seepage at the end of the summer.


Table 2-2 Lake Volume Summary (Based on Additional Data Collection)

Description

Water Surface

Elevation (Feet)

Water Surface

Area (Acres)

Total Volume (Acre-feet)

Usable Storage Volume2

(Acre-feet) 0. Existing Low Lake Level (Max Drawdown)1, 2 4,644.0± 44.1 1,331

↑ 1,367

↓

1. Existing Low-level Outlet Invert 4,648.7 47.9 1,547 ↑

1,151 ↓

2. Existing Top of Weir at Flow Control Notch 4,664.6 73.7 2,514 3. Existing High Water Surface3 4,667.0± 76.6 2,698 4. Existing Spillway Crest/Historical High Water

Surface 4,671.3 81.7 3,035

Notes: 1. Existing low lake level was not surveyed in fall 2016, but is based on original analysis by Gravity Consulting, LLC, and Forsgren

Associates, Inc. The low lake level has been observed a few feet below the invert of the existing low-level outlet invert. The lake continues to draw down water below the low-level outlet through seepage during the late summer.

2. IPID estimates that additional seepage below the low-level outlet draws the lake down below elevation 4,644 and that the total useable storage, or total volume that can be released from the lake during the late summer, with the additional seepage that occurs after the lake has been drawn down to the low-level outlet, is approximately 1,600 acre-feet.

3. Existing high water surface not surveyed in fall 2016, but is based on original analysis by Gravity Consulting, LLC, and Forsgren Associates, Inc.


3 Hydrologic Analysis 3.1 Design Storm Selection Ecology’s Dam Safety Guidelines Technical Note 3: Design Storm Construction (Technical Note 3; MGS Engineering Consultants, Inc. 2009) provides steps for developing a design storm for use in calculating the IDF hydrograph. Chapter 1.2.2 of Technical Note 3 indicates that the short-duration thunderstorm is commonly the controlling design event in Eastern Washington when the drainage area is less than 50 square miles (MGS Engineering Consultants, Inc. 2009). Short duration storms are high intensity events that typically generate very high peak flood flows. Technical Note 3 also indicates that, in Eastern Washington, the long-duration storm is usually the controlling design event for larger watersheds or when the reservoir storage capacity is large enough to attenuate runoff from the contributing watershed. For this analysis, three design storm types were evaluated: short-duration, intermediate-duration, and long-duration. The following sections detail steps that were followed to complete this evaluation using the Step 8 design storm. This design storm was chosen based on a downstream hazard analysis completed for the Feasibility Study (Anchor QEA 2018a).

3.1.1 Identify Climatic Region The site was determined to be within Climate Region 14 using the map provided in Figure 4 of Technical Note 3. The climate region was verified using the precipitation data lookup worksheets from the DSO website (MGS Engineering Consultants, Inc. 2009). Copies of the precipitation data lookup worksheets are included in Appendix B.

3.1.2 Estimate Mean Annual Precipitation The mean annual, area-weighted precipitation for the Eightmile Lake drainage basin (centroid at 47.518924° N, 120.892544° W) was estimated to be 65.1 inches. The mean annual precipitation was determined using data mapped by MGS Engineering, Inc., and the Spatial Climate Analysis Service at Oregon State University using the PRISM climate model. The mean annual precipitation was verified using the precipitation data lookup worksheets from the DSO website.

3.1.3 Estimate L-Moment Statistics The 2-, 6-, and 24-hour duration L-moment statistics for the project site were estimated based on the location and climatic region using the precipitation lookup worksheet from the DSO website. Statistics are summarized in Table 3-1.


3.1.4 Calculate Mean At-Site Precipitation The 2-, 6-, and 24-hour “at-site” mean precipitation values were calculated using the precipitation lookup worksheets from the DSO website. At-site precipitation values are listed in Table 3-2.

3.1.5 Calculate Base Precipitation Values The short-, intermediate-, and long-duration theoretical maximum precipitation storm values were calculated using the L-moment statistics, at-site mean precipitation, and equations from Technical Note 3, as provided in the precipitation data lookup worksheets from the DSO website. Precipitation values for each storm duration were also calculated for the various return intervals shown in Table 3-1.

Table 3-1 Results of Precipitation Frequency Analysis

Analysis Result Short-Duration (2-hour) Storm

Intermediate-Duration

(6-hour) Storm Long-Duration

(24-hour) Storm L-Cv 0.1414 0.1527 0.1764

L-Skew 0.2074 0.1724 0.1666 At-site Mean Precipitation (inches) 0.726 1.513 3.367

10-year Precipitation (inches) 0.97 2.06 4.79 25-year Precipitation (inches) 1.13 2.39 5.60 100-year Precipitation (inches) 1.39 2.90 6.82

500-year (Step 1) Precipitation (inches) 1.73 3.51 8.23 Step 2 Precipitation (inches) 1.89 3.79 8.84 Step 3 Precipitation (inches) 2.19 4.28 9.87 Step 4 Precipitation (inches) 2.52 4.78 10.90 Step 5 Precipitation (inches) 2.89 5.32 11.95 Step 6 Precipitation (inches) 3.30 5.88 13.01 Step 7 Precipitation (inches) 3.75 6.47 14.07 Step 8 Precipitation (inches) 4.26 7.09 15.15

Notes: 1. For worksheets and additional detail, see Appendix B.


3.1.6 Scaling Precipitation Estimates The precipitation estimates were scaled for design using a design factor recommended by Technical Note 3, as shown in Equation 1:

Equation 1

where: = Scaling precipitation for 2-, 6- or 24-hour index period, in inches = Design Factor; DF = 1.15 for probabilistic uncertainties = Estimated 2-, 6-, or 24-hour precipitation for selected frequency, in inches

3.1.7 Calculate Total Storm Precipitation The total storm precipitation was calculated by multiplying the scaling precipitation by a total storm multiplier based on the climatic region for the project and the hyetograph for that region and storm type, as shown in Equation 2:

Equation 2

where: Total Storm Precip = Total precipitation for the design storm, in inches

= Scaling precipitation for 2-, 6- or 24-hour index period, in inches = Multiplier from mass curve for 4-, 18-, or 72-hour storm

Table 3-2 provides a summary of the design factor, scaling precipitation, multiplier, and total storm precipitation estimated by this method using the precipitation lookup worksheets from the DSO website.


Table 3-2 Total Precipitation for Design Storms

100-year Storms 500-year Storms Step 8 (106-year) Storms

2-hour 6-hour 24-hour 2-hour 6-hour 24-hour 2-hour 6-hour 24-hour Pgds (inches) 1.39 2.90 6.82 1.73 3.51 8.23 4.26 7.09 15.15

DF 1.15 1.15 1.15 1.15 1.15 1.15 1.15 1.15 1.15 Psd (inches) 1.60 3.33 7.84 1.99 4.04 9.46 4.90 8.15 17.42 Multiplier 1.091 1.879 1.685 1.091 1.879 1.685 1.091 1.879 1.685

Total Precipitation for Design Storm

(inches) 1.74 6.26 13.21 2.17 7.59 15.95 5.34 15.31 29.36

3.1.8 Calculate Peak Rainfall Intensity The peak rainfall intensity for the design storms was calculated as shown in Equation 3:

Equation 3

where: Peak Rainfall Intensity = Peak rainfall intensity for the design storm, in inches/hour Total Storm Precip = Total precipitation for the design storm, in inches Peak Intensity Factor = Intensity factor based on climate region and storm type

The peak storm intensities are summarized in Table 3-3.


Table 3-3 Peak Storm Intensities for Design Storms

100-year Storms 500-year Storms Step 8 (106-year) Storms

2-hour 6-hour 24-hour 2-hour 6-hour 24-hour 2-hour 6-hour 24-hour Total

Precipitation for Design

Storm (inches)

1.74 6.26 13.21 2.17 7.59 15.95 5.34 15.31 29.36

Peak Intensity Factor 2.99 0.270 0.123 2.99 0.270 0.123 2.99 0.270 0.123

Peak Storm Intensity

(inches/hour) 4.79 1.69 1.63 5.98 2.05 1.97 14.71 4.14 3.62

3.1.9 Calculate Snowmelt Contribution Floods may be produced during major rainfall events by a combination of rainfall and snowmelt. Rain on snow events typically only occur from late winter to early spring, when only intermediate- and long-duration storms are most likely to occur. The contribution of snowmelt during the intermediate- and long-duration storms was calculated using a snowmelt spreadsheet provided by DSO (Appendix C). The snowmelt contribution was added to the total precipitation value for the design storms as shown in Table 3-4.

Table 3-4 Snowmelt Contribution for Design Storms

Frequency/Design Step Parameter 100-year 500-year Step 8

Intermediate Snowmelt (inches) 1.32 1.42 1.97 Total Precipitation (inches) 6.26 7.59 15.3 Precipitation + Snowmelt (inches) 7.58 9.01 17.3

Long Snowmelt (inches) 4.45 4.65 5.52 Total Precipitation (inches) 13.2 16.0 29.4 Precipitation + Snowmelt (inches) 17.7 20.6 34.9

3.1.10 Calculate Design Storm Hyetograph The design storm hyetographs were calculated based on a dimensionless unit-hyetograph. Technical Note 3 presents unit hyetographs for each storm duration and climatic region. The hyetographs are normalized so that the incremental ordinates add up to 1.0. The ordinates are then simply multiplied


by the total design storm depth to obtain design storm precipitation values. Hyetographs showing the precipitation distribution estimated for the short-, intermediate-, and long-duration Step 8 design storms are plotted in Figure 3-1.

Figure 3-1 Design Storm (Step 8) Hyetographs

3.2 Hydrologic Rainfall Runoff Model

3.2.1 Methodology The U.S. Army Corps of Engineers Hydrologic Modeling System (HEC-HMS; USACE 2017) software was used to estimate runoff volumes and flow rates from the drainage basin tributary to Eightmile Lake for the short-, intermediate-, and long-duration design storms. HEC-HMS software simulates the hydrologic processes of dendritic drainage systems and estimates hydrologic parameters, including infiltration, runoff routing, and runoff hydrographs.

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

0 10 20 30 40 50 60 70 80

PR

EC

IP O

RD

INA

TE

S (

in)

TIME (Hours)

STEP 8 DESIGN STORM-HYETOGRAPH

Short Duration Intermediate Duration Long Duration


The Eightmile Lake drainage basin was further divided into thirteen smaller subbasins for the analysis. These were delineated using GIS software, digital elevation model (DEM) data from the U.S. Geological Survey (USGS), and burn severity maps generated by the U.S. Forest Service Burned Area Emergency Response. The subbasins used for the HEC-HMS analysis are shown in Figure 3-2. The DSO publication Recommended Dam Safety Protocols for Burned Watershed Hydrology Calculations (Ecology 2015), states that if a significant portion of a watershed is outside the fire perimeter, the burned area should be treated as separate subbasins. Subbasins W180, W190, and W290 were each split into two subbasins (a and b) following this guidance to better reflect burned area hydrology.

Figure 3-2 HEC-HMS Subbasin Delineation


3.2.2 Soil Characteristics and Land Cover The National Resources Conservation Service (NRCS) Web Soil Survey (NRCS 2016) for the area was reviewed to identify the soil characteristics for each subbasin. Soils within the drainage area as a whole are characterized as follows:

Rock outcrop – Rubble land-glaciers snowfields complex, 30% to 99% slopes, no hydrologic soil group. This soil covers approximately 51% of the drainage and is described as having lithic bedrock at 0 inch depth.

Andic, Cryumbrepts-Haplocryods – Rock outcrop complex, 30% to 75% slopes, Hydrologic Soil Group C. This soil type covers approximately 29% of the drainage and is categorized as having low available water storage and is underlain by bedrock 20 to 40 inches below ground surface.

Soda – Very boulder sandy loam, 30% to 60% slopes, Hydrologic Soil Group B. This soil group covers approximately 16% of the drainage and is described as well drained, having low available water storage (about 4.3 inches), with a vegetative classification of subalpine fir/Cascade azalea.

Culvop – Very gravelly loam, 30% to 60% slopes, Hydrologic Soil Group D. This soil covers approximately 3% of the drainage and is described as having very low water storage and is underlain by bedrock 10 to 20 inches below ground surface.

Hydrologic Soil Group C was selected for the hydrologic analysis because a majority of the 6.1 square miles of drainage area tributary to Eightmile Lake are classified as rock outcrop complex soil types. Hydrologic Soil Group C type soils have low infiltration rates when thoroughly wetted and consist of soils with a layer that impedes downward movement of water, or soils with moderately fine to fine textures. While the majority of the soils in the drainage have a high rate of water transmission, the underlying bedrock is relatively close to the surface.

3.2.3 Land Cover, Curve Number, and Time of Concentration The drainage area tributary to Eightmile Lake is undeveloped. Vegetation on the lower slopes tributary to the lake consist of shrubs and subalpine fir forests. The NRCS developed a method of combining the effects of soil type, topography, and land cover on the precipitation-runoff relationship into a single parameter called the runoff curve number (CN). The HEC-HMS software uses the NRCS runoff CN as one of the key parameters to calculate runoff. To determine the appropriate runoff CNs for each subbasin, a hydrologic soil group was identified based on the soil characteristics of the site. Pre-fire runoff CNs were estimated from Table 2-2c in the NRCS TR-55 Urban Hydrology for Small Watersheds (NRCS 1986) for each subbasin. Based on review of soil and land cover within the drainage area tributary to the lake, it was determined that site primarily contains a cover type of rocky outcrop and brush with less than 50% ground cover (poor conditions) over soils that are primarily in Hydrologic Soil Group C. Each subbasin was assigned a composite


runoff curve number based on pre-burn conditions that was then modified as directed by Burned Watershed Hydrology Calculations protocols (Ecology 2015). Post-fire CNs are calculated based on burn severity and pre-fire CN values. Short storm CNs were also calculated as the NRCS method underestimates the CN for short storms; these calculations were based on DSO guidance. Basin CNs for pre-fire, post-fire, pre-fire short storms, and post-fire short storms are presented in Table 3-5.

Times of concentration for each subbasin were calculated using guidance from the National Engineering Handbook (NRCS 2010). Parameters used in the calculations were obtained using GIS mapping tools and soil conditions. Times of concentration for each subbasin are presented in Table 3-5.

Table 3-5 Subbasin Times of Concentration and Curve Number Values

Subbasin

Time of concentration

(min) Burn Severity Pre-Fire

CN Post-Fire

CN

Pre-Fire CN (Short storm)

Post-Fire CN (Short storm)

W180A 23.4 None 83 83 90.3 90.3

W180B 5.07 88.6% High 11.4% Low 83 94.2 99 96

W190A 14.8 None 84 84 91.3 91.3

W190B 7.93 95.2% Moderate 4.8% Low 84 90 97.9 90.6

W200 15.0

29.5% High 39.7% Moderate

11.7% Low 19.1% None

78 88.4 96.1 93.9

W250 25.3


3.3% Low 54.7% None

65 77.3 84.1 88.4

W270 12.4


15.7% Low 64.2% None

80 83 90.3 91.2

W290A 17.4 None 84 84 91.3 91.3

W290B 12.8 2.5% High

16.4% Moderate 81.1% Low

84 89.3 97.1 99

W300 18.0


36.1% Low 36.2% None

77 82.5 89.7 91.7


Subbasin

Time of concentration

(min) Burn Severity Pre-Fire

CN Post-Fire

CN

Pre-Fire CN (Short storm)

Post-Fire CN (Short storm)

W310 12.0


15.4% Low 61.5% None

82 84.7 92.1 92.5

W320 13.7


26.2% Low 25.9% None

76 84.6 92 93

W340 12.0


10.7% Low 80.1% None

84 85.2 92.7 93.1

3.2.4 Estimated Inflow from Design Storm The post-burn HEC-HMS model results for peak inflow and runoff volume for the short- (2-hour), intermediate- (6-hour), and long-duration (24-hour) design storms are included in Appendix D. Table 3-6 summarizes the key results.

Table 3-6 Estimated Inflow from Design Storm

Design Storm (Step 8) Peak Inflow and Runoff Volume

Short Intermediate 1 Long 1 Peak Inflow (cfs) 3,840 6,070 5,840 Runoff/Inflow Volume (acre-feet) 1,030 4,660 9,745

Notes: 1. The intermediate- and long-duration storm values include estimated snowmelt contributions.

Design storm hydrographs were generated based on the HEC-HMS model results discussed above. The short-, intermediate-, and long-duration hydrographs for the Step 8 design storm resulting from the HEC-HMS analysis are shown in Figure 3-3.

3.2.5 Comparison to U.S. Geological Survey Methodology The Burned Watershed Hydrology Calculations protocols document (Ecology 2015) suggests that, when used with the short-duration storm, the CN values determined using standard procedures tend to under-estimate the runoff from the short storm. To determine if the short-duration storm might be controlling, a high CN value of 99 was applied to the entire basin tributary to Eightmile Lake. The


short-duration storm was then modeled again in HEC-HMS with the modified CN values. The model results in a peak inflow of 4,560 cubic feet per second (cfs), with an inflow volume of 1,470 acre-feet. While these values are predictably higher than when the original CN values were used, the results imply that the short-duration storm is not the controlling scenario for this basin.

Figure 3-3 Design Storm (Step 8) Inflow Hydrographs

0

1000

2000

3000

4000

5000

6000

7000

0 10 20 30 40 50 60 70 80 90 100

Inflow

(cfs)

Time (Hours)

Short Duration Short Duration (CN=99) Intermediate Long Duration


4 Existing Dam Overflow and Freeboard Analyses 4.1 Existing Reservoir Operation Operation of the existing control facilities at Eightmile Lake is as follows:

Winter – The slide gate on the low-level outlet is closed prior to winter and the stop logs are fully removed from the notch in the dam so that the lake level can rise and spill through the notch during the winter. Typically, the lake is drawn down when the gate is closed. The lake freezes for a portion of the winter, and typically IPID does not access the lake again until late in the spring.

Spring – IPID accesses the lake sometime in the late spring (May or June) after the snow has melted enough to allow access. IPID places stop logs and plastic in the notch to an elevation that is within a foot or so of the top of the eroded embankment (4,667 feet NAVD 88). That allows IPID to capture the late spring and early summer runoff for storage. Under historical operating conditions, stop logs and plastic were placed in the notch up to the historical spillway elevation (4,671 feet NAVD 88).

Summer – Late in the summer, IPID accesses the lake to begin releasing water through the low-level outlet pipeline. The slide gate is open. Typically, the lake is full when releases begin with water spilling over the top of the stop logs in the notch.

Fall – Releases continue from late summer through the end of the irrigation season. IPID typically accesses the lake to prepare it for winter sometime in October. The slide gate is closed, and the stop logs are fully removed from the notch in the dam.

4.2 Current Operating Conditions The lake is currently operating in winter mode. The slide gate was closed last fall, and the stop logs and plastic were removed from the notch in the dam. The lake was fully drawn down to below the low-level outlet. It appears that the gate was not fully closed to a watertight condition due to rocks that may be obstructing the bottom of the gate or due to the difficulty in closing the gate. IPID observed some water flowing in the low-level outlet pipeline on a recent visit to the lake. During IPID’s most recent site visit in early April, the lake was still drawn down to roughly the low-level outlet elevation and was frozen. Several feet of snow were covering the lake.

Due to the emergency conditions at the site due to the Jack Creek Fire, IPID intends to maintain the lake at drawn-down water levels. However, because the gate on the low-level outlet is currently closed, the lake will fill as the snow melts in the watershed through late April and May. If the gate is not fully opened and the low-level outlet pipe unplugged to allow for adequate releases from the lake, the lake will rise to the elevation of the bottom of the notch in the dam and will spill through the notch in the dam by sometime in late May or June. IPID will not be able to open the gate on the low-level outlet until sometime in May after the lake has thawed and may not be able to fully draw


down the lake to the low-level outlet elevation until the low-level outlet pipeline can be unplugged. IPID investigated the feasibility of unplugging the low-level outlet by hand and concluded that safely accessing the low-level outlet pipeline to remove the logs that are plugging it will require an excavator.

4.3 Existing Overflow Analysis The HEC-HMS program was utilized to calculate the impact of flow routing through the existing Eightmile Lake and dam structure under current operating conditions. The existing overflow through the dam consists of an approximately 5-foot 9-inch-wide notch near the center of the structure with a crest elevation of 4,661.6 to 4,661.8 feet.

The Step 8 design storm hydrograph was modeled assuming the initial water level of the lake was equal to the invert of the outlet pipe inlet (4,648.65 feet). As discussed in Section 3.1, this design storm was the design step chosen in the Feasibility Study (Anchor QEA 2018a). The 30-inch outlet pipe was modeled as unplugged and able to flow full. The results presented in Table 4-1 indicate that under these conditions, even with the lake drawn down, the existing overflow would be overtopped during the intermediate- and long-duration design storms.

Table 4-1 Existing Conditions Step 8 Routing – Low-Level Outlet Starting Conditions

Design Storm (Step 8)

Short Intermediate 1 Long 1 Peak Inflow (cfs) 3,840 6,070 5,840 Inflow Volume (acre-feet) 1,030 4,660 9,745 Peak Discharge (cfs) 150 4,680 4,840 Discharge Volume (acre-feet) 80 3,570 8,810 Peak Water Surface Elevation (feet) 4,664.2 4,679.4 4,679.7 Peak Discharge Overtopping (cfs) 0 3,280 3,405


4.4 Freeboard Analysis The existing embankment portion of the dam at Eightmile Lake is eroded to an approximate elevation of 4,667 feet adjacent to the rock-masonry/concrete portion of the dam. As stated in Section 4.1, IPID intends to maintain water levels drawn down to the level of the outlet pipe invert elevation of approximately 4,648 feet, due to the emergency conditions following the 2017 Jack Creek Fire, but will not be able to draw down the water to this elevation until they are able to fully


open the low-level outlet gate and unplug the low-level outlet pipeline. Under conditions with the lake drawn down to the low-level outlet, the freeboard in the lake will be more than 18 feet.

As presented in the previous section, the Step 8 design storm would overtop the current dam and embankment. An analysis was performed to determine the recurrence interval storm event that the dam, under drawn-down conditions with the low-level outlet pipeline wide open, would be able to pass without overtopping. The 10-, 25-, and 100-year recurrence interval long- and intermediate-duration design storms were modeled using HEC-HMS to evaluate the dam’s ability to safely pass the runoff produced from each storm. The results from this analysis are summarized in Table 4-2 and suggest that of the storms simulated, only the intermediate duration, 10-year recurrence interval storm will pass without overtopping the eroded embankment. Any storm larger than that would be expected to overtop the eroded embankment. The freeboard maintained under the intermediate duration, 10-year storm is estimated at 1.3 feet.

Table 4-2 Freeboard Analysis – Low-Level Outlet Starting Conditions

10-year 25-year 100-year Parameter Intermediate Long Intermediate Long Intermediate Long

Peak Inflow (cfs) 1,790 2,380 2,080 2,685 2,510 3,130 Inflow Volume (acre-feet) 1,220 3,750 1,445 4,230 1,775 5,000 Peak Discharge (cfs) 220 1,775 370 2,075 805 2,500 Discharge Volume (acre-feet) 310 2,850 460 3,325 755 4,100 Peak WSE (feet) 4,665.7 4,672.8 4,667.6 4,673.6 4,669.7 4,674.6 Peak Overtopping Flow (cfs) 0 1,040 35 1,275 325 1,585 Freeboard (feet) 1.3 -5.8 -0.6 -6.6 -2.7 -7.6


Additionally, a freeboard analysis was completed assuming that the lake would not be able to be drawn down and the starting condition would be at the bottom of the notch (elevation 4,661.6 feet). The results from this analysis are summarized in Table 4-3 and suggest that none of the intermediate storms simulated would pass without overtopping the eroded embankment. It was determined upon further analysis that any storm larger than a storm that is 80% of the intensity of an intermediate 10-year storm would overtop the existing embankment. For the short-duration storm, it was found that a Step 3 short storm would not overtop the embankment, but higher intensity storms would overtop the embankment if the starting condition is at the bottom of the notch.


Table 4-3 Freeboard Analysis – Flow Control Notch Starting Conditions

Intermediate Short Parameter 10-year 25-year 100-year Step 3 Step 5 Step 8

Peak Inflow (cfs) 1,790 2,080 2,510 1,950 2,870 4,700 Inflow Volume (acre-feet) 1,120 1,445 1,775 518 770 1,270 Peak Discharge (cfs) 960 1,240 1,656 271 547 1,315 Discharge Volume (acre-feet) 977 1,190 1,510 197 338 735 Peak WSE (feet) 4,670.2 4,671.2 4,672.4 4,666.6 4,668.6 4,671.4 Peak Overtopping (cfs) 435 640 950 0 147 696 Freeboard (feet) -3.2 -4.2 -5.4 0.4 -1.6 -4.4



5 Dam Break Analysis A dam break analysis was performed consistent with the DSO requirements and criteria to determine the effects of a possible failure of the existing Eightmile dam on downstream areas. The objective of this analysis was to define the downstream hazard classification, inform the Emergency Action Plan, and identify downstream areas that would be inundated. The dam break was computed using the procedures contained in Dam Safety Guidelines Technical Note 1: Dam Break Inundation Analysis and Downstream Hazard Classification (Ecology 2007).

5.1 Dam Break Geometry The existing dam consists of a rock masonry and concrete wall structure with an earthen embankment section. The rock masonry and concrete structure spans approximately 43 feet across the outlet of the lake. The historical spillway crest elevation varies from 4,671.3 to 4,671.4 feet. There is a 5-foot 9-inch wide notch near the center of the structure with a crest of 4,661.6 to 4,661.8 feet. Guides were originally included in the notch so that stop logs could be placed to control the level at which the lake spills to the downstream channel through the notch. The stop log guides have deteriorated and no longer function as designed, but IPID is still able to place logs and plastic in the notch to raise the water storage level in the lake.

The earthen embankment section of the dam extends more than 120 feet from the hillside north of the dam to the north wing wall of the rock-masonry/concrete structure. The portion of the earthen embankment closest to the north wing wall has eroded to an elevation of approximately 4,667 feet. The width of the eroded portion of the embankment is approximately 25 feet. The upper (west) portion of the embankment appears to be intact and is covered with large rock. The embankment could be classified as erosion resistant for purposes of dam break calculations.

Dam break calculations using the recommended DSO spreadsheet were completed for three scenarios, as follows:

Normal Pool, or Sunny-Day Failure, with Breach to Low-Level Outlet – A piping failure occurring at the low-level outlet was evaluated at a normal pool depth elevation of 4,661.7 feet, equal to the elevation of the bottom of the notch in the dam, and a breach base elevation of 4,648.7 feet.

Maximum Water Surface, or Overtopping Failure with Limited Breach – An overtopping failure occurring at the eroded portion of the embankment was evaluated at a full pool elevation of 4,667 feet, which is equal to the top of the eroded portion of the existing embankment, and a breach base elevation of 4,660 feet.

Maximum Water Surface, or Overtopping Failure with Breach to Low-Level Outlet – An overtopping failure occurring at the eroded portion of the embankment was evaluated at a


full pool elevation of 4,667 feet, which is equal to the top of the eroded portion of the existing embankment, and a breach base elevation of 4,648.7 feet.

Dam break calculations are presented in Appendix E.

The characteristics of a piping breach show a trapezoidal shape with a base width of 67.0 feet, top width of 76.1 feet, 0.25:1 side slopes, break development time of 43 minutes, outflow peak of 7,693 cfs, and a total volume of eroded material of 4,078 cubic yards. Most of the material that would have to be eroded under this scenario is large rock and boulders; therefore, the dimensions of the breach are not likely to be this large.

A breach base elevation of 4,660 feet was selected for the first overtopping failure scenario after reviewing the topography of the area and cross section of the existing dam. This elevation is just below the bottom of the notch in the existing dam. An overtopping event is unlikely to erode material below that elevation to the elevation of the low-level outlet because the low-level outlet extends through approximately 300 feet of very rocky, coarse material. In addition, the eroded embankment appears to have been overtopped many times in recent history and the overtopping does not appear to have caused additional erosion. The overtopping failure had the characteristics of the breach showing a trapezoidal shape with a base width of 105.0 feet, top width of 108.5 feet, 0.25:1 side slopes, break development time of 29 minutes, outflow peak of 5,013 cfs, and a total volume of eroded material of 1,409 cubic yards.

After consultation with DSO, an additional overtopping scenario was evaluated with a breach base elevation equal to the invert of the low-level outlet pipe (4,648.7 feet), consistent with DSO guidelines. This overtopping failure had the characteristics of the breach showing a trapezoidal shape with a base width of 97.6 feet, top width of 106.7 feet, 0.25:1 side slopes, break development time of 48 minutes, outflow peak of 14,907 cfs, and a total volume of eroded material of 5,474 cubic yards.

According to the spreadsheet analysis described above, the worst-case failure conditions would occur during an overtopping failure with the base of the breach located at the invert of the outlet pipe. Note that this peak flow for a dam breach is less than the 100-year peak flow of Icicle Creek (estimated to be approximately 16,800 cfs at the USGS gage). By comparison, the following peak flows have been recorded at the USGS gage on Icicle Creek in the last 40 years:

19,800 cfs on November 29, 1995 15,700 cfs on November 6, 2006 11,000 cfs on November 17, 2015


5.2 Downstream Flood Routing A dam break inundation analysis was conducted using the HEC-RAS one-dimensional model (Version 5.0.3; USACE 2016) consistent with Dam Safety Guidelines. The HEC-RAS model was run in an unsteady state to construct a time history of flooding downstream due to a dam breach.

The model was used to simulate two dam breach scenarios under the following conditions: Full-Pool Failure – The most severe conditions occurred when the dam break was simulated

for an overtopping failure under full-pool conditions. The peak outflow from the dam was estimated to be 14,907 cfs using the peak breach discharge value calculated from the DSO spreadsheet (Appendix E). The dam breach hydrograph from the DSO spreadsheet was input into the HEC-RAS model.

Normal-Pool Failure – A piping failure was simulated at a normal-pool elevation of 4,661.7 feet. The peak outflow from the dam under this scenario is estimated at 7,693 cfs using the peak breach discharge value calculated from the DSO spreadsheet. The dam breach hydrograph was input into the HEC-RAS model.

Reservoir Inflow – For the overtopping (full-pool) failure, the breach flow was added to a base inflow value of 322 cfs, the estimated flow into Eightmile Lake during high-flow conditions in June. The base flow value was estimated by comparing the 10-year storm flow at Eightmile Lake with the 10-year recurrence interval flow at the Icicle Creek gage. This ratio was multiplied by the 10% exceedance flows for June at the Icicle Creek gage to get the estimated inflows at Eightmile Lake. For the normal-pool failure, the breach flow was added to a base inflow value of 200 cfs, the estimated typical flow conditions in June. Similarly, this base flow value was estimated by comparing the 10-year storm flow at Eightmile Lake with the 10-year recurrence interval flow at the Icicle Creek gage. This ratio was multiplied by the mean flows for June at the Icicle Creek gage to get the estimated inflows at Eightmile Lake.

Downstream Flows – Icicle Creek and Wenatchee River flows for the overtopping breach conditions were estimated using 10% exceedance flows for June from the active USGS gages. These flows were 2,887 cfs and 13,041 cfs, respectively. For the normal-pool breach conditions, Icicle Creek and Wenatchee River flows were estimated using mean flows for June from the USGS gages. These flows were 1,900 cfs and 8,470 cfs, respectively.

Downstream Boundary Conditions – The downstream boundary condition was set as the rating curve for the Wenatchee River at Peshastin USGS gage (#12459000).

Topography – Light Detection and Ranging (LiDAR) data collected in 2015 were used where available, including the Wenatchee River from the Peshastin gage to the Icicle River confluence, and the Icicle River from its confluence with the Wenatchee River to river mile (RM) 7.1. USGS DEM data were used in other areas.

Manning’s Roughness ‘n’ Values – Manning’s roughness ‘n’ values were assumed to be 0.06 in the channel and 0.10 in the overbanks.


To simplify the HEC-RAS model, it was assumed, given the steep and confined geometry of Eightmile Creek, that the peak discharge from the dam breach would not significantly attenuate in Eightmile Creek. Consequently, the breach flow and Eightmile Creek base inflow were modeled as inflow directly to Icicle Creek at its confluence with Eightmile Creek. The model was used to analyze the reach of Icicle Creek from its confluence with Eightmile Creek to its confluence with the Wenatchee River, and the reach of the Wenatchee River from the Icicle Creek confluence to RM 21.5. HEC-RAS model results for the dam breach analysis are included in Appendix F.

5.3 Inundation Mapping Inundation maps were prepared to show the extent of flooding that is predicted to occur in the event of a sudden and complete dam breach and are presented in Figures 5-1 to 5-10. Tables 5-1 and 5-2 summarize flood depths and widths for various locations downstream Eightmile Lake for the overtopping and normal-pool dam break conditions.


Table 5-1 Approximate Maximum Water Depths and Widths for Overtopping Dam Breach Downstream of Eightmile Lake

Location Stream

Model Cross-Section

Figure Label

Approximate Maximum

Water Depth (foot)

Approximate Maximum

Water Width (foot)

Time to Maximum Conditions

of Dam Breach (hours)

Eightmile Creek and Icicle Creek Confluence Icicle Creek 50122.4 XS-15 8.9 155 0.5

Immediately Downstream from LiDAR/DEM

Transition Icicle Creek 45115.09 XS-14 8.9 130 0.6

Unnamed Bridge Icicle Creek 40830.82 XS-13 13.2 200 0.7 Snow Creek Confluence Icicle Creek 31421.65 XS-12 9.6 130 0.8 Immediately Upstream

from Icicle Island Icicle Creek 30588.39 XS-11 8.3 195 0.8

Sleeping Lady Resort Icicle Creek 25032.33 XS-10 9.7 250 0.8 Immediately Upstream from Hatchery Channel

Inlet Icicle Creek 22829.34 XS-9 13.8 250 0.9

Downstream End of Hatchery Channel

Hatchery Channel 354.6978 XS-8 5.9 180 1.1

Icicle Creek Historic Channel Icicle Creek 17441.21 XS-8 10.9 900 1.3

Upstream from Leavenworth Road Bridge Icicle Creek 14297.71 XS-7 15.2 2,300 1.5

Near the End of Shore Street Icicle Creek 6178.466 XS-6 10.8 1,500 2.1

Near End of Wilson Street Icicle Creek 3426.354 XS-5 10.0 1,950 2.6 Upstream from

Wenatchee River Confluence

Icicle Creek 936.7949 XS-4 10.2 850 2.8

Leavenworth Golf Club Wenatchee River 255 XS-3 11.7 1,120 2.9

Immediately Upstream from U.S. Highway 2

Wenatchee River 146 XS-2 12.9 150 3.1

USGS Gage 12459000 Wenatchee River 0 XS-1 10.5 260 3.3


Table 5-2 Approximate Maximum Water Depths and Widths for Normal-Pool Dam Breach Downstream of Eightmile Lake

Location Stream

Model Cross-Section

Figure Label

Approximate Maximum

Water Depth (foot)

Approximate Maximum

Water Width (foot)

Time to Maximum Conditions

of Dam Breach (hours)

Eightmile Creek and Icicle Creek Confluence Icicle Creek 50122.4 XS-15 6.7 145 0.5

Immediately Downstream from LiDAR/DEM

Transition Icicle Creek 45115.09 XS-14 6.6 115 0.7

Unnamed Bridge Icicle Creek 40830.82 XS-13 10.3 95 0.7 Snow Creek Confluence Icicle Creek 31421.65 XS-12 7.4 130 0.8 Immediately Upstream

from Icicle Island Icicle Creek 30588.39 XS-11 6.3 175 0.8

Sleeping Lady Resort Icicle Creek 25032.33 XS-10 7.6 180 0.9 Immediately Upstream from Hatchery Channel

Inlet Icicle Creek 22829.34 XS-9 11.4 230 0.9

Downstream End of Hatchery Channel

Hatchery Channel 354.6978 XS-8 4.5 110 1.3

Icicle Creek Historic Channel Icicle Creek 17441.21 XS-8 9.0 820 1.5

Upstream from Leavenworth Road Bridge Icicle Creek 14297.71 XS-7 13.0 600 1.7

Near the End of Shore Street Icicle Creek 6178.466 XS-6 9.8 600 2.3

Near End of Wilson Street Icicle Creek 3426.354 XS-5 9.0 2,240 2.8 Upstream from

Wenatchee River Confluence

Icicle Creek 936.7949 XS-4 8.8 350 3.1

Leavenworth Golf Club Wenatchee River 255 XS-3 10.5 1,075 3.2

Immediately Upstream from U.S. Highway 2

Wenatchee River 146 XS-2 11.6 150 3.3

USGS Gage 12459000 Wenatchee River 0 XS-1 9.0 260 3.7


Based on these analyses, the flood wave would reach the confluence of Eightmile Creek and Icicle Creek in 0.5 hours and the confluence of Icicle Creek and the Wenatchee River in 2.8 hours. Impacted residences are mapped in Figures 5-1 to 5-10. A total of 40 residences are mapped and include residences in the Icicle Island area downstream of the Snow Creek confluence with Icicle Creek and areas near the Leavenworth National Fish Hatchery. Other structures, such as barns or outbuildings, were not identified on the inundations maps; however, these structures could also be damaged as a result of a breach. Several roads and bridge crossings have the potential to be overtopped or damaged by the flood wave including Forest Roads NF-7601 and NF-112, a bridge over Icicle Creek at RM 7, two bridge crossings near Icicle Island, a bridge crossing near the downstream end of the Leavenworth National Fish Hatchery channel, and the bridge at East Leavenworth Road. Other infrastructure that may also be damaged by the flood wave include the IPID intake facilities and access bridge, the USGS streamflow gage on Icicle Creek (12458000), the foot bridge at the Snow Creek trailhead, the Leavenworth National Fish Hatchery intake facility it shares with the Cascade Orchards Irrigation Company, and the Eightmile Lake trailhead.

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Publish Date: 2018/05/18, 12:25 PM | User: jsextonFilepath: J:\Projects\Icicle and Peshastin Irrigation Districts\Eightmile Lake Storage Restoration\GIS\EightmileInundationFigure_5-1.mxd

Figure 5-1Inundation Area


LEGEND!( Residences Impacted by Overtopping Breach& Residences Impacted by Normal Pool and Overtopping Breach

Inundation Area - Normal Pool Breach

Inundation Area - Overtopping BreachMajor Roads

E River Mile

Leavenworth City Limits

Figure ExtentsStreams40-ft Contours200-ft Contours

1. Flood inundation area for normal-pool breach based on a "sunny day" breach scenario with apool elevation of 4,661.7 ft. and a breach base elevation of 4648.7 ft. Results represent breachflows added to mean June flow condition for Icicle Creek and Wenatchee River.2. Flood inundation area for overtopping breach based on a "full-pool" breach scenario, with apool elevation of 4,667 ft. and a breach base elevation of 4648.7 ft. Assumed 10% exceedanceflows (high flow) in June for Icicle Creek and Wenatchee River flow conditions and inflow toEightmile Lake.3. Topographic data: LiDAR data, where available, and USGS DEM data where LiDAR data was notavailable.

E

E

XS-15Overtopping Breach Conditions:Peak WSE = 1,919.9 FeetPeak Q = 17,700 cfsTime to Peak = 0.5 Hours

June High Flow Conditions:Peak WSE = 1,915.1 FeetPeak Q = 3,210 cfs



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1. Flood inundation area for normal-pool breach based on a "sunny day" breach scenario with apool elevation of 4,661.7 ft. and a breach base elevation of 4648.7 ft. Results represent breachflows added to mean June flow condition for Icicle Creek and Wenatchee River.2. Flood inundation area for overtopping breach based on a "full-pool" breach scenario, with apool elevation of 4,667 ft. and a breach base elevation of 4648.7 ft. Assumed 10% exceedanceflows (high flow) in June for Icicle Creek and Wenatchee River flow conditions and inflow toEightmile Lake.3. Topographic data: LiDAR data, where available, and USGS DEM data where LiDAR data was notavailable.

Publish Date: 2018/05/18, 1:55 PM | User: jsextonFilepath: J:\Projects\Icicle and Peshastin Irrigation Districts\Eightmile Lake Storage Restoration\GIS\EightmileInundationFigures_L.mxd

LEGEND! Residences Impacted by Overtopping Breach! Residences Impacted by Normal Pool and Overtopping Breach

Inundation Area - Normal Pool BreachInundation Area - Overtopping BreachMajor Roads

E River Mile

Cross-Sections

Leavenworth City LimitsStreams40-ft Contours200-ft Contours



ABBREVIATIONS:

WSEL = Water Surface ElevationQ = FlowCFS = Cubic Feet per SecondUSGS = United States Geological SurveyDEM = Digital Elevation ModelLiDAR = Light Detection and Ranging

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NOTES:1. Flood inundation area for normal-pool breach based on a "sunny day" breach scenario with apool elevation of 4,661.7 ft. and a breach base elevation of 4648.7 ft. Results represent breachflows added to mean June flow condition for Icicle Creek and Wenatchee River.2. Flood inundation area for overtopping breach based on a "full-pool" breach scenario, with apool elevation of 4,667 ft. and a breach base elevation of 4648.7 ft. Assumed 10% exceedanceflows (high flow) in June for Icicle Creek and Wenatchee River flow conditions and inflow toEightmile Lake.3. Topographic data: LiDAR data, where available, and USGS DEM data where LiDAR data was notavailable.




E River Mile

Cross-SectionsLeavenworth City LimitsStreams40-ft Contours200-ft Contours



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Icicle CreekOvertopping Breach Conditions:Peak WSE = 1,129.9 FeetPeak Q = 8,410 cfsTime to Peak = 1.3 Hours




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NOTES:1. Flood inundation area for normal-pool breach based on a "sunny day"breach scenario with a pool elevation of 4,661.7 ft. and a breach baseelevation of 4648.7 ft. Results represent breach flows added to mean Juneflow condition for Icicle Creek and Wenatchee River.2. Flood inundation area for overtopping breach based on a "full-pool"breach scenario, with a pool elevation of 4,667 ft. and a breach baseelevation of 4648.7 ft. Assumed 10% exceedance flows (high flow) in Junefor Icicle Creek and Wenatchee River flow conditions and inflow toEightmile Lake.3. Topographic data: LiDAR data, where available, and USGS DEM data

LEGEND:! Residences Impacted by Overtopping Breach! Residences Impacted by Normal Pool and Overtopping Breach


E River Mile


Publish Date: 2018/05/18, 1:50 PM | User: jsextonFilepath: J:\Projects\Icicle and Peshastin Irrigation Districts\Eightmile Lake Storage Restoration\GIS\EightmileInundationFigures_P.mxd



ABBREVIATIONS:WSEL = Water Surface ElevationQ = FlowCFS = Cubic Feet per Second

USGS = United States Geological SurveyDEM = Digital Elevation ModelLiDAR = Light Detection and Ranging

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6 Summary and Next Steps Hydrologic and hydraulic analyses were completed for the existing Eightmile Lake Dam as part of the directives set forth by DSO in response to an emergency declaration by IPID. Specifically, the following requests were addressed:

Fully characterize and map the breach flood’s downstream inundation, PARs, and inundated infrastructure.

‒ Dam breach analyses were developed for the existing dam assuming the breach would be caused by either a piping failure or an overtopping failure. Using the DSO dam breach spreadsheet analysis, the worst-case failure would occur during an overtopping failure, which would have a breach development time of 48 minutes and a peak outflow of 14,907 cfs. A downstream inundation analysis was developed using an unsteady, one-dimensional HEC-RAS model for the dam breach conditions. The peak flood wave takes approximately 0.5 hours from the breach to travel to the confluence of Eightmile Creek and Icicle Creek, and approximately 2.8 hours to travel to the confluence of Icicle Creek and the Wenatchee River. Impacted infrastructure and PARs were identified, including 40 residences, most of which are located on Icicle Island and near the Leavenworth National Fish Hatchery.

Calculate the design storm and model the watershed hydrology to produce a hydrograph of the reservoir’s IDF.

‒ Hyetographs were developed for Eightmile Lake Dam storms based on mean annual precipitation, location, and snowmelt. These hyetographs were used as input into a HEC-HMS model of Eightmile Lake. The HEC-HMS model was previously developed for the Feasibility Study and was updated with revised subbasin conditions due to the Jack Creek Fire. Peak inflows from the Step 8 design storm were estimated to be 3,840 cfs for the short-duration storm and 6,070 cfs for the intermediate-duration storm.

Determine the reservoir’s minimum design freeboard. ‒ The HEC-HMS model was used to analyze the existing dam to estimate the storm

events where the existing embankment would be overtopped. The analyses were completed assuming the starting pool elevation was at the low-level outlet and then at the bottom of the flow control notch. For the short-duration storm events, the low-level outlet starting condition could pass the Step 8 short-duration storm without overtopping the embankment, while the flow control notch starting condition would overtop the embankment above a Step 3 short-duration storm. For the intermediate-duration storm events, the low-level outlet starting condition would overtop the embankment at a 25-year intermediate-duration storm event, while the flow control notch starting condition would overtop the embankment at 80% intensity of a 10-year intermediate-duration storm event.


Determine if the current combined overflow outlet works are capable of passing the peak of the IDF, while maintaining the design freeboard.

‒ As noted in the previous bullet, overtopping the embankment would occur in 25-year intermediate-duration storms and greater, so the design freeboard for the current dam would not be maintained.

The following are recommended for next steps: Update the emergency action plan for the existing reservoir using the inundation area

developed from the dam breach analysis. Implement the three-step Eightmile Lake Interim Action Plan (Anchor QEA 2018b), which

includes the following: ‒ Step 1: Modify and stabilize the existing embankment by regrading and hardening the

embankment crest to allow the lake to safely spill over the embankment without causing further erosion or failure.

‒ Step 2: Install a temporary siphon to allow for initial drawdown of the lake to below the notch in the existing rock-masonry/concrete dam structure, close the low-level outlet pipe completely, and remove obstructions in the low-level outlet pipe.

‒ Step 3: Adjust the temporary siphon by burying the siphon in the top of the embankment to allow for further drawdown and improved control of lake levels. This final adjustment will allow the lake to automatically draw down to below the low-level outlet to provide a cushion for high runoff events.

Continue to refine the design of permanent improvements to the dam and low-level outlet at Eightmile Lake.

Develop revised hydrologic and hydraulic analyses for proposed design improvements to the dam.


7 References Anchor QEA (Anchor QEA, LLC), 2018a. Eightmile Lake Storage Restoration Feasibility Study. Prepared

with Aspect Consulting, LLC. Prepared for Icicle and Peshastin Irrigation Districts and Chelan County Natural Resources Department. Icicle Creek Water Resource Management Strategy, April 2018.

Anchor QEA 2018b. Memorandum to: Tony Jantzer, Joe Witczak, Guy Hoyle-Dodson, Gus Ordonez, and Rene Renteria. Regarding: Eightmile Lake Interim Action Plan. May 11, 2018.

Ecology (Washington State Department of Ecology), 2007. Dam Safety Guidelines Technical Note 1: Dam Break Inundation Analysis and Downstream Hazard Classification. Publication No. 92-55e. July 1992, Revised December 2007.

Ecology, 2008. Dam Safety Guidelines Part II: Project Planning and Approval of Dam Construction or Modification. 92-55B. July 1992 (Revised February 2008).

Ecology, 2015. Recommended dam safety protocols for burned watershed hydrology calculations. Publication No. 15-11-013. Revised August 2015.

Ecology, 2018. Re: Eightmile Lake Dam DSO File: No. CH45-0228. Letter to Anthony D. Jantzer, Icicle & Peshastin Irrigation District. March 23, 2018.

Forsgren (Forsgren Associates, Inc.), 2014. Draft Icicle Irrigation District Instream Flow Improvement Options Analysis Study. Prepared for Trout Unlimited with input from Gravity Consulting. July 22, 2014.

MGS Engineering Consultants, Inc., 2009. Dam Safety Guidelines Technical Note 3: Design Storm Construction. Prepared for Water Resources Program, Dam Safety Office. October 2009 (Revised).

NRCS (United States Department of Agriculture National Resources Conservation Service), 1986. Urban Hydrology for Small Watersheds. 210-VI-TR-55. June 1986.

NRCS, 2010. National Engineering Handbook. Part 630 – Hydrology. 210-VI-NEH, May 2010.

NRCS, 2016. Web Soil Survey. Updated: August 10, 2016. Cited: February 2017. Available from: https://websoilsurvey.sc.egov.usda.gov/App/HomePage.htm.

USACE, 2017. Hydrologic Engineering Center Hydrologic Modeling System (HEC-HMS). Version 4.2.1. March 2017.

Appendix A Ecology Dam Safety Office March 23, 2018 Letter

Appendix B Precipitation Data Worksheets

Precipitation Magnitude-Frequency Gridded Data Set Lookup Calculator

This Work Book contains a Visual Basic for Applications macro that interpolates precipitation magnitude fromgridded data set files. The user inputs the latitude and longitude of the location of interest, the precipitation duration (2-hours, 6-hours, or 24-hours), and the interpolation method. Clicking the Calculate button runs the macro and outputs the Climatic Region Number, L-Moment Statistics, and Precipitation Magnitude-Frequency Statistics below.

User Inputs Project Name Eightmile LakeLatitude (Decimal Degrees) 47.5199Longitude (Decimal Degrees) 120.87919Duration (hours) 2 (Enter 2, 6, or 24)Grid Cell Interpolation Method 1 (Enter 0 for Center of Grid-Cell or 1 for Inverse Distance Weighting)

Program OutputClimatic Region Number 14Mean Annual Precipitation (inches) 65.1At-Site Mean (inches) 0.726L-Cv 0.1414L-Skew 0.2074Hondo -0.150

Precipitation Magnitude Frequency Output, 2-Hour DurationPrecipitation Frequency

10-Year 0.9725-Year 1.13

100-Year 1.39Step 1 1.73Step 2 1.89Step 3 2.19Step 4 2.52Step 5 2.89Step 6 3.30Step 7 3.75Step 8 4.26

Program Status Message Successful

7326 Boston Harbor Road NE Olympia, WA 98506 (360) 570-3450 www.mgsengr.com

Calculate

Eightmile Lake (Icicle and Peshastin Irrigation Districts)

Worksheet for Computation of Short Duration Precipitation Magnitude-Frequency Curve Reference: Technical Note 3, Oct 2009 revision

JTS, 12/09/2016 page 1 of 2

Project data: Input InputDam location: T 24 N, R 16E, Section 33; 10 miles W of Levenworth, WAWatershed Lat/Long: 47.5199 deg. N -120.8792 deg. W (> 3 decimal places)Watershed elevation: 6026 feet (Lat/Long and elev for centroid of watershed)Climatic Region: 14 (MGS Look-up Calculator)Mean Annual Precip: 65.1 inches (MGS Look-up Calculator)Duration of interest: 2 hours (Index for short duration storm)Design Step: 8 (Worksheet from Tech Note 2)Drainage area: 6 sq.miles. (Compare to small watershed < 1 sq.mile.)

Input

Key equations :Precipitation estimates are calculated from gridded data set files by the MGS Look-up Calculator (the "Calculator" tab in this workbook) using the four-parameter Kappa probablility distribution. The specific equations are described in more detail in the following references :

Schaefer MG, Barker BL, Taylor GH and Wallis JR, Regional Precipitation-Frequency Analysis and Spatial Mapping of Precipitation for 24-Hour and 2-Hour Durations in Western Washington, prepared for Washington State Department of Transportation, Report WA-RD 544.1, MGS Engineering Consultants, March 2002.

Schaefer MG, Barker BL, Taylor GH and Wallis JR, Regional Precipitation-Frequency Analysis and Spatial Mapping of Precipitation for 24-Hour and 2-Hour Durations in Eastern Washington, prepared for Washington State Department of Transportation, MGS Engineering Consultants, January 2006.

The calculations were extended to the Dam Safety storms by the update to Technical Note 3. The gridded data sets are provided by Ecology along with this spreadsheet and look-up calculator.

Scaling precipitation, Psd = DF * Pgds Use design factor = 1.15 Inputwhere: Pgds = estimated 2-hr precip for selected frequency, inches

DF = design factor; DF = 1.15 for new damsPsd = scaling precip for 2-hr index period, inches

Total storm precip = (scaling precip for 2-hr index) x (multiplier from mass curve for 4-hr storm)multiplier for 4-hr storm = 1.0910 for Climatic Region 14

(from Multipliers worksheet) Hyetograph no. 6

This project :

Frequency / design step : 10 yr 25 yr 100 yr Step 1 Step 2 Step 3Precip estimate, Pgds (in.) : 0.97 1.13 1.39 1.73 1.89 2.19Scaling precipitation, Psd (in.) : 1.11 1.30 1.59 1.99 2.18 2.52Total precip for design storm : 1.22 1.41 1.74 2.17 2.38 2.75

Frequency / design step : Step 4 Step 5 Step 6 Step 7 Step 8 PMPPrecip estimate, Pgds (in.) : 2.52 2.89 3.30 3.75 4.26 7.26Scaling precipitation, Psd (in.) : 2.90 3.32 3.79 4.32 4.90 7.26Total precip for design storm : 3.16 3.63 4.14 4.71 5.34 7.92


Worksheet for Computation of Short Duration Precipitation Magnitude-Frequency Curve Reference: Technical Note 3, Oct 2009 revision

JTS, 12/09/2016 page 2 of 2

Comparison to PMP for local storm (thunderstorm). Ref: HMR-57, Fig. 11.19 and 11.12, Table 11.4.Input

Local storm, 1-hour PMP = 6.6 in.2-hour PMP = 110% x 1-hr = 7.3 in.

Frequency / design step : Step 3 Step 4 Step 5 Step 6 Step 7 Step 8Scaling precipitation, Psd (in.) : 2.52 2.90 3.32 3.79 4.32 4.90Percentage of 2-hr PMP (%) : 34.7 39.9 45.8 52.3 59.4 67.5

Note: Per Tech Note 3, page 10: For IDF = PMF, use PMP > Step 6.

Basin average precipitation for large watershed.

Drainage area = 6 sq.miles. (Compare to small watershed < 1 sq.mile.)

Basin avg. precip = 92 % of total storm point precip.(from Multipliers worksheet)

Frequency / design step : 10 yr 25 yr 100 yr Step 1 Step 2 Step 3Total storm point precip : 1.22 1.41 1.74 2.17 2.38 2.75Basin avg total storm precip : 1.12 1.30 1.60 2.00 2.19 2.53

Frequency / design step : Step 4 Step 5 Step 6 Step 7 Step 8 PMPTotal storm point precip : 3.16 3.63 4.14 4.71 5.34 7.92Basin avg total storm precip : 2.91 3.34 3.81 4.33 4.92 7.29

Peak rainfall intensity for design storm.

Peak rainfall intensity (in/hr) = (total storm precip) x (peak intensity factor)peak intensity factor = 2.99172 for Climatic Region 14(from Multipliers worksheet) Hyetograph no. 6

Frequency / design step : 10 yr 25 yr 100 yr Step 1 Step 2 Step 3Basin avg total storm precip : 1.12 1.30 1.60 2.00 2.19 2.53Peak storm intensity (in/hr) : 3.34 3.89 4.79 5.98 6.54 7.57

Frequency / design step : Step 4 Step 5 Step 6 Step 7 Step 8 PMPBasin avg total storm precip : 2.91 3.34 3.81 4.33 4.92 7.29Peak storm intensity (in/hr) : 8.71 9.98 11.39 12.96 14.71 21.80

Total storm multipliers for short duration storm hyetographs MDW, 10/13/09 page 1 of 1

Total storm Peak intensityRegions Hyetograph multiplier factor

5 5 1.2050 2.23068151-142 5 1.2050 2.2306815-154 5 1.2050 2.2306831-32 5 1.2050 2.23068

14-147-13 6 1.0910 2.9917277-07 7 1.0350 3.50136

This project :

Region Hyetograph Multiplier Factor

14 6 1.0910 2.99172Input Input Input

Areal adjustment factors for short duration storm hyetographs MDW, 9/11/09

Refs : Basin average precipitation for large watershed. Tech Note 3 (2009 update), Table 1 on page 9

Schaefer, Extreme Storms; Figure 16 on page 70Drainage area Percentage of

(sq.miles) point precip (%)< 1 100

1 < 2 1002 < 3 993 < 5 965 < 7 92

7 < 10 89> 10 85

This project : Drainage area = 6 sq.miles. (Compare to small watershed < 1 sq.mile.)

Basin avg. precip = 92 % of total storm point precip.Input






10-Year 2.0625-Year 2.39




Calculate


Worksheet for Computation of Intermediate Precipitation Magnitude-Frequency Curve Reference: Technical Note 3, Oct 2009 revision

JTS, 12/09/2016 page 1 of 3

Project data: Input InputDam location: T 24 N, R 16E, Section 33; 10 miles W of Levenworth, WAWatershed Lat/Long: 47.5199 deg. N -120.8792 deg. W (> 3 decimal places)Watershed elevation: 6026 feet (Lat/Long and elev for centroid of watershed)Climatic Region: 14 (MGS Look-up Calculator)Mean Annual Precip: 65.1 inches (MGS Look-up Calculator)Duration of interest: 6 hours (Index for intermediate storm)Design Step: 8 (Worksheet from Tech Note 2)Drainage area: 6 sq.miles. (Compare to small watershed < 10 sq.miles)

Input

Key equations : Precipitation estimates are calculated from gridded data set files by the MGS Look-up Calculator (the "Calculator" tab in this workbook) using the four-parameter Kappa probablility distribution. The specific equations are described in more detail in the following references :








This project :





JTS, 12/09/2016 page 2 of 3

Comparison to PMP for general storm. Ref: HMR-57, Map 1 - NW, Table 10.10.

PMP for a 6-hour period is estimated as a percentage of the 24-hour PMP. The percentage factor varies by climatic region as follows :

Western Washington Eastern WashingtonCoast Olympics Cascades Puget Sound Mountains Central Basin

Regions : 5 151-142 15-154 31-32 14-147-13 77-07Factor : 0.43 0.40 0.40 0.44 0.52 0.59

This project : InputGeneral storm, 24-hour PMP = 18.5 in. From HMR-57 Map 1

For region: 146-hr PMP= 0.52 x 24-hr = 9.62 in.

InputFrequency / design step : Step 3 Step 4 Step 5 Step 6 Step 7 Step 8Scaling precipitation, Psd (in.) : 4.92 5.50 6.12 6.76 7.44 8.15Percentage of 6-hr PMP (%) : 51.1 57.2 63.6 70.3 77.3 84.7


Comparison to PMP for local storm (thunderstorm). Ref: HMR-57, Fig. 11.19 and 11.12, Table 11.4.Input

Local storm, 1-hour PMP = 6.6 in.6-hour PMP = 115% x 1-hr = 7.6 in.

Frequency / design step : Step 3 Step 4 Step 5 Step 6 Step 7 Step 8Scaling precipitation, Psd (in.) : 4.92 5.50 6.12 6.76 7.44 8.15Percentage of 6-hr PMP (%) : 64.8 72.5 80.6 89.1 98.0 107.4




JTS, 12/09/2016 page 3 of 3



Frequency / design step : 10 yr 25 yr 100 yr Step 1 Step 2 Step 3Total precip for design storm : 4.46 5.16 6.26 7.59 8.20 9.24Peak storm intensity (in/hr) : 1.21 1.40 1.69 2.05 2.22 2.50

Frequency / design step : Step 4 Step 5 Step 6 Step 7 Step 8 PMPTotal precip for design storm : 10.33 11.49 12.70 13.97 15.31 18.08Peak storm intensity (in/hr) : 2.79 3.11 3.43 3.78 4.14 4.89

Total storm multipliers for intermediate storm hyetographs

MDW, 10/13/09 page 1 of 1


5 8 1.6810 0.31408151-142 9 1.8580 0.2841615-154 9 1.8580 0.2841631-32 10 1.6670 0.33352

14 11 1.8790 0.27032147-77-07 12 1.5515 0.40476

13 13 1.6285 0.35612

This project :








10-Year 4.7925-Year 5.60




Calculate


Worksheet for Computation of Long Duration Precipitation Magnitude-Frequency Curve Reference: Technical Note 3, Oct 2009 revision

JTS, 12/09/2016 page 1 of 2

Project data : Input InputDam location: T 24 N, R 16E, Section 33; 10 miles W of Levenworth, WAWatershed Lat/Long: 47.5199 deg. N -120.8792 deg. W (> 3 decimal places)Watershed elevation: 6026 feet (Lat/Long and elev for centroid of watershed)Climatic Region: 14 (MGS Look-up Calculator)Mean Annual Precip: 65.1 inches (MGS Look-up Calculator)Duration of interest: 24 hours (Index for long duration storm)Design Step: 8 (Worksheet from Tech Note 2)Drainage area: 6 sq.miles. (Compare to small watershed < 10 sq.miles)

Input

Key equations : Precipitation estimates are calculated from gridded data set files by the MGS Look-up Calculator (the "Calculator" tab in this workbook) using the four-parameter Kappa probablility distribution. The specific equations are described in more detail in the following references :








This project :




Worksheet for Computation of Long Duration Precipitation Magnitude-Frequency Curve Reference: Technical Note 3, Oct 2009 revision

JTS, 12/09/2016 page 2 of 2

Comparison to PMP for general storm. Ref: HMR-57, Map 1 - NW.Input

General storm, 24-hour PMP = 18.5 in.

Frequency / design step : Step 3 Step 4 Step 5 Step 6 Step 7 Step 8Scaling precipitation, Psd (in.) : 11.35 12.54 13.74 14.96 16.18 17.42Percentage of 24-hr PMP (%): 61.3 67.8 74.3 80.8 87.5 94.2




Frequency / design step : 10 yr 25 yr 100 yr Step 1 Step 2 Step 3Total precip for design storm : 9.29 10.86 13.21 15.95 17.14 19.12Peak storm intensity (in/hr) : 1.15 1.34 1.63 1.97 2.11 2.36

Frequency / design step : Step 4 Step 5 Step 6 Step 7 Step 8 PMPTotal precip for design storm : 21.13 23.16 25.21 27.27 29.36 31.18Peak storm intensity (in/hr) : 2.61 2.86 3.11 3.37 3.62 3.85

Total storm multipliers for long duration storm hyetographs

MDW, 10/13/09 page 1 of 1


5 14 1.4643 0.11756151-142 15 1.6215 0.0912415-154 15 1.6215 0.0912431-32 16 1.4153 0.13280

14 17 1.6854 0.12340147-77-07 18 1.2545 0.21360

13 19 1.4473 0.19620

This project :



Appendix C Snowmelt Analysis Worksheets


Calculate snowmelt during rain-on-snow events page 1JTS, 04/04/18 of 4

Snowmelt calculations for sub-basins within Eightmile Lake watershed

References :Corps of Engineers. Runoff from Snowmelt. EM 1110-2-1406. USACE. 1998.WSDOT. Hydraulics Manual. M 23-03. WSDOT. 2010. Section 2-4.1 on pages 2-5 to 2-6.

Key equations: % forest k SW rad Snowmelt = [( LW rad + Conv + rain melt ) ( Tair - 32 )] 0 1.0 0.07

+ [ SW rad + ground melt ] 10 1.0 0.0720 0.9 0.0730 0.8 0.07

where : Conv = 0.0084 k Vair ; k = f ( % forest cover ) 40 0.7 0.07use Vair = 18 mph 50 0.6 0.07checking : 80 % forest cover 60 0.5 0.07

Conv = 0.045 OK 70 0.4 0.0780 0.3 0.05

Rainmelt = 0.007 Pr 90 0.3 0.03100 0.3 0.03

coefficients :24-hr values : 18-hr values : 72-hr values :

LW rad 0.029 in. / day F 0.022 0.087Conv 0.0084 in. / day mph F 0.0063 0.0252rain melt 0.007 in. / in. F 0.007 0.007SW rad 0.07 in. / day 0.053 0.21grnd melt 0.02 in. / day 0.015 0.06

Calculation procedure :1) Identify elevation zones in increments of 1000 feet where snow may

occur. Determine area and % of sub-basin for each elevation zone. 2) Estimate snowpack depth and water content for each elevation zone

(represents upper limit for snowmelt runoff).3) Estimate air temperature for highest elevation. Estimate air temperature

lapse rate = 5.5 deg F per 1000 feet elevation change. Calculate average air temperature for each elevation zone.

4) Estimate R18 and R72 from design precipitation worksheets. Estimate typical wind velocity W from climatological data. If not available, estimate W = 18 mph.

5) Calculate M18 and M72 for each elevation zone. Calculate weighted average(weighted by % area) snowmelt depths M18 and M72 for the entire sub-basin.

6) Add snowmelt to rainfall to get total storm precipitation available for runoff.

Average January temperature = 26 deg F at Leavenworth, WAAverage March/April temperature 44 deg F at Leavenworth, WA



Snowmelt calculations for sub-basins within Eightmile Lake watershed

Snowmelt calculations for Eightmile Lake

Sub-basin drainage area = 6 acres / sq.milesHighest elevation = 7980 feet Temperature = 32.0 deg F

Average wind velocity = 17 miles/hourReservoir elevation = 4670 feet Temperature = 50.2 deg F

Zone 1 base elev. = 6500 feet Average temp. = 36.1 deg FZone 2 base elev. = 5500 feet Average temp. = 42.9 deg FZone 3 base elev. = 4500 feet Average temp. = 48.4 deg F

Frequency/design step: 10yr 25yr 50 yr 100 yr Step 1 Step 5 Step 7 Step 8Rainfall : Intermediate : R18 = 4.46 5.16 5.71 6.26 7.59 11.49 13.97 15.31 Long duration: R72 = 9.29 10.86 12.04 13.21 15.95 23.16 27.27 29.36

Elevation Zone 1 :Elevations = 6500 feet to 7980 feet

Zone drainage area = 1.93 acres / sq.miles forest cover = 10 % forest% of sub-basin = 32.2 % conv k = 1.0Air temperature = 36.1 deg F. SW rad = 0.07 in. / day

Snowpack depth = 10.0 feet = 120 inchesWater content = 20 % = 24.0 inches

Very little area above 6500ft burned

Frequency/design step : 10yr 25yr 50 yr 100 yr Step 1 Step 5 Step 7 Step 8 Snowmelt (inches):

Intermediate : M18 = 0.72 0.74 0.75 0.77 0.81 0.92 0.99 1.03% of snow water content = 3.0 3.1 3.1 3.2 3.4 3.8 4.1 4.3

revised M18 = 0.72 0.74 0.75 0.77 0.81 0.92 0.99 1.03weighted M18 = 0.231 0.238 0.243 0.248 0.260 0.296 0.318 0.331

Long duration: M72 = 2.63 2.68 2.71 2.74 2.82 3.03 3.14 3.20% of snow water content = 11.0 11.2 11.3 11.4 11.8 12.6 13.1 13.4













Estimated 30% of Zone 2 burned










Estimated 50% of Zone 2 burned




Snowmelt and design storm precipitation (in inches) for overall sub-basin :

Frequency/design step : 10yr 25yr 50 yr 100 yr Step 1 Step 5 Step 7 Step 8

Intermediate : M18 = 1.44 1.49 1.53 1.57 1.66 1.94 2.12 2.21 R18 = 4.46 5.16 5.71 6.26 7.59 11.49 13.97 15.31 P18 = 5.90 6.65 7.24 7.83 9.25 13.43 16.09 17.52

Long duration: M72 = 5.00 5.06 5.11 5.16 5.27 5.56 5.73 5.81 R72 = 9.29 10.86 12.04 13.21 15.95 23.16 27.27 29.36 P72 = 14.29 15.92 17.15 18.37 21.22 28.72 33.00 35.17

[end for this sub-basin]

Appendix D HEC-HMS Results

Project: EightmileLake Simulation Run: ExDamShort8PostBurnLowPool

Start of Run: 01Jan2017, 00:00 Basin Model: ExDamPostBurnShortCnLowPoolEnd of Run: 01Jan2017, 12:00 Meteorologic Model: ShortStep8Compute Time: 12Apr2018, 14:12:24 Control Specifications:Short

Hydrologic

Element

Drainage Area

(MI2)

Peak Discharge

(CFS)

Time of Peak Volume

(IN)

W290A 0.5900 449.6 01Jan2017, 02:40 4.22

W320 0.3380 304.0 01Jan2017, 02:30 4.15

W290B 0.0700 80.3 01Jan2017, 02:25 5.20

J49 0.9980 831.8 01Jan2017, 02:35 4.27

W340 0.7980 860.6 01Jan2017, 02:25 4.53

J30 0.7980 860.6 01Jan2017, 02:25 4.53

R10 0.7980 858.8 01Jan2017, 02:30 4.53

R130 1.7960 1687.8 01Jan2017, 02:35 4.38

W300 0.6350 416.4 01Jan2017, 02:45 3.68

W310 0.3699 378.8 01Jan2017, 02:25 4.27

J63 2.8009 2476.5 01Jan2017, 02:35 4.21

R110 2.8009 2473.0 01Jan2017, 02:40 4.20

W190A 0.1800 156.9 01Jan2017, 02:30 4.29

W190B 0.0400 56.7 01Jan2017, 02:20 4.27

J52 3.0209 2682.9 01Jan2017, 02:35 4.21

R80 3.0209 2681.9 01Jan2017, 02:40 4.21

W180A 0.9600 556.4 01Jan2017, 02:50 3.91

W200 0.8130 671.7 01Jan2017, 02:35 4.08

W180B 0.0200 45.0 01Jan2017, 02:10 4.87

J56 4.8139 3939.4 01Jan2017, 02:40 4.13

R30 4.8139 3936.7 01Jan2017, 02:40 4.13

W270 0.5670 567.8 01Jan2017, 02:25 4.32

W250 0.4530 207.9 01Jan2017, 02:50 3.22

Existing Dam 5.8339 274.4 01Jan2017, 10:35 0.47

Short8_LowPool_Global

Project: EightmileLake Simulation Run: ExDamShort8PostBurnLowPoolReservoir: Existing Dam

Start of Run: 01Jan2017, 00:00 Basin Model: ExDamPostBurnShoEnd of Run: 01Jan2017, 12:00 Meteorologic Model: ShortStep8Compute Time: 12Apr2018, 14:12:24 Control Specifications:Short

Date Time Inflow(CFS)

Storage(AC-FT)

Elevation(FT)

Outflow(CFS)

01Jan2017 00:00 0.0 1442.1 4648.6 0.0

01Jan2017 00:05 0.0 1442.1 4648.6 0.0

01Jan2017 00:10 0.0 1442.1 4648.6 0.0

01Jan2017 00:15 0.0 1442.1 4648.6 0.0

01Jan2017 00:20 0.2 1442.1 4648.6 0.0

01Jan2017 00:25 1.1 1442.1 4648.6 0.0

01Jan2017 00:30 3.3 1442.1 4648.7 0.0

01Jan2017 00:35 7.2 1442.2 4648.7 0.0

01Jan2017 00:40 12.5 1442.2 4648.7 0.0

01Jan2017 00:45 19.1 1442.3 4648.7 0.0

01Jan2017 00:50 26.8 1442.5 4648.7 0.0

01Jan2017 00:55 34.3 1442.7 4648.7 0.0

01Jan2017 01:00 39.8 1443.0 4648.7 0.0

01Jan2017 01:05 42.7 1443.2 4648.7 0.0

01Jan2017 01:10 43.4 1443.5 4648.7 0.0

01Jan2017 01:15 42.8 1443.8 4648.7 0.0

01Jan2017 01:20 42.1 1444.1 4648.7 0.0

01Jan2017 01:25 43.6 1444.4 4648.7 0.0

01Jan2017 01:30 50.4 1444.7 4648.7 0.0

01Jan2017 01:35 66.0 1445.1 4648.7 0.0

01Jan2017 01:40 96.6 1445.7 4648.7 0.0

01Jan2017 01:45 155.0 1446.6 4648.7 0.1

01Jan2017 01:50 259.0 1448.0 4648.8 0.1

01Jan2017 01:55 443.6 1450.4 4648.8 0.2

01Jan2017 02:00 808.3 1454.7 4648.9 0.4

01Jan2017 02:05 1434.3 1462.4 4649.1 1.0

Page 1

Short8_LowPool_timeTable 1


Storage(AC-FT)

Elevation(FT)

Outflow(CFS)

01Jan2017 02:10 2252.3 1475.1 4649.3 2.3

01Jan2017 02:15 3127.6 1493.6 4649.7 5.1

01Jan2017 02:20 3877.9 1517.7 4650.2 9.6

01Jan2017 02:25 4358.4 1546.0 4650.7 15.4

01Jan2017 02:30 4589.7 1576.7 4651.3 21.9

01Jan2017 02:35 4677.4 1608.4 4651.9 28.7

01Jan2017 02:40 4698.8 1640.5 4652.5 33.2

01Jan2017 02:45 4685.1 1672.5 4653.1 36.8

01Jan2017 02:50 4644.7 1704.4 4653.7 40.1

01Jan2017 02:55 4577.5 1735.9 4654.2 43.0

01Jan2017 03:00 4483.8 1766.8 4654.8 45.6

01Jan2017 03:05 4368.4 1796.9 4655.3 48.0

01Jan2017 03:10 4239.5 1826.2 4655.8 50.3

01Jan2017 03:15 4105.0 1854.6 4656.3 52.3

01Jan2017 03:20 3971.0 1882.1 4656.7 54.1

01Jan2017 03:25 3840.4 1908.6 4657.1 55.8

01Jan2017 03:30 3714.3 1934.2 4657.5 57.4

01Jan2017 03:35 3592.5 1959.0 4657.9 58.9

01Jan2017 03:40 3475.0 1982.9 4658.3 60.3

01Jan2017 03:45 3361.6 2006.0 4658.7 61.5

01Jan2017 03:50 3252.2 2028.4 4659.0 62.8

01Jan2017 03:55 3146.5 2050.0 4659.4 63.9

01Jan2017 04:00 3044.5 2070.8 4659.7 65.0

01Jan2017 04:05 2946.0 2091.0 4660.0 66.0

01Jan2017 04:10 2850.9 2110.5 4660.3 66.9

01Jan2017 04:15 2759.2 2129.4 4660.5 67.8

01Jan2017 04:20 2670.6 2147.6 4660.8 68.7

01Jan2017 04:25 2585.0 2165.2 4661.1 69.5

01Jan2017 04:30 2502.3 2182.3 4661.3 70.3

01Jan2017 04:35 2422.4 2198.7 4661.6 71.0

01Jan2017 04:40 2345.2 2214.7 4661.8 72.1

Page 2



Storage(AC-FT)

Elevation(FT)

Outflow(CFS)

01Jan2017 04:45 2270.6 2230.0 4662.0 75.3

01Jan2017 04:50 2198.4 2244.9 4662.2 79.4

01Jan2017 04:55 2128.4 2259.2 4662.4 84.2

01Jan2017 05:00 2060.8 2273.1 4662.6 89.3

01Jan2017 05:05 1995.4 2286.4 4662.8 94.7

01Jan2017 05:10 1932.2 2299.3 4663.0 100.3

01Jan2017 05:15 1871.2 2311.6 4663.2 106.0

01Jan2017 05:20 1812.3 2323.6 4663.3 111.8

01Jan2017 05:25 1755.3 2335.1 4663.5 117.6

01Jan2017 05:30 1700.1 2346.1 4663.6 123.4

01Jan2017 05:35 1646.8 2356.8 4663.8 129.1

01Jan2017 05:40 1595.2 2367.1 4663.9 134.8

01Jan2017 05:45 1545.3 2376.9 4664.1 140.5

01Jan2017 05:50 1497.1 2386.4 4664.2 146.0

01Jan2017 05:55 1450.5 2395.5 4664.3 151.4

01Jan2017 06:00 1405.5 2404.3 4664.4 156.8

01Jan2017 06:05 1361.9 2412.7 4664.5 162.0

01Jan2017 06:10 1319.7 2420.8 4664.6 167.1

01Jan2017 06:15 1279.0 2428.6 4664.7 172.1

01Jan2017 06:20 1239.6 2436.1 4664.9 176.9

01Jan2017 06:25 1201.5 2443.3 4664.9 181.6

01Jan2017 06:30 1164.6 2450.1 4665.0 186.2

01Jan2017 06:35 1128.9 2456.7 4665.1 190.6

01Jan2017 06:40 1094.3 2463.1 4665.2 194.9

01Jan2017 06:45 1060.9 2469.1 4665.3 199.1

01Jan2017 06:50 1028.7 2474.9 4665.4 203.1

01Jan2017 06:55 997.4 2480.5 4665.4 207.0

01Jan2017 07:00 967.2 2485.8 4665.5 210.8

01Jan2017 07:05 937.9 2490.9 4665.6 214.4

01Jan2017 07:10 909.6 2495.8 4665.6 217.8

01Jan2017 07:15 882.2 2500.5 4665.7 221.2

Page 3



Storage(AC-FT)

Elevation(FT)

Outflow(CFS)

01Jan2017 07:20 855.7 2504.9 4665.8 224.4

01Jan2017 07:25 830.1 2509.2 4665.8 227.5

01Jan2017 07:30 805.2 2513.2 4665.9 230.4

01Jan2017 07:35 781.2 2517.1 4665.9 233.3

01Jan2017 07:40 757.9 2520.8 4666.0 236.0

01Jan2017 07:45 735.4 2524.3 4666.0 238.6

01Jan2017 07:50 713.5 2527.6 4666.1 241.1

01Jan2017 07:55 692.4 2530.8 4666.1 243.5

01Jan2017 08:00 671.9 2533.8 4666.1 245.7

01Jan2017 08:05 652.1 2536.7 4666.2 247.9

01Jan2017 08:10 632.9 2539.4 4666.2 249.9

01Jan2017 08:15 614.3 2541.9 4666.3 251.9

01Jan2017 08:20 596.3 2544.4 4666.3 253.7

01Jan2017 08:25 578.8 2546.7 4666.3 255.5

01Jan2017 08:30 561.9 2548.8 4666.3 257.1

01Jan2017 08:35 545.5 2550.9 4666.4 258.7

01Jan2017 08:40 529.6 2552.8 4666.4 260.1

01Jan2017 08:45 514.3 2554.6 4666.4 261.5

01Jan2017 08:50 499.3 2556.3 4666.4 262.8

01Jan2017 08:55 484.9 2557.8 4666.5 264.0

01Jan2017 09:00 470.9 2559.3 4666.5 265.2

01Jan2017 09:05 457.2 2560.7 4666.5 266.2

01Jan2017 09:10 444.0 2561.9 4666.5 267.2

01Jan2017 09:15 431.2 2563.1 4666.5 268.1

01Jan2017 09:20 418.8 2564.2 4666.5 268.9

01Jan2017 09:25 406.9 2565.2 4666.6 269.7

01Jan2017 09:30 395.3 2566.1 4666.6 270.4

01Jan2017 09:35 384.0 2566.9 4666.6 271.0

01Jan2017 09:40 373.1 2567.6 4666.6 271.6

01Jan2017 09:45 362.5 2568.3 4666.6 272.1

01Jan2017 09:50 352.3 2568.9 4666.6 272.6

Page 4



Storage(AC-FT)

Elevation(FT)

Outflow(CFS)

01Jan2017 09:55 342.3 2569.4 4666.6 273.0

01Jan2017 10:00 332.7 2569.8 4666.6 273.3

01Jan2017 10:05 323.3 2570.2 4666.6 273.6

01Jan2017 10:10 314.3 2570.5 4666.6 273.9

01Jan2017 10:15 305.5 2570.8 4666.6 274.1

01Jan2017 10:20 296.9 2571.0 4666.6 274.2

01Jan2017 10:25 288.7 2571.1 4666.6 274.3

01Jan2017 10:30 280.6 2571.2 4666.6 274.4

01Jan2017 10:35 272.8 2571.2 4666.6 274.4

01Jan2017 10:40 265.3 2571.1 4666.6 274.4

01Jan2017 10:45 257.9 2571.0 4666.6 274.3

01Jan2017 10:50 250.8 2570.9 4666.6 274.2

01Jan2017 10:55 243.9 2570.7 4666.6 274.0

01Jan2017 11:00 237.2 2570.5 4666.6 273.9

01Jan2017 11:05 230.7 2570.2 4666.6 273.6

01Jan2017 11:10 224.4 2569.9 4666.6 273.4

01Jan2017 11:15 218.2 2569.5 4666.6 273.1

01Jan2017 11:20 212.3 2569.1 4666.6 272.8

01Jan2017 11:25 206.5 2568.7 4666.6 272.5

01Jan2017 11:30 200.8 2568.2 4666.6 272.1

01Jan2017 11:35 195.3 2567.7 4666.6 271.7

01Jan2017 11:40 190.0 2567.2 4666.6 271.3

01Jan2017 11:45 184.9 2566.6 4666.6 270.8

01Jan2017 11:50 179.9 2566.0 4666.6 270.4

01Jan2017 11:55 175.0 2565.4 4666.6 269.9

01Jan2017 12:00 170.3 2564.7 4666.6 269.3

Page 5


E l e v ( f t )

4,648

4,650

4,652

4,654

4,656

4,658

4,660

4,662

4,664

4,666

4,668

00:00 02:00 04:00 06:00 08:00 10:00 12:00

01Jan2017

F l o w ( c f s )

0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

4,500

5,000

Existing Dam

Run:ExDamShort8PostBurnLowPool Element:Existing Dam Result:Pool Elevation Run:ExDamShort8PostBurnLowPool Element:Existing Dam-DAMTOP-1 Result:Dam Top 1

Run:ExDamShort8PostBurnLowPool Element:Existing Dam-SPILL-1 Result:Spillway 1 Run:ExDamShort8PostBurnLowPool Element:Existing Dam-OUTLET-1 Result:Outlet 1

Run:ExDamShort8PostBurnLowPool Element:Existing Dam Result:Combined Inflow Run:ExDamShort8PostBurnLowPool Element:Existing Dam Result:Outflow

Short8_LowPool_Graph

Project: EightmileLake Simulation Run: ExInt8LowPoolBurn

Start of Run: 01Jan2017, 00:00 Basin Model: ExDamPostBurnLowEnd of Run: 02Jan2017, 12:00 Meteorologic Model: Inter8SnowmeltCompute Time: 30Apr2018, 09:48:18 Control Specifications:Intermediate

HydrologicElement

Drainage Area(MI2)

Peak Discharge(CFS)

Time of Peak Volume(AC-FT)

W290A 0.59 599.6 01Jan2017, 14:45 477.6

W320 0.338 377.2 01Jan2017, 14:15 268.9

W290B 0.07 81.4 01Jan2017, 14:15 59.4

J49 0.998 1056.0 01Jan2017, 14:15 805.9

W340 0.798 940.9 01Jan2017, 14:15 653.2

J30 0.798 940.9 01Jan2017, 14:15 653.2

R10 0.798 939.8 01Jan2017, 14:15 653.2

R130 1.796 1987.2 01Jan2017, 14:30 1459.2

W300 0.635 628.9 01Jan2017, 15:00 486.6

W310 0.3699 434.9 01Jan2017, 14:15 297.5

J63 2.8009 3045.4 01Jan2017, 14:15 2243.3

R110 2.8009 3043.3 01Jan2017, 14:30 2243.4

W190A 0.18 195.2 01Jan2017, 14:15 145.7

W190B 0.04 55.6 01Jan2017, 14:00 34.1

J52 3.0209 3290.0 01Jan2017, 14:30 2423.2

R80 3.0209 3289.3 01Jan2017, 14:30 2423.4

W180A 0.96 871.8 01Jan2017, 15:30 769.5

W200 0.813 885.6 01Jan2017, 14:15 663.1

W180B 0.02 32.4 01Jan2017, 13:45 17.7

J56 4.8139 5053.3 01Jan2017, 14:30 3873.6

R30 4.8139 5051.6 01Jan2017, 14:30 3873.6

W270 0.567 654.5 01Jan2017, 14:15 454.6

W250 0.453 383.5 01Jan2017, 15:30 330.6

Existing Dam 5.8339 4678.1 01Jan2017, 17:00 3570.0

Int8_LowPool_Global

Project: EightmileLake Simulation Run: ExInt8LowPoolBurnReservoir: Existing Dam



Storage(AC-FT)

Elevation(FT)

Outflow(CFS)

01Jan2017 00:00 0.0 1442.1 4648.6 0.0

01Jan2017 00:15 0.0 1442.1 4648.6 0.0

01Jan2017 00:30 0.0 1442.1 4648.6 0.0

01Jan2017 00:45 0.0 1442.1 4648.6 0.0

01Jan2017 01:00 0.1 1442.1 4648.6 0.0

01Jan2017 01:15 0.3 1442.1 4648.6 0.0

01Jan2017 01:30 0.7 1442.1 4648.6 0.0

01Jan2017 01:45 1.7 1442.1 4648.7 0.0

01Jan2017 02:00 5.2 1442.2 4648.7 0.0

01Jan2017 02:15 14.1 1442.4 4648.7 0.0

01Jan2017 02:30 30.9 1442.9 4648.7 0.0

01Jan2017 02:45 58.1 1443.8 4648.7 0.0

01Jan2017 03:00 98.4 1445.4 4648.7 0.0

01Jan2017 03:15 152.7 1448.0 4648.8 0.1

01Jan2017 03:30 221.3 1451.9 4648.8 0.2

01Jan2017 03:45 304.2 1457.3 4649.0 0.6

01Jan2017 04:00 397.5 1464.5 4649.1 1.1

01Jan2017 04:15 498.7 1473.7 4649.3 2.2

01Jan2017 04:30 608.3 1485.1 4649.5 3.7

01Jan2017 04:45 726.5 1498.8 4649.8 6.0

01Jan2017 05:00 852.4 1514.9 4650.1 9.0

01Jan2017 05:15 985.4 1533.7 4650.5 12.8

01Jan2017 05:30 1124.4 1555.2 4650.9 17.3

01Jan2017 05:45 1272.2 1579.5 4651.4 22.5

01Jan2017 06:00 1437.0 1607.0 4651.9 28.4

01Jan2017 06:15 1624.9 1638.0 4652.5 32.9

Page 1

Int8_LowPool_TimeTablel 1


Storage(AC-FT)

Elevation(FT)

Outflow(CFS)

01Jan2017 06:30 1845.1 1673.1 4653.1 36.9

01Jan2017 06:45 2111.4 1713.2 4653.8 40.9

01Jan2017 07:00 2383.7 1758.7 4654.6 45.0

01Jan2017 07:15 2598.9 1809.2 4655.5 49.0

01Jan2017 07:30 2747.8 1863.4 4656.4 52.9

01Jan2017 07:45 2842.4 1920.0 4657.3 56.5

01Jan2017 08:00 2894.9 1978.1 4658.2 60.0

01Jan2017 08:15 2915.7 2036.9 4659.2 63.2

01Jan2017 08:30 2909.9 2095.7 4660.0 66.2

01Jan2017 08:45 2880.3 2154.1 4660.9 69.0

01Jan2017 09:00 2833.1 2211.7 4661.7 71.7

01Jan2017 09:15 2771.6 2268.0 4662.5 87.3

01Jan2017 09:30 2693.1 2322.4 4663.3 111.2

01Jan2017 09:45 2601.6 2374.5 4664.0 139.1

01Jan2017 10:00 2507.7 2424.1 4664.7 169.2

01Jan2017 10:15 2424.0 2471.2 4665.3 200.5

01Jan2017 10:30 2354.2 2516.1 4665.9 232.6

01Jan2017 10:45 2298.0 2559.0 4666.5 265.0

01Jan2017 11:00 2258.4 2600.3 4667.0 297.7

01Jan2017 11:15 2244.1 2640.1 4667.5 358.9

01Jan2017 11:30 2290.2 2678.7 4668.0 440.4

01Jan2017 11:45 2416.1 2717.2 4668.5 536.0

01Jan2017 12:00 2601.6 2756.8 4669.0 646.4

01Jan2017 12:15 2825.2 2798.2 4669.5 772.8

01Jan2017 12:30 3069.4 2841.7 4670.1 916.0

01Jan2017 12:45 3318.2 2887.1 4670.6 1076.0

01Jan2017 13:00 3583.4 2934.3 4671.2 1252.5

01Jan2017 13:15 3927.4 2984.0 4671.8 1448.1

01Jan2017 13:30 4594.1 3039.7 4672.5 1678.7

01Jan2017 13:45 5369.4 3105.0 4673.3 1962.4

01Jan2017 14:00 5836.3 3176.9 4674.1 2289.7

Page 2



Storage(AC-FT)

Elevation(FT)

Outflow(CFS)

01Jan2017 14:15 6033.7 3248.6 4675.0 2631.2

01Jan2017 14:30 6068.1 3315.8 4675.8 2962.9

01Jan2017 14:45 6053.4 3376.6 4676.5 3272.1

01Jan2017 15:00 6022.9 3430.8 4677.1 3554.6

01Jan2017 15:15 5973.8 3478.6 4677.6 3809.0

01Jan2017 15:30 5904.4 3520.3 4678.1 4034.2

01Jan2017 15:45 5811.1 3555.9 4678.5 4229.6

01Jan2017 16:00 5671.6 3585.5 4678.8 4393.5

01Jan2017 16:15 5476.0 3608.5 4679.1 4522.7

01Jan2017 16:30 5221.5 3624.6 4679.3 4613.7

01Jan2017 16:45 4929.1 3633.6 4679.4 4664.8

01Jan2017 17:00 4640.5 3636.0 4679.4 4678.1

01Jan2017 17:15 4369.5 3632.6 4679.4 4658.9

01Jan2017 17:30 4121.8 3624.5 4679.3 4613.2

01Jan2017 17:45 3893.0 3612.7 4679.1 4546.4

01Jan2017 18:00 3679.7 3597.9 4679.0 4463.0

01Jan2017 18:15 3440.8 3580.2 4678.8 4364.4

01Jan2017 18:30 3162.0 3559.5 4678.6 4249.1

01Jan2017 18:45 2885.6 3535.5 4678.3 4117.2

01Jan2017 19:00 2629.1 3508.9 4678.0 3972.2

01Jan2017 19:15 2395.9 3480.3 4677.7 3818.1

01Jan2017 19:30 2184.5 3450.4 4677.3 3658.5

01Jan2017 19:45 1992.7 3419.7 4677.0 3496.3

01Jan2017 20:00 1818.7 3388.5 4676.6 3333.8

01Jan2017 20:15 1660.8 3357.3 4676.2 3173.0

01Jan2017 20:30 1517.4 3326.2 4675.9 3015.2

01Jan2017 20:45 1387.2 3295.5 4675.5 2861.7

01Jan2017 21:00 1268.9 3265.4 4675.2 2713.0

01Jan2017 21:15 1161.3 3236.0 4674.8 2570.0

01Jan2017 21:30 1063.4 3207.3 4674.5 2432.8

01Jan2017 21:45 974.2 3179.4 4674.2 2301.7

Page 3



Storage(AC-FT)

Elevation(FT)

Outflow(CFS)

01Jan2017 22:00 892.8 3152.5 4673.8 2176.8

01Jan2017 22:15 818.5 3126.4 4673.5 2058.1

01Jan2017 22:30 750.6 3101.3 4673.2 1945.5

01Jan2017 22:45 688.4 3077.0 4672.9 1838.9

01Jan2017 23:00 631.6 3053.7 4672.7 1738.1

01Jan2017 23:15 579.6 3031.3 4672.4 1643.0

01Jan2017 23:30 532.0 3009.8 4672.1 1553.2

01Jan2017 23:45 488.4 2989.1 4671.9 1468.6

02Jan2017 00:00 448.3 2969.2 4671.6 1388.9

02Jan2017 00:15 411.1 2950.2 4671.4 1313.8

02Jan2017 00:30 376.8 2931.9 4671.2 1243.2

02Jan2017 00:45 345.1 2914.4 4671.0 1176.7

02Jan2017 01:00 316.6 2897.5 4670.8 1114.2

02Jan2017 01:15 290.7 2881.4 4670.6 1055.4

02Jan2017 01:30 267.0 2865.9 4670.4 1000.1

02Jan2017 01:45 245.1 2851.1 4670.2 948.3

02Jan2017 02:00 225.0 2836.9 4670.0 899.6

02Jan2017 02:15 206.6 2823.2 4669.8 853.8

02Jan2017 02:30 189.6 2810.1 4669.7 810.8

02Jan2017 02:45 173.9 2797.5 4669.5 770.5

02Jan2017 03:00 159.0 2785.4 4669.4 732.5

02Jan2017 03:15 145.9 2773.8 4669.2 696.9

02Jan2017 03:30 133.9 2762.7 4669.1 663.5

02Jan2017 03:45 123.0 2751.9 4669.0 632.1

02Jan2017 04:00 112.9 2741.6 4668.8 602.6

02Jan2017 04:15 103.6 2731.7 4668.7 575.0

02Jan2017 04:30 95.0 2722.1 4668.6 549.1

02Jan2017 04:45 87.1 2712.9 4668.5 524.7

02Jan2017 05:00 79.7 2704.0 4668.3 501.9

02Jan2017 05:15 72.9 2695.5 4668.2 480.5

02Jan2017 05:30 66.7 2687.2 4668.1 460.4

Page 4



Storage(AC-FT)

Elevation(FT)

Outflow(CFS)

02Jan2017 05:45 61.0 2679.2 4668.0 441.5

02Jan2017 06:00 55.9 2671.4 4667.9 423.9

02Jan2017 06:15 51.3 2664.0 4667.8 407.4

02Jan2017 06:30 47.1 2656.7 4667.7 392.0

02Jan2017 06:45 43.4 2649.7 4667.7 377.7

02Jan2017 07:00 39.9 2642.9 4667.6 364.3

02Jan2017 07:15 36.7 2636.3 4667.5 351.9

02Jan2017 07:30 33.7 2629.9 4667.4 340.4

02Jan2017 07:45 31.1 2623.6 4667.3 329.8

02Jan2017 08:00 28.7 2617.5 4667.2 320.2

02Jan2017 08:15 26.6 2611.6 4667.2 311.5

02Jan2017 08:30 24.5 2605.7 4667.1 303.8

02Jan2017 08:45 22.6 2600.0 4667.0 297.4

02Jan2017 09:00 20.7 2594.4 4666.9 292.7

02Jan2017 09:15 19.0 2588.8 4666.9 288.3

02Jan2017 09:30 17.4 2583.2 4666.8 283.9

02Jan2017 09:45 15.9 2577.8 4666.7 279.6

02Jan2017 10:00 14.5 2572.3 4666.7 275.3

02Jan2017 10:15 13.0 2567.0 4666.6 271.1

02Jan2017 10:30 11.3 2561.7 4666.5 267.0

02Jan2017 10:45 10.0 2556.4 4666.4 262.9

02Jan2017 11:00 8.8 2551.2 4666.4 258.9

02Jan2017 11:15 7.9 2546.1 4666.3 255.0

02Jan2017 11:30 7.0 2541.0 4666.2 251.2

02Jan2017 11:45 6.1 2536.0 4666.2 247.4

02Jan2017 12:00 5.3 2531.0 4666.1 243.6

Page 5


E l e v ( f t )

4,645

4,650

4,655

4,660

4,665

4,670

4,675

4,680

00:00 06:00 12:00 18:00 00:00 06:00 12:00

01Jan2017 02Jan2017

F l o w ( c f s )

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

Existing Dam

Run:ExInt8LowPoolBurn Element:Existing Dam Result:Pool Elevation Run:ExInt8LowPoolBurn Element:Existing Dam-DAMTOP-1 Result:Dam Top 1

Run:ExInt8LowPoolBurn Element:Existing Dam-SPILL-1 Result:Spillway 1 Run:ExInt8LowPoolBurn Element:Existing Dam-OUTLET-1 Result:Outlet 1

Run:ExInt8LowPoolBurn Element:Existing Dam Result:Combined Inflow Run:ExInt8LowPoolBurn Element:Existing Dam Result:Outflow

Int8_LowPool_Graph

Project: EightmileLake Simulation Run: ExDamInt10yrPostBurnLowPool

Start of Run: 01Jan2017, 00:00 Basin Model: ExDamPostBurnLowPoolEnd of Run: 02Jan2017, 12:00 Meteorologic Model: Int10yrSnowCompute Time: 12Apr2018, 11:28:42 Control Specifications:Intermediate

HydrologicElement

Drainage Area(MI2)

Peak Discharge(CFS)


W290A 0.59 71.1 01Jan2017, 15:30 46.2

W320 0.338 40.8 01Jan2017, 15:15 22.1

W290B 0.07 11.2 01Jan2017, 14:15 7.0

J49 0.998 315.8 01Jan2017, 14:45 215.7

W340 0.798 114.3 01Jan2017, 15:00 66.1

J30 0.798 288.2 01Jan2017, 14:15 180.0

R10 0.798 287.4 01Jan2017, 14:15 180.0

R130 1.796 601.7 01Jan2017, 14:30 395.8

W300 0.635 55.5 01Jan2017, 15:45 30.8

W310 0.3699 49.3 01Jan2017, 15:00 26.7

J63 2.8009 902.6 01Jan2017, 14:30 589.5

R110 2.8009 901.6 01Jan2017, 14:45 589.6

W190A 0.18 23.1 01Jan2017, 15:15 14.1

W190B 0.04 7.9 01Jan2017, 14:00 4.1

J52 3.0209 977.0 01Jan2017, 14:30 639.1

R80 3.0209 976.6 01Jan2017, 14:45 639.1

W180A 0.96 98.4 01Jan2017, 15:45 71.6

Page 1

Int10yr_LowPool_Global 1

HydrologicElement

Drainage Area(MI2)

Peak Discharge(CFS)


W200 0.813 105.4 01Jan2017, 15:15 58.9

W180B 0.02 5.1 01Jan2017, 14:00 2.5

J56 4.8139 1506.6 01Jan2017, 14:45 1026.8

R30 4.8139 1506.3 01Jan2017, 14:45 1026.8

W270 0.567 74.3 01Jan2017, 15:00 42.3

W250 0.453 26.4 01Jan2017, 16:15 17.3

Existing Dam 5.8339 218.1 01Jan2017, 22:45 307.6

Page 2

Int10yr_LowPool_Global 2

Project: EightmileLake Simulation Run: ExDamInt10yrPostBurnLowPoolReservoir: Existing Dam

Start of Run: 01Jan2017, 00:00 Basin Model: ExDamPostBurnLowEnd of Run: 02Jan2017, 12:00 Meteorologic Model: Int10yrSnowCompute Time: 12Apr2018, 11:28:42 Control Specifications:Intermediate


Storage(AC-FT)

Elevation(FT)

Outflow(CFS)

01Jan2017 00:00 0.0 1442.1 4648.6 0.0

01Jan2017 00:15 0.0 1442.1 4648.6 0.0

01Jan2017 00:30 0.0 1442.1 4648.6 0.0

01Jan2017 00:45 0.0 1442.1 4648.6 0.0

01Jan2017 01:00 0.0 1442.1 4648.6 0.0

01Jan2017 01:15 0.0 1442.1 4648.6 0.0

01Jan2017 01:30 0.0 1442.1 4648.6 0.0

01Jan2017 01:45 0.0 1442.1 4648.6 0.0

01Jan2017 02:00 0.1 1442.1 4648.6 0.0

01Jan2017 02:15 0.1 1442.1 4648.6 0.0

01Jan2017 02:30 0.3 1442.1 4648.6 0.0

01Jan2017 02:45 0.4 1442.1 4648.6 0.0

01Jan2017 03:00 0.7 1442.1 4648.6 0.0

01Jan2017 03:15 1.1 1442.1 4648.6 0.0

01Jan2017 03:30 2.0 1442.1 4648.7 0.0

01Jan2017 03:45 4.0 1442.2 4648.7 0.0

01Jan2017 04:00 8.1 1442.3 4648.7 0.0

01Jan2017 04:15 14.3 1442.6 4648.7 0.0

01Jan2017 04:30 23.1 1442.9 4648.7 0.0

01Jan2017 04:45 34.7 1443.5 4648.7 0.0

01Jan2017 05:00 49.0 1444.4 4648.7 0.0

01Jan2017 05:15 67.3 1445.6 4648.7 0.0

01Jan2017 05:30 89.9 1447.2 4648.8 0.1

01Jan2017 05:45 115.6 1449.3 4648.8 0.1

01Jan2017 06:00 145.2 1452.0 4648.9 0.3

01Jan2017 06:15 182.7 1455.4 4648.9 0.4

Page 1

Int10yr_LowPool_TimeTablel 1


Storage(AC-FT)

Elevation(FT)

Outflow(CFS)

01Jan2017 06:30 231.0 1459.7 4649.0 0.7

01Jan2017 06:45 291.8 1465.1 4649.1 1.2

01Jan2017 07:00 358.7 1471.8 4649.3 1.9

01Jan2017 07:15 420.6 1479.8 4649.4 3.0

01Jan2017 07:30 471.1 1488.9 4649.6 4.3

01Jan2017 07:45 507.7 1498.9 4649.8 6.0

01Jan2017 08:00 535.1 1509.5 4650.0 8.0

01Jan2017 08:15 555.9 1520.6 4650.2 10.1

01Jan2017 08:30 571.4 1532.0 4650.5 12.5

01Jan2017 08:45 582.0 1543.6 4650.7 14.9

01Jan2017 09:00 585.0 1555.4 4650.9 17.4

01Jan2017 09:15 582.2 1567.0 4651.1 19.8

01Jan2017 09:30 574.8 1578.6 4651.3 22.3

01Jan2017 09:45 563.5 1589.8 4651.6 24.7

01Jan2017 10:00 551.6 1600.8 4651.8 27.0

01Jan2017 10:15 540.5 1611.5 4652.0 29.3

01Jan2017 10:30 530.9 1622.0 4652.2 30.9

01Jan2017 10:45 525.6 1632.2 4652.4 32.2

01Jan2017 11:00 525.7 1642.4 4652.5 33.4

01Jan2017 11:15 531.6 1652.6 4652.7 34.6

01Jan2017 11:30 552.0 1663.1 4652.9 35.8

01Jan2017 11:45 594.1 1674.2 4653.1 37.0

01Jan2017 12:00 653.4 1686.3 4653.3 38.3

01Jan2017 12:15 723.7 1699.7 4653.6 39.6

01Jan2017 12:30 798.3 1714.6 4653.9 41.1

01Jan2017 12:45 874.3 1731.0 4654.1 42.6

01Jan2017 13:00 958.0 1749.1 4654.5 44.2

01Jan2017 13:15 1066.2 1769.0 4654.8 45.8

01Jan2017 13:30 1268.1 1792.2 4655.2 47.7

01Jan2017 13:45 1510.7 1819.9 4655.7 49.8

01Jan2017 14:00 1673.6 1851.7 4656.2 52.1

Page 2



Storage(AC-FT)

Elevation(FT)

Outflow(CFS)

01Jan2017 14:15 1754.5 1886.0 4656.8 54.4

01Jan2017 14:30 1782.4 1921.4 4657.3 56.6

01Jan2017 14:45 1789.1 1957.1 4657.9 58.8

01Jan2017 15:00 1786.9 1992.8 4658.5 60.8

01Jan2017 15:15 1779.2 2028.4 4659.0 62.8

01Jan2017 15:30 1766.8 2063.7 4659.6 64.6

01Jan2017 15:45 1750.2 2098.7 4660.1 66.3

01Jan2017 16:00 1717.8 2133.1 4660.6 68.0

01Jan2017 16:15 1665.7 2166.7 4661.1 69.6

01Jan2017 16:30 1593.9 2198.9 4661.6 71.0

01Jan2017 16:45 1507.9 2229.4 4662.0 75.2

01Jan2017 17:00 1422.3 2258.1 4662.4 83.8

01Jan2017 17:15 1342.8 2284.8 4662.8 94.0

01Jan2017 17:30 1270.8 2309.7 4663.1 105.1

01Jan2017 17:45 1202.0 2333.0 4663.4 116.5

01Jan2017 18:00 1134.2 2354.6 4663.7 127.9

01Jan2017 18:15 1059.3 2374.5 4664.0 139.1

01Jan2017 18:30 974.2 2392.5 4664.3 149.7

01Jan2017 18:45 889.6 2408.6 4664.5 159.4

01Jan2017 19:00 810.2 2422.8 4664.7 168.3

01Jan2017 19:15 737.7 2435.2 4664.8 176.3

01Jan2017 19:30 672.0 2446.1 4665.0 183.5

01Jan2017 19:45 612.5 2455.5 4665.1 189.8

01Jan2017 20:00 558.6 2463.6 4665.2 195.3

01Jan2017 20:15 509.6 2470.5 4665.3 200.1

01Jan2017 20:30 465.3 2476.4 4665.4 204.2

01Jan2017 20:45 425.0 2481.4 4665.5 207.6

01Jan2017 21:00 388.4 2485.5 4665.5 210.5

01Jan2017 21:15 355.2 2488.8 4665.6 212.8

01Jan2017 21:30 325.0 2491.4 4665.6 214.7

01Jan2017 21:45 297.5 2493.4 4665.6 216.1

Page 3



Storage(AC-FT)

Elevation(FT)

Outflow(CFS)

01Jan2017 22:00 272.4 2494.8 4665.6 217.1

01Jan2017 22:15 249.6 2495.7 4665.6 217.7

01Jan2017 22:30 228.7 2496.1 4665.7 218.1

01Jan2017 22:45 209.6 2496.1 4665.7 218.1

01Jan2017 23:00 192.2 2495.8 4665.6 217.8

01Jan2017 23:15 176.3 2495.1 4665.6 217.3

01Jan2017 23:30 161.7 2494.1 4665.6 216.6

01Jan2017 23:45 148.4 2492.8 4665.6 215.7

02Jan2017 00:00 136.1 2491.3 4665.6 214.6

02Jan2017 00:15 124.8 2489.6 4665.6 213.4

02Jan2017 00:30 114.3 2487.7 4665.5 212.1

02Jan2017 00:45 104.6 2485.6 4665.5 210.6

02Jan2017 01:00 95.8 2483.3 4665.5 209.0

02Jan2017 01:15 87.9 2480.9 4665.4 207.3

02Jan2017 01:30 80.7 2478.4 4665.4 205.5

02Jan2017 01:45 74.0 2475.8 4665.4 203.7

02Jan2017 02:00 67.9 2473.0 4665.3 201.8

02Jan2017 02:15 62.3 2470.2 4665.3 199.9

02Jan2017 02:30 57.1 2467.4 4665.3 197.9

02Jan2017 02:45 52.3 2464.4 4665.2 195.9

02Jan2017 03:00 47.8 2461.4 4665.2 193.8

02Jan2017 03:15 43.8 2458.4 4665.1 191.8

02Jan2017 03:30 40.2 2455.3 4665.1 189.7

02Jan2017 03:45 36.9 2452.2 4665.1 187.6

02Jan2017 04:00 33.8 2449.1 4665.0 185.5

02Jan2017 04:15 31.1 2446.0 4665.0 183.4

02Jan2017 04:30 28.5 2442.8 4664.9 181.3

02Jan2017 04:45 26.1 2439.6 4664.9 179.2

02Jan2017 05:00 23.9 2436.5 4664.9 177.2

02Jan2017 05:15 21.9 2433.3 4664.8 175.1

02Jan2017 05:30 20.0 2430.1 4664.8 173.1

Page 4



Storage(AC-FT)

Elevation(FT)

Outflow(CFS)

02Jan2017 05:45 18.3 2427.0 4664.7 171.0

02Jan2017 06:00 16.8 2423.8 4664.7 169.0

02Jan2017 06:15 15.4 2420.7 4664.6 167.0

02Jan2017 06:30 14.1 2417.6 4664.6 165.0

02Jan2017 06:45 13.0 2414.5 4664.6 163.1

02Jan2017 07:00 11.9 2411.4 4664.5 161.2

02Jan2017 07:15 11.0 2408.3 4664.5 159.2

02Jan2017 07:30 10.1 2405.2 4664.4 157.4

02Jan2017 07:45 9.3 2402.2 4664.4 155.5

02Jan2017 08:00 8.6 2399.2 4664.4 153.7

02Jan2017 08:15 7.9 2396.2 4664.3 151.9

02Jan2017 08:30 7.3 2393.2 4664.3 150.1

02Jan2017 08:45 6.7 2390.3 4664.2 148.3

02Jan2017 09:00 6.1 2387.4 4664.2 146.6

02Jan2017 09:15 5.6 2384.5 4664.2 144.9

02Jan2017 09:30 5.2 2381.6 4664.1 143.2

02Jan2017 09:45 4.7 2378.8 4664.1 141.6

02Jan2017 10:00 4.3 2376.0 4664.0 139.9

02Jan2017 10:15 3.9 2373.2 4664.0 138.3

02Jan2017 10:30 3.4 2370.4 4664.0 136.7

02Jan2017 10:45 3.0 2367.7 4663.9 135.2

02Jan2017 11:00 2.6 2365.0 4663.9 133.7

02Jan2017 11:15 2.4 2362.3 4663.9 132.2

02Jan2017 11:30 2.1 2359.6 4663.8 130.7

02Jan2017 11:45 1.8 2357.0 4663.8 129.2

02Jan2017 12:00 1.6 2354.3 4663.7 127.8

Page 5


E l e v ( f t )

4,648

4,650

4,652

4,654

4,656

4,658

4,660

4,662

4,664

4,666

00:00 06:00 12:00 18:00 00:00 06:00 12:00

01Jan2017 02Jan2017

F l o w ( c f s )

0

200

400

600

800

1,000

1,200

1,400

1,600

1,800

2,000

Existing Dam

Run:ExDamInt10yrPostBurnLowPool Element:Existing Dam Result:Pool Elevation Run:ExDamInt10yrPostBurnLowPool Element:Existing Dam-DAMTOP-1 Result:Dam Top 1

Run:ExDamInt10yrPostBurnLowPool Element:Existing Dam-SPILL-1 Result:Spillway 1 Run:ExDamInt10yrPostBurnLowPool Element:Existing Dam-OUTLET-1 Result:Outlet 1

Run:ExDamInt10yrPostBurnLowPool Element:Existing Dam Result:Combined Inflow Run:ExDamInt10yrPostBurnLowPool Element:Existing Dam Result:Outflow

Int10yr_LowPool_Graph

Project: EightmileLake Simulation Run: ExDamShort8PostBurnNormPool

Start of Run: 01Jan2017, 00:00 Basin Model: ExDamPostBurnShortCNNormPoolEnd of Run: 01Jan2017, 12:00 Meteorologic Model: ShortStep8Compute Time: 12Apr2018, 14:12:41 Control Specifications:Short

HydrologicElement

Drainage Area(MI2)

Peak Discharge(CFS)


W290A 0.59 449.6 01Jan2017, 02:40 132.8

W320 0.338 304.0 01Jan2017, 02:30 74.9

W290B 0.07 80.3 01Jan2017, 02:25 19.4

J49 0.998 831.8 01Jan2017, 02:35 227.1

W340 0.798 860.6 01Jan2017, 02:25 192.9

J30 0.798 860.6 01Jan2017, 02:25 192.9

R10 0.798 858.8 01Jan2017, 02:30 192.8

R130 1.796 1687.8 01Jan2017, 02:35 419.5

W300 0.635 416.4 01Jan2017, 02:45 124.5

W310 0.3699 378.8 01Jan2017, 02:25 84.3

J63 2.8009 2476.5 01Jan2017, 02:35 628.2

R110 2.8009 2473.0 01Jan2017, 02:40 628.0

W190A 0.18 156.9 01Jan2017, 02:30 41.2

W190B 0.04 56.7 01Jan2017, 02:20 9.1

J52 3.0209 2682.9 01Jan2017, 02:35 678.3

R80 3.0209 2681.9 01Jan2017, 02:40 677.8

W180A 0.96 556.4 01Jan2017, 02:50 200.2

Page 1

Short8_normalPool_Global 1

HydrologicElement

Drainage Area(MI2)

Peak Discharge(CFS)


W200 0.813 671.7 01Jan2017, 02:35 176.8

W180B 0.02 45.0 01Jan2017, 02:10 5.2

J56 4.8139 3939.4 01Jan2017, 02:40 1060.0

R30 4.8139 3936.7 01Jan2017, 02:40 1059.8

W270 0.567 567.8 01Jan2017, 02:25 130.6

W250 0.453 207.9 01Jan2017, 02:50 77.7

Existing Dam 5.8339 1314.5 01Jan2017, 06:10 734.7

Page 2

Short8_normalPool_Global 2

Project: EightmileLake Simulation Run: ExDamShort8PostBurnNormPoolReservoir: Existing Dam



Storage(AC-FT)

Elevation(FT)

Outflow(CFS)

01Jan2017 00:00 0.0 2208.6 4661.7 71.4

01Jan2017 00:05 0.0 2208.1 4661.7 71.4

01Jan2017 00:10 0.0 2207.6 4661.7 71.4

01Jan2017 00:15 0.0 2207.1 4661.7 71.4

01Jan2017 00:20 0.2 2206.7 4661.7 71.4

01Jan2017 00:25 1.1 2206.2 4661.7 71.3

01Jan2017 00:30 3.3 2205.7 4661.7 71.3

01Jan2017 00:35 7.2 2205.2 4661.7 71.3

01Jan2017 00:40 12.5 2204.8 4661.6 71.3

01Jan2017 00:45 19.1 2204.4 4661.6 71.3

01Jan2017 00:50 26.8 2204.1 4661.6 71.2

01Jan2017 00:55 34.3 2203.8 4661.6 71.2

01Jan2017 01:00 39.8 2203.6 4661.6 71.2

01Jan2017 01:05 42.7 2203.4 4661.6 71.2

01Jan2017 01:10 43.4 2203.2 4661.6 71.2

01Jan2017 01:15 42.8 2203.0 4661.6 71.2

01Jan2017 01:20 42.1 2202.8 4661.6 71.2

01Jan2017 01:25 43.6 2202.6 4661.6 71.2

01Jan2017 01:30 50.4 2202.4 4661.6 71.2

01Jan2017 01:35 66.0 2202.3 4661.6 71.2

01Jan2017 01:40 96.6 2202.4 4661.6 71.2

01Jan2017 01:45 155.0 2202.8 4661.6 71.2

01Jan2017 01:50 259.0 2203.7 4661.6 71.2

01Jan2017 01:55 443.6 2205.7 4661.7 71.3

01Jan2017 02:00 808.3 2209.5 4661.7 71.5

01Jan2017 02:05 1434.3 2216.7 4661.8 72.5

Page 1

Short8_NormalPool_timeTable 1


Storage(AC-FT)

Elevation(FT)

Outflow(CFS)

01Jan2017 02:10 2252.3 2228.9 4662.0 75.0

01Jan2017 02:15 3127.6 2246.9 4662.2 80.1

01Jan2017 02:20 3877.9 2270.4 4662.6 88.3

01Jan2017 02:25 4358.4 2298.1 4663.0 99.8

01Jan2017 02:30 4589.7 2328.2 4663.4 114.1

01Jan2017 02:35 4677.4 2359.3 4663.8 130.5

01Jan2017 02:40 4698.8 2390.6 4664.2 148.5

01Jan2017 02:45 4685.1 2421.8 4664.7 167.7

01Jan2017 02:50 4644.7 2452.7 4665.1 187.9

01Jan2017 02:55 4577.5 2483.1 4665.5 208.8

01Jan2017 03:00 4483.8 2512.8 4665.9 230.2

01Jan2017 03:05 4368.4 2541.6 4666.3 251.6

01Jan2017 03:10 4239.5 2569.5 4666.6 273.1

01Jan2017 03:15 4105.0 2596.3 4667.0 294.3

01Jan2017 03:20 3971.0 2621.9 4667.3 327.1

01Jan2017 03:25 3840.4 2646.4 4667.6 371.2

01Jan2017 03:30 3714.3 2669.7 4667.9 420.1

01Jan2017 03:35 3592.5 2691.8 4668.2 471.6

01Jan2017 03:40 3475.0 2712.7 4668.5 524.3

01Jan2017 03:45 3361.6 2732.5 4668.7 577.2

01Jan2017 03:50 3252.2 2751.1 4668.9 629.7

01Jan2017 03:55 3146.5 2768.6 4669.2 681.2

01Jan2017 04:00 3044.5 2785.1 4669.4 731.4

01Jan2017 04:05 2946.0 2800.5 4669.6 779.9

01Jan2017 04:10 2850.9 2814.9 4669.7 826.5

01Jan2017 04:15 2759.2 2828.4 4669.9 871.1

01Jan2017 04:20 2670.6 2841.0 4670.1 913.5

01Jan2017 04:25 2585.0 2852.6 4670.2 953.6

01Jan2017 04:30 2502.3 2863.4 4670.3 991.4

01Jan2017 04:35 2422.4 2873.5 4670.5 1026.8

01Jan2017 04:40 2345.2 2882.7 4670.6 1060.0

Page 2



Storage(AC-FT)

Elevation(FT)

Outflow(CFS)

01Jan2017 04:45 2270.6 2891.2 4670.7 1090.8

01Jan2017 04:50 2198.4 2899.0 4670.8 1119.3

01Jan2017 04:55 2128.4 2906.1 4670.9 1145.6

01Jan2017 05:00 2060.8 2912.5 4671.0 1169.7

01Jan2017 05:05 1995.4 2918.3 4671.0 1191.6

01Jan2017 05:10 1932.2 2923.6 4671.1 1211.5

01Jan2017 05:15 1871.2 2928.3 4671.1 1229.3

01Jan2017 05:20 1812.3 2932.4 4671.2 1245.2

01Jan2017 05:25 1755.3 2936.1 4671.2 1259.3

01Jan2017 05:30 1700.1 2939.3 4671.3 1271.5

01Jan2017 05:35 1646.8 2942.0 4671.3 1282.1

01Jan2017 05:40 1595.2 2944.3 4671.3 1291.0

01Jan2017 05:45 1545.3 2946.2 4671.4 1298.4

01Jan2017 05:50 1497.1 2947.7 4671.4 1304.3

01Jan2017 05:55 1450.5 2948.9 4671.4 1308.7

01Jan2017 06:00 1405.5 2949.7 4671.4 1311.9

01Jan2017 06:05 1361.9 2950.2 4671.4 1313.8

01Jan2017 06:10 1319.7 2950.4 4671.4 1314.5

01Jan2017 06:15 1279.0 2950.3 4671.4 1314.1

01Jan2017 06:20 1239.6 2949.9 4671.4 1312.7

01Jan2017 06:25 1201.5 2949.3 4671.4 1310.2

01Jan2017 06:30 1164.6 2948.4 4671.4 1306.9

01Jan2017 06:35 1128.9 2947.3 4671.4 1302.6

01Jan2017 06:40 1094.3 2946.0 4671.4 1297.6

01Jan2017 06:45 1060.9 2944.5 4671.3 1291.8

01Jan2017 06:50 1028.7 2942.8 4671.3 1285.3

01Jan2017 06:55 997.4 2941.0 4671.3 1278.1

01Jan2017 07:00 967.2 2939.0 4671.3 1270.4

01Jan2017 07:05 937.9 2936.8 4671.2 1262.0

01Jan2017 07:10 909.6 2934.5 4671.2 1253.2

01Jan2017 07:15 882.2 2932.1 4671.2 1243.9

Page 3



Storage(AC-FT)

Elevation(FT)

Outflow(CFS)

01Jan2017 07:20 855.7 2929.5 4671.2 1234.1

01Jan2017 07:25 830.1 2926.9 4671.1 1224.0

01Jan2017 07:30 805.2 2924.1 4671.1 1213.5

01Jan2017 07:35 781.2 2921.3 4671.1 1202.7

01Jan2017 07:40 757.9 2918.3 4671.0 1191.6

01Jan2017 07:45 735.4 2915.3 4671.0 1180.2

01Jan2017 07:50 713.5 2912.2 4670.9 1168.5

01Jan2017 07:55 692.4 2909.0 4670.9 1156.7

01Jan2017 08:00 671.9 2905.8 4670.9 1144.7

01Jan2017 08:05 652.1 2902.5 4670.8 1132.5

01Jan2017 08:10 632.9 2899.2 4670.8 1120.2

01Jan2017 08:15 614.3 2895.8 4670.7 1107.8

01Jan2017 08:20 596.3 2892.4 4670.7 1095.3

01Jan2017 08:25 578.8 2888.9 4670.7 1082.7

01Jan2017 08:30 561.9 2885.5 4670.6 1070.0

01Jan2017 08:35 545.5 2881.9 4670.6 1057.3

01Jan2017 08:40 529.6 2878.4 4670.5 1044.6

01Jan2017 08:45 514.3 2874.9 4670.5 1031.9

01Jan2017 08:50 499.3 2871.3 4670.4 1019.1

01Jan2017 08:55 484.9 2867.7 4670.4 1006.4

01Jan2017 09:00 470.9 2864.1 4670.4 993.7

01Jan2017 09:05 457.2 2860.5 4670.3 981.0

01Jan2017 09:10 444.0 2856.9 4670.3 968.4

01Jan2017 09:15 431.2 2853.3 4670.2 955.8

01Jan2017 09:20 418.8 2849.7 4670.2 943.3

01Jan2017 09:25 406.9 2846.1 4670.1 930.9

01Jan2017 09:30 395.3 2842.4 4670.1 918.5

01Jan2017 09:35 384.0 2838.8 4670.0 906.3

01Jan2017 09:40 373.1 2835.3 4670.0 894.1

01Jan2017 09:45 362.5 2831.7 4669.9 882.0

01Jan2017 09:50 352.3 2828.1 4669.9 870.1

Page 4



Storage(AC-FT)

Elevation(FT)

Outflow(CFS)

01Jan2017 09:55 342.3 2824.5 4669.9 858.2

01Jan2017 10:00 332.7 2821.0 4669.8 846.5

01Jan2017 10:05 323.3 2817.5 4669.8 834.8

01Jan2017 10:10 314.3 2813.9 4669.7 823.3

01Jan2017 10:15 305.5 2810.5 4669.7 811.9

01Jan2017 10:20 296.9 2807.0 4669.6 800.7

01Jan2017 10:25 288.7 2803.5 4669.6 789.6

01Jan2017 10:30 280.6 2800.1 4669.6 778.6

01Jan2017 10:35 272.8 2796.7 4669.5 767.7

01Jan2017 10:40 265.3 2793.3 4669.5 757.0

01Jan2017 10:45 257.9 2789.9 4669.4 746.4

01Jan2017 10:50 250.8 2786.5 4669.4 735.9

01Jan2017 10:55 243.9 2783.2 4669.3 725.6

01Jan2017 11:00 237.2 2779.9 4669.3 715.5

01Jan2017 11:05 230.7 2776.6 4669.3 705.4

01Jan2017 11:10 224.4 2773.4 4669.2 695.5

01Jan2017 11:15 218.2 2770.1 4669.2 685.8

01Jan2017 11:20 212.3 2766.9 4669.1 676.1

01Jan2017 11:25 206.5 2763.7 4669.1 666.7

01Jan2017 11:30 200.8 2760.6 4669.1 657.3

01Jan2017 11:35 195.3 2757.4 4669.0 648.2

01Jan2017 11:40 190.0 2754.3 4669.0 639.1

01Jan2017 11:45 184.9 2751.3 4668.9 630.2

01Jan2017 11:50 179.9 2748.2 4668.9 621.4

01Jan2017 11:55 175.0 2745.2 4668.9 612.7

01Jan2017 12:00 170.3 2742.2 4668.8 604.2

Page 5


E l e v ( f t )

4,660

4,662

4,664

4,666

4,668

4,670

4,672

00:00 02:00 04:00 06:00 08:00 10:00 12:00

01Jan2017

F l o w ( c f s )

0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

4,500

5,000

Existing Dam

Run:ExDamShort8PostBurnNormPool Element:Existing Dam Result:Pool Elevation Run:ExDamShort8PostBurnNormPool Element:Existing Dam Result:Outflow

Run:ExDamShort8PostBurnNormPool Element:Existing Dam Result:Combined Inflow Run:ExDamShort8PostBurnNormPool Element:Existing Dam-OUTLET-1 Result:Outlet 1

Run:ExDamShort8PostBurnNormPool Element:Existing Dam-SPILL-1 Result:Spillway 1 Run:ExDamShort8PostBurnNormPool Element:Existing Dam-DAMTOP-1 Result:Dam Top 1

Short8_NormalPool_Graph

Project: EightmileLake Simulation Run: ExDamShort3PostBurnNormPool


HydrologicElement

Drainage Area(MI2)

Peak Discharge(CFS)


W290A 0.59 193.9 01Jan2017, 02:45 56.7

W320 0.338 122.5 01Jan2017, 02:40 29.9

W290B 0.07 40.6 01Jan2017, 02:25 9.7

J49 0.998 356.0 01Jan2017, 02:40 96.4

W340 0.798 383.8 01Jan2017, 02:25 85.6

J30 0.798 383.8 01Jan2017, 02:25 85.6

R10 0.798 383.8 01Jan2017, 02:30 85.6

R130 1.796 737.9 01Jan2017, 02:40 181.8

W300 0.635 148.3 01Jan2017, 02:50 43.8

W310 0.3699 157.2 01Jan2017, 02:30 34.9

J63 2.8009 1040.9 01Jan2017, 02:40 260.5

R110 2.8009 1040.2 01Jan2017, 02:45 260.4

W190A 0.18 67.6 01Jan2017, 02:40 17.6

W190B 0.04 23.9 01Jan2017, 02:20 3.8

J52 3.0209 1128.9 01Jan2017, 02:45 281.8

R80 3.0209 1128.9 01Jan2017, 02:45 281.6

W180A 0.96 235.0 01Jan2017, 02:50 83.6

W200 0.813 264.1 01Jan2017, 02:40 68.9

W180B 0.02 21.5 01Jan2017, 02:10 2.4

J56 4.8139 1642.5 01Jan2017, 02:45 436.6

R30 4.8139 1641.1 01Jan2017, 02:45 436.5

W270 0.567 243.2 01Jan2017, 02:30 55.7

W250 0.453 70.2 01Jan2017, 02:55 25.9

Existing Dam 5.8339 271.2 01Jan2017, 08:05 196.7

Short3_normalPool_Global

Project: EightmileLake Simulation Run: ExDamShort3PostBurnNormPoolReservoir: Existing Dam



Storage(AC-FT)

Elevation(FT)

Outflow(CFS)

01Jan2017 00:00 0.0 2208.6 4661.7 71.4

01Jan2017 00:05 0.0 2208.1 4661.7 71.4

01Jan2017 00:10 0.0 2207.6 4661.7 71.4

01Jan2017 00:15 0.0 2207.1 4661.7 71.4

01Jan2017 00:20 0.0 2206.7 4661.7 71.4

01Jan2017 00:25 0.1 2206.2 4661.7 71.3

01Jan2017 00:30 0.3 2205.7 4661.7 71.3

01Jan2017 00:35 0.6 2205.2 4661.7 71.3

01Jan2017 00:40 0.8 2204.7 4661.6 71.3

01Jan2017 00:45 1.2 2204.2 4661.6 71.3

01Jan2017 00:50 1.8 2203.7 4661.6 71.2

01Jan2017 00:55 2.5 2203.3 4661.6 71.2

01Jan2017 01:00 3.2 2202.8 4661.6 71.2

01Jan2017 01:05 3.8 2202.3 4661.6 71.2

01Jan2017 01:10 4.4 2201.9 4661.6 71.1

01Jan2017 01:15 4.7 2201.4 4661.6 71.1

01Jan2017 01:20 4.9 2200.9 4661.6 71.1

01Jan2017 01:25 5.4 2200.5 4661.6 71.1

01Jan2017 01:30 6.8 2200.0 4661.6 71.1

01Jan2017 01:35 9.5 2199.6 4661.6 71.0

01Jan2017 01:40 14.7 2199.2 4661.6 71.0

01Jan2017 01:45 24.8 2198.9 4661.6 71.0

01Jan2017 01:50 44.4 2198.6 4661.6 71.0

01Jan2017 01:55 87.0 2198.6 4661.6 71.0

01Jan2017 02:00 197.8 2199.1 4661.6 71.0

01Jan2017 02:05 417.0 2200.7 4661.6 71.1

Page 1



Storage(AC-FT)

Elevation(FT)

Outflow(CFS)

01Jan2017 02:10 721.2 2204.1 4661.6 71.2

01Jan2017 02:15 1053.5 2209.7 4661.7 71.5

01Jan2017 02:20 1392.6 2217.7 4661.8 72.6

01Jan2017 02:25 1671.8 2227.7 4662.0 74.7

01Jan2017 02:30 1834.3 2239.3 4662.1 77.8

01Jan2017 02:35 1910.1 2251.6 4662.3 81.6

01Jan2017 02:40 1940.1 2264.3 4662.5 86.0

01Jan2017 02:45 1948.6 2277.1 4662.7 90.9

01Jan2017 02:50 1941.4 2289.8 4662.9 96.1

01Jan2017 02:55 1919.9 2302.4 4663.0 101.7

01Jan2017 03:00 1884.5 2314.8 4663.2 107.5

01Jan2017 03:05 1838.3 2326.9 4663.4 113.4

01Jan2017 03:10 1785.1 2338.5 4663.5 119.4

01Jan2017 03:15 1728.9 2349.8 4663.7 125.3

01Jan2017 03:20 1672.3 2360.6 4663.8 131.2

01Jan2017 03:25 1616.9 2371.0 4664.0 137.1

01Jan2017 03:30 1563.3 2381.0 4664.1 142.8

01Jan2017 03:35 1511.5 2390.6 4664.2 148.5

01Jan2017 03:40 1461.7 2399.8 4664.4 154.0

01Jan2017 03:45 1413.5 2408.6 4664.5 159.4

01Jan2017 03:50 1367.1 2417.1 4664.6 164.7

01Jan2017 03:55 1322.3 2425.2 4664.7 169.9

01Jan2017 04:00 1279.1 2433.0 4664.8 174.9

01Jan2017 04:05 1237.3 2440.4 4664.9 179.7

01Jan2017 04:10 1197.1 2447.5 4665.0 184.5

01Jan2017 04:15 1158.2 2454.4 4665.1 189.0

01Jan2017 04:20 1120.7 2460.9 4665.2 193.4

01Jan2017 04:25 1084.4 2467.1 4665.3 197.7

01Jan2017 04:30 1049.4 2473.1 4665.3 201.8

01Jan2017 04:35 1015.6 2478.8 4665.4 205.8

01Jan2017 04:40 982.9 2484.3 4665.5 209.6

Page 2



Storage(AC-FT)

Elevation(FT)

Outflow(CFS)

01Jan2017 04:45 951.4 2489.5 4665.6 213.3

01Jan2017 04:50 920.8 2494.4 4665.6 216.9

01Jan2017 04:55 891.1 2499.2 4665.7 220.2

01Jan2017 05:00 862.5 2503.7 4665.8 223.5

01Jan2017 05:05 834.9 2508.0 4665.8 226.6

01Jan2017 05:10 808.2 2512.1 4665.9 229.6

01Jan2017 05:15 782.3 2515.9 4665.9 232.4

01Jan2017 05:20 757.3 2519.6 4666.0 235.2

01Jan2017 05:25 733.2 2523.1 4666.0 237.8

01Jan2017 05:30 709.9 2526.5 4666.1 240.2

01Jan2017 05:35 687.4 2529.6 4666.1 242.6

01Jan2017 05:40 665.6 2532.6 4666.1 244.8

01Jan2017 05:45 644.5 2535.4 4666.2 246.9

01Jan2017 05:50 624.2 2538.1 4666.2 248.9

01Jan2017 05:55 604.6 2540.6 4666.2 250.8

01Jan2017 06:00 585.6 2542.9 4666.3 252.6

01Jan2017 06:05 567.2 2545.2 4666.3 254.3

01Jan2017 06:10 549.5 2547.3 4666.3 255.9

01Jan2017 06:15 532.3 2549.2 4666.3 257.4

01Jan2017 06:20 515.7 2551.0 4666.4 258.8

01Jan2017 06:25 499.7 2552.8 4666.4 260.1

01Jan2017 06:30 484.1 2554.3 4666.4 261.3

01Jan2017 06:35 469.1 2555.8 4666.4 262.5

01Jan2017 06:40 454.6 2557.2 4666.5 263.5

01Jan2017 06:45 440.6 2558.5 4666.5 264.5

01Jan2017 06:50 427.0 2559.6 4666.5 265.4

01Jan2017 06:55 413.9 2560.7 4666.5 266.2

01Jan2017 07:00 401.2 2561.7 4666.5 267.0

01Jan2017 07:05 388.9 2562.5 4666.5 267.7

01Jan2017 07:10 377.1 2563.3 4666.5 268.3

01Jan2017 07:15 365.6 2564.0 4666.5 268.8

Page 3



Storage(AC-FT)

Elevation(FT)

Outflow(CFS)

01Jan2017 07:20 354.5 2564.7 4666.6 269.3

01Jan2017 07:25 343.7 2565.2 4666.6 269.7

01Jan2017 07:30 333.3 2565.7 4666.6 270.1

01Jan2017 07:35 323.2 2566.1 4666.6 270.4

01Jan2017 07:40 313.5 2566.4 4666.6 270.7

01Jan2017 07:45 304.1 2566.7 4666.6 270.9

01Jan2017 07:50 294.9 2566.9 4666.6 271.0

01Jan2017 07:55 286.1 2567.0 4666.6 271.1

01Jan2017 08:00 277.5 2567.1 4666.6 271.2

01Jan2017 08:05 269.3 2567.1 4666.6 271.2

01Jan2017 08:10 261.2 2567.1 4666.6 271.2

01Jan2017 08:15 253.5 2567.0 4666.6 271.1

01Jan2017 08:20 246.0 2566.8 4666.6 271.0

01Jan2017 08:25 238.7 2566.6 4666.6 270.8

01Jan2017 08:30 231.6 2566.4 4666.6 270.6

01Jan2017 08:35 224.8 2566.1 4666.6 270.4

01Jan2017 08:40 218.2 2565.7 4666.6 270.2

01Jan2017 08:45 211.8 2565.4 4666.6 269.9

01Jan2017 08:50 205.6 2564.9 4666.6 269.5

01Jan2017 08:55 199.6 2564.5 4666.5 269.2

01Jan2017 09:00 193.7 2564.0 4666.5 268.8

01Jan2017 09:05 188.1 2563.5 4666.5 268.4

01Jan2017 09:10 182.6 2562.9 4666.5 267.9

01Jan2017 09:15 177.2 2562.3 4666.5 267.5

01Jan2017 09:20 172.1 2561.6 4666.5 267.0

01Jan2017 09:25 167.1 2561.0 4666.5 266.5

01Jan2017 09:30 162.3 2560.3 4666.5 265.9

01Jan2017 09:35 157.6 2559.5 4666.5 265.3

01Jan2017 09:40 153.1 2558.8 4666.5 264.8

01Jan2017 09:45 148.7 2558.0 4666.5 264.2

01Jan2017 09:50 144.4 2557.2 4666.5 263.5

Page 4



Storage(AC-FT)

Elevation(FT)

Outflow(CFS)

01Jan2017 09:55 140.3 2556.4 4666.4 262.9

01Jan2017 10:00 136.3 2555.5 4666.4 262.2

01Jan2017 10:05 132.5 2554.6 4666.4 261.6

01Jan2017 10:10 128.7 2553.7 4666.4 260.9

01Jan2017 10:15 125.1 2552.8 4666.4 260.2

01Jan2017 10:20 121.5 2551.9 4666.4 259.4

01Jan2017 10:25 118.1 2550.9 4666.4 258.7

01Jan2017 10:30 114.8 2549.9 4666.4 258.0

01Jan2017 10:35 111.6 2548.9 4666.3 257.2

01Jan2017 10:40 108.4 2547.9 4666.3 256.4

01Jan2017 10:45 105.4 2546.9 4666.3 255.6

01Jan2017 10:50 102.5 2545.9 4666.3 254.8

01Jan2017 10:55 99.6 2544.8 4666.3 254.0

01Jan2017 11:00 96.8 2543.7 4666.3 253.2

01Jan2017 11:05 94.1 2542.6 4666.3 252.4

01Jan2017 11:10 91.5 2541.6 4666.2 251.6

01Jan2017 11:15 89.0 2540.4 4666.2 250.7

01Jan2017 11:20 86.5 2539.3 4666.2 249.9

01Jan2017 11:25 84.2 2538.2 4666.2 249.0

01Jan2017 11:30 81.8 2537.1 4666.2 248.2

01Jan2017 11:35 79.6 2535.9 4666.2 247.3

01Jan2017 11:40 77.4 2534.7 4666.2 246.4

01Jan2017 11:45 75.3 2533.6 4666.1 245.6

01Jan2017 11:50 73.2 2532.4 4666.1 244.7

01Jan2017 11:55 71.2 2531.2 4666.1 243.8

01Jan2017 12:00 69.3 2530.0 4666.1 242.9

Page 5


E l e v ( f t )

4,661

4,662

4,663

4,664

4,665

4,666

4,667

00:00 02:00 04:00 06:00 08:00 10:00 12:00

01Jan2017

F l o w ( c f s )

0

200

400

600

800

1,000

1,200

1,400

1,600

1,800

2,000

Existing Dam

Run:ExDamShort3PostBurnNormPool Element:Existing Dam Result:Pool Elevation Run:ExDamShort3PostBurnNormPool Element:Existing Dam-DAMTOP-1 Result:Dam Top 1

Run:ExDamShort3PostBurnNormPool Element:Existing Dam-SPILL-1 Result:Spillway 1 Run:ExDamShort3PostBurnNormPool Element:Existing Dam-OUTLET-1 Result:Outlet 1

Run:ExDamShort3PostBurnNormPool Element:Existing Dam Result:Combined Inflow Run:ExDamShort3PostBurnNormPool Element:Existing Dam Result:Outflow

Short3_NormalPool_Graph

Project: EightmileLake Simulation Run: ExInt8NormPoolBurn


HydrologicElement

Drainage Area(MI2)

Peak Discharge(CFS)


W290A 0.59 599.6 01Jan2017, 14:45 477.6

W320 0.338 377.2 01Jan2017, 14:15 268.9

W290B 0.07 81.4 01Jan2017, 14:15 59.4

J49 0.998 1056.0 01Jan2017, 14:15 805.9

W340 0.798 940.9 01Jan2017, 14:15 653.2

J30 0.798 940.9 01Jan2017, 14:15 653.2

R10 0.798 939.8 01Jan2017, 14:15 653.2

R130 1.796 1987.2 01Jan2017, 14:30 1459.2

W300 0.635 628.9 01Jan2017, 15:00 486.6

W310 0.3699 434.9 01Jan2017, 14:15 297.5

J63 2.8009 3045.4 01Jan2017, 14:15 2243.3

R110 2.8009 3043.3 01Jan2017, 14:30 2243.4

W190A 0.18 195.2 01Jan2017, 14:15 145.7

W190B 0.04 55.6 01Jan2017, 14:00 34.1

J52 3.0209 3290.0 01Jan2017, 14:30 2423.2

R80 3.0209 3289.3 01Jan2017, 14:30 2423.4

W180A 0.96 871.8 01Jan2017, 15:30 769.5

W200 0.813 885.6 01Jan2017, 14:15 663.1

W180B 0.02 32.4 01Jan2017, 13:45 17.7

J56 4.8139 5053.3 01Jan2017, 14:30 3873.6

R30 4.8139 5051.6 01Jan2017, 14:30 3873.6

W270 0.567 654.5 01Jan2017, 14:15 454.6

W250 0.453 383.5 01Jan2017, 15:30 330.6

Existing Dam 5.8339 4678.1 01Jan2017, 17:00 3570.0

Int8_NormalPool_Global

Project: EightmileLake Simulation Run: ExInt8NormPoolBurnReservoir: Existing Dam



Storage(AC-FT)

Elevation(FT)

Outflow(CFS)

01Jan2017 00:00 0.0 1442.1 4648.6 0.0

01Jan2017 00:15 0.0 1442.1 4648.6 0.0

01Jan2017 00:30 0.0 1442.1 4648.6 0.0

01Jan2017 00:45 0.0 1442.1 4648.6 0.0

01Jan2017 01:00 0.1 1442.1 4648.6 0.0

01Jan2017 01:15 0.3 1442.1 4648.6 0.0

01Jan2017 01:30 0.7 1442.1 4648.6 0.0

01Jan2017 01:45 1.7 1442.1 4648.7 0.0

01Jan2017 02:00 5.2 1442.2 4648.7 0.0

01Jan2017 02:15 14.1 1442.4 4648.7 0.0

01Jan2017 02:30 30.9 1442.9 4648.7 0.0

01Jan2017 02:45 58.1 1443.8 4648.7 0.0

01Jan2017 03:00 98.4 1445.4 4648.7 0.0

01Jan2017 03:15 152.7 1448.0 4648.8 0.1

01Jan2017 03:30 221.3 1451.9 4648.8 0.2

01Jan2017 03:45 304.2 1457.3 4649.0 0.6

01Jan2017 04:00 397.5 1464.5 4649.1 1.1

01Jan2017 04:15 498.7 1473.7 4649.3 2.2

01Jan2017 04:30 608.3 1485.1 4649.5 3.7

01Jan2017 04:45 726.5 1498.8 4649.8 6.0

01Jan2017 05:00 852.4 1514.9 4650.1 9.0

01Jan2017 05:15 985.4 1533.7 4650.5 12.8

01Jan2017 05:30 1124.4 1555.2 4650.9 17.3

01Jan2017 05:45 1272.2 1579.5 4651.4 22.5

01Jan2017 06:00 1437.0 1607.0 4651.9 28.4

01Jan2017 06:15 1624.9 1638.0 4652.5 32.9

Page 1

Int8_NormalPool_TimeTablel 1


Storage(AC-FT)

Elevation(FT)

Outflow(CFS)

01Jan2017 06:30 1845.1 1673.1 4653.1 36.9

01Jan2017 06:45 2111.4 1713.2 4653.8 40.9

01Jan2017 07:00 2383.7 1758.7 4654.6 45.0

01Jan2017 07:15 2598.9 1809.2 4655.5 49.0

01Jan2017 07:30 2747.8 1863.4 4656.4 52.9

01Jan2017 07:45 2842.4 1920.0 4657.3 56.5

01Jan2017 08:00 2894.9 1978.1 4658.2 60.0

01Jan2017 08:15 2915.7 2036.9 4659.2 63.2

01Jan2017 08:30 2909.9 2095.7 4660.0 66.2

01Jan2017 08:45 2880.3 2154.1 4660.9 69.0

01Jan2017 09:00 2833.1 2211.7 4661.7 71.7

01Jan2017 09:15 2771.6 2268.0 4662.5 87.3

01Jan2017 09:30 2693.1 2322.4 4663.3 111.2

01Jan2017 09:45 2601.6 2374.5 4664.0 139.1

01Jan2017 10:00 2507.7 2424.1 4664.7 169.2

01Jan2017 10:15 2424.0 2471.2 4665.3 200.5

01Jan2017 10:30 2354.2 2516.1 4665.9 232.6

01Jan2017 10:45 2298.0 2559.0 4666.5 265.0

01Jan2017 11:00 2258.4 2600.3 4667.0 297.7

01Jan2017 11:15 2244.1 2640.1 4667.5 358.9

01Jan2017 11:30 2290.2 2678.7 4668.0 440.4

01Jan2017 11:45 2416.1 2717.2 4668.5 536.0

01Jan2017 12:00 2601.6 2756.8 4669.0 646.4

01Jan2017 12:15 2825.2 2798.2 4669.5 772.8

01Jan2017 12:30 3069.4 2841.7 4670.1 916.0

01Jan2017 12:45 3318.2 2887.1 4670.6 1076.0

01Jan2017 13:00 3583.4 2934.3 4671.2 1252.5

01Jan2017 13:15 3927.4 2984.0 4671.8 1448.1

01Jan2017 13:30 4594.1 3039.7 4672.5 1678.7

01Jan2017 13:45 5369.4 3105.0 4673.3 1962.4

01Jan2017 14:00 5836.3 3176.9 4674.1 2289.7

Page 2



Storage(AC-FT)

Elevation(FT)

Outflow(CFS)

01Jan2017 14:15 6033.7 3248.6 4675.0 2631.2

01Jan2017 14:30 6068.1 3315.8 4675.8 2962.9

01Jan2017 14:45 6053.4 3376.6 4676.5 3272.1

01Jan2017 15:00 6022.9 3430.8 4677.1 3554.6

01Jan2017 15:15 5973.8 3478.6 4677.6 3809.0

01Jan2017 15:30 5904.4 3520.3 4678.1 4034.2

01Jan2017 15:45 5811.1 3555.9 4678.5 4229.6

01Jan2017 16:00 5671.6 3585.5 4678.8 4393.5

01Jan2017 16:15 5476.0 3608.5 4679.1 4522.7

01Jan2017 16:30 5221.5 3624.6 4679.3 4613.7

01Jan2017 16:45 4929.1 3633.6 4679.4 4664.8

01Jan2017 17:00 4640.5 3636.0 4679.4 4678.1

01Jan2017 17:15 4369.5 3632.6 4679.4 4658.9

01Jan2017 17:30 4121.8 3624.5 4679.3 4613.2

01Jan2017 17:45 3893.0 3612.7 4679.1 4546.4

01Jan2017 18:00 3679.7 3597.9 4679.0 4463.0

01Jan2017 18:15 3440.8 3580.2 4678.8 4364.4

01Jan2017 18:30 3162.0 3559.5 4678.6 4249.1

01Jan2017 18:45 2885.6 3535.5 4678.3 4117.2

01Jan2017 19:00 2629.1 3508.9 4678.0 3972.2

01Jan2017 19:15 2395.9 3480.3 4677.7 3818.1

01Jan2017 19:30 2184.5 3450.4 4677.3 3658.5

01Jan2017 19:45 1992.7 3419.7 4677.0 3496.3

01Jan2017 20:00 1818.7 3388.5 4676.6 3333.8

01Jan2017 20:15 1660.8 3357.3 4676.2 3173.0

01Jan2017 20:30 1517.4 3326.2 4675.9 3015.2

01Jan2017 20:45 1387.2 3295.5 4675.5 2861.7

01Jan2017 21:00 1268.9 3265.4 4675.2 2713.0

01Jan2017 21:15 1161.3 3236.0 4674.8 2570.0

01Jan2017 21:30 1063.4 3207.3 4674.5 2432.8

01Jan2017 21:45 974.2 3179.4 4674.2 2301.7

Page 3



Storage(AC-FT)

Elevation(FT)

Outflow(CFS)

01Jan2017 22:00 892.8 3152.5 4673.8 2176.8

01Jan2017 22:15 818.5 3126.4 4673.5 2058.1

01Jan2017 22:30 750.6 3101.3 4673.2 1945.5

01Jan2017 22:45 688.4 3077.0 4672.9 1838.9

01Jan2017 23:00 631.6 3053.7 4672.7 1738.1

01Jan2017 23:15 579.6 3031.3 4672.4 1643.0

01Jan2017 23:30 532.0 3009.8 4672.1 1553.2

01Jan2017 23:45 488.4 2989.1 4671.9 1468.6

02Jan2017 00:00 448.3 2969.2 4671.6 1388.9

02Jan2017 00:15 411.1 2950.2 4671.4 1313.8

02Jan2017 00:30 376.8 2931.9 4671.2 1243.2

02Jan2017 00:45 345.1 2914.4 4671.0 1176.7

02Jan2017 01:00 316.6 2897.5 4670.8 1114.2

02Jan2017 01:15 290.7 2881.4 4670.6 1055.4

02Jan2017 01:30 267.0 2865.9 4670.4 1000.1

02Jan2017 01:45 245.1 2851.1 4670.2 948.3

02Jan2017 02:00 225.0 2836.9 4670.0 899.6

02Jan2017 02:15 206.6 2823.2 4669.8 853.8

02Jan2017 02:30 189.6 2810.1 4669.7 810.8

02Jan2017 02:45 173.9 2797.5 4669.5 770.5

02Jan2017 03:00 159.0 2785.4 4669.4 732.5

02Jan2017 03:15 145.9 2773.8 4669.2 696.9

02Jan2017 03:30 133.9 2762.7 4669.1 663.5

02Jan2017 03:45 123.0 2751.9 4669.0 632.1

02Jan2017 04:00 112.9 2741.6 4668.8 602.6

02Jan2017 04:15 103.6 2731.7 4668.7 575.0

02Jan2017 04:30 95.0 2722.1 4668.6 549.1

02Jan2017 04:45 87.1 2712.9 4668.5 524.7

02Jan2017 05:00 79.7 2704.0 4668.3 501.9

02Jan2017 05:15 72.9 2695.5 4668.2 480.5

02Jan2017 05:30 66.7 2687.2 4668.1 460.4

Page 4



Storage(AC-FT)

Elevation(FT)

Outflow(CFS)

02Jan2017 05:45 61.0 2679.2 4668.0 441.5

02Jan2017 06:00 55.9 2671.4 4667.9 423.9

02Jan2017 06:15 51.3 2664.0 4667.8 407.4

02Jan2017 06:30 47.1 2656.7 4667.7 392.0

02Jan2017 06:45 43.4 2649.7 4667.7 377.7

02Jan2017 07:00 39.9 2642.9 4667.6 364.3

02Jan2017 07:15 36.7 2636.3 4667.5 351.9

02Jan2017 07:30 33.7 2629.9 4667.4 340.4

02Jan2017 07:45 31.1 2623.6 4667.3 329.8

02Jan2017 08:00 28.7 2617.5 4667.2 320.2

02Jan2017 08:15 26.6 2611.6 4667.2 311.5

02Jan2017 08:30 24.5 2605.7 4667.1 303.8

02Jan2017 08:45 22.6 2600.0 4667.0 297.4

02Jan2017 09:00 20.7 2594.4 4666.9 292.7

02Jan2017 09:15 19.0 2588.8 4666.9 288.3

02Jan2017 09:30 17.4 2583.2 4666.8 283.9

02Jan2017 09:45 15.9 2577.8 4666.7 279.6

02Jan2017 10:00 14.5 2572.3 4666.7 275.3

02Jan2017 10:15 13.0 2567.0 4666.6 271.1

02Jan2017 10:30 11.3 2561.7 4666.5 267.0

02Jan2017 10:45 10.0 2556.4 4666.4 262.9

02Jan2017 11:00 8.8 2551.2 4666.4 258.9

02Jan2017 11:15 7.9 2546.1 4666.3 255.0

02Jan2017 11:30 7.0 2541.0 4666.2 251.2

02Jan2017 11:45 6.1 2536.0 4666.2 247.4

02Jan2017 12:00 5.3 2531.0 4666.1 243.6

Page 5


E l e v ( f t )

4,645

4,650

4,655

4,660

4,665

4,670

4,675

4,680

00:00 06:00 12:00 18:00 00:00 06:00 12:00

01Jan2017 02Jan2017

F l o w ( c f s )

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

Existing Dam

Run:ExInt8NormPoolBurn Element:Existing Dam Result:Pool Elevation Run:ExInt8NormPoolBurn Element:Existing Dam Result:Combined Inflow

Run:ExInt8NormPoolBurn Element:Existing Dam Result:Outflow Run:ExInt8NormPoolBurn Element:Existing Dam-OUTLET-1 Result:Outlet 1

Run:ExInt8NormPoolBurn Element:Existing Dam-SPILL-1 Result:Spillway 1 Run:ExInt8NormPoolBurn Element:Existing Dam-DAMTOP-1 Result:Dam Top 1

Int8_NormalPool_Graph

Project: EightmileLake Simulation Run: ExDamInt10yrPostBurnNormPool

Start of Run: 01Jan2017, 00:00 Basin Model: ExDamPostBurnNorEnd of Run: 02Jan2017, 12:00 Meteorologic Model: Int10yrSnowCompute Time: 12Apr2018, 11:28:57 Control Specifications:Intermediate

HydrologicElement

Drainage Area(MI2)

Peak Discharge(CFS)


W290A 0.59 179.7 01Jan2017, 15:00 129.1

W320 0.338 111.1 01Jan2017, 14:15 69.2

W290B 0.07 26.1 01Jan2017, 14:15 17.4

J49 0.998 315.8 01Jan2017, 14:45 215.7

W340 0.798 288.2 01Jan2017, 14:15 180.0

J30 0.798 288.2 01Jan2017, 14:15 180.0

R10 0.798 287.4 01Jan2017, 14:15 180.0

R130 1.796 601.7 01Jan2017, 14:30 395.8

W300 0.635 175.2 01Jan2017, 15:30 115.1

W310 0.3699 130.6 01Jan2017, 14:15 78.7

J63 2.8009 902.6 01Jan2017, 14:30 589.5

R110 2.8009 901.6 01Jan2017, 14:45 589.6

W190A 0.18 58.4 01Jan2017, 14:30 39.4

W190B 0.04 18.1 01Jan2017, 14:00 10.1

J52 3.0209 977.0 01Jan2017, 14:30 639.1

R80 3.0209 976.6 01Jan2017, 14:45 639.1

W180A 0.96 256.6 01Jan2017, 15:45 204.7

W200 0.813 271.9 01Jan2017, 14:30 177.4

W180B 0.02 10.9 01Jan2017, 13:45 5.6

J56 4.8139 1506.6 01Jan2017, 14:45 1026.8

R30 4.8139 1506.3 01Jan2017, 14:45 1026.8

W270 0.567 194.4 01Jan2017, 14:15 120.9

W250 0.453 97.4 01Jan2017, 16:00 72.1

Existing Dam 5.8339 959.4 01Jan2017, 18:30 976.9

Int10yr_NormalPool_Global

Project: EightmileLake Simulation Run: ExDamInt10yrPostBurnNormPoolReservoir: Existing Dam

Start of Run: 01Jan2017, 00:00 Basin Model: ExDamPostBurnNorEnd of Run: 02Jan2017, 12:00 Meteorologic Model: Int10yrSnowCompute Time: 12Apr2018, 11:28:57 Control Specifications:Intermediate


Storage(AC-FT)

Elevation(FT)

Outflow(CFS)

01Jan2017 00:00 0.0 2208.6 4661.7 71.4

01Jan2017 00:15 0.0 2207.1 4661.7 71.4

01Jan2017 00:30 0.0 2205.7 4661.7 71.3

01Jan2017 00:45 0.0 2204.2 4661.6 71.2

01Jan2017 01:00 0.0 2202.7 4661.6 71.2

01Jan2017 01:15 0.0 2201.3 4661.6 71.1

01Jan2017 01:30 0.0 2199.8 4661.6 71.1

01Jan2017 01:45 0.0 2198.3 4661.6 71.0

01Jan2017 02:00 0.1 2196.9 4661.5 70.9

01Jan2017 02:15 0.1 2195.4 4661.5 70.9

01Jan2017 02:30 0.3 2193.9 4661.5 70.8

01Jan2017 02:45 0.4 2192.5 4661.5 70.7

01Jan2017 03:00 0.7 2191.0 4661.4 70.7

01Jan2017 03:15 1.1 2189.6 4661.4 70.6

01Jan2017 03:30 2.0 2188.2 4661.4 70.5

01Jan2017 03:45 4.0 2186.8 4661.4 70.5

01Jan2017 04:00 8.1 2185.4 4661.4 70.4

01Jan2017 04:15 14.3 2184.2 4661.3 70.4

01Jan2017 04:30 23.1 2183.1 4661.3 70.3

01Jan2017 04:45 34.7 2182.3 4661.3 70.3

01Jan2017 05:00 49.0 2181.7 4661.3 70.2

01Jan2017 05:15 67.3 2181.5 4661.3 70.2

01Jan2017 05:30 89.9 2181.6 4661.3 70.2

01Jan2017 05:45 115.6 2182.3 4661.3 70.3

01Jan2017 06:00 145.2 2183.5 4661.3 70.3

01Jan2017 06:15 182.7 2185.5 4661.4 70.4

Page 1

Int10yr_NormalPool_TimeTablel 1


Storage(AC-FT)

Elevation(FT)

Outflow(CFS)

01Jan2017 06:30 231.0 2188.3 4661.4 70.5

01Jan2017 06:45 291.8 2192.2 4661.5 70.7

01Jan2017 07:00 358.7 2197.5 4661.5 71.0

01Jan2017 07:15 420.6 2204.1 4661.6 71.2

01Jan2017 07:30 471.1 2211.8 4661.7 71.8

01Jan2017 07:45 507.7 2220.4 4661.9 73.2

01Jan2017 08:00 535.1 2229.7 4662.0 75.2

01Jan2017 08:15 555.9 2239.4 4662.1 77.8

01Jan2017 08:30 571.4 2249.4 4662.3 80.8

01Jan2017 08:45 582.0 2259.6 4662.4 84.3

01Jan2017 09:00 585.0 2269.8 4662.6 88.1

01Jan2017 09:15 582.2 2280.0 4662.7 92.1

01Jan2017 09:30 574.8 2290.0 4662.9 96.2

01Jan2017 09:45 563.5 2299.8 4663.0 100.5

01Jan2017 10:00 551.6 2309.2 4663.1 104.8

01Jan2017 10:15 540.5 2318.2 4663.2 109.2

01Jan2017 10:30 530.9 2327.0 4663.4 113.5

01Jan2017 10:45 525.6 2335.5 4663.5 117.8

01Jan2017 11:00 525.7 2343.9 4663.6 122.2

01Jan2017 11:15 531.6 2352.3 4663.7 126.7

01Jan2017 11:30 552.0 2360.8 4663.8 131.3

01Jan2017 11:45 594.1 2369.9 4664.0 136.4

01Jan2017 12:00 653.4 2379.9 4664.1 142.2

01Jan2017 12:15 723.7 2391.1 4664.2 148.8

01Jan2017 12:30 798.3 2403.7 4664.4 156.4

01Jan2017 12:45 874.3 2417.6 4664.6 165.1

01Jan2017 13:00 958.0 2433.0 4664.8 174.9

01Jan2017 13:15 1066.2 2450.2 4665.0 186.3

01Jan2017 13:30 1268.1 2470.3 4665.3 199.9

01Jan2017 13:45 1510.7 2494.7 4665.6 217.1

01Jan2017 14:00 1673.6 2522.9 4666.0 237.6

Page 2



Storage(AC-FT)

Elevation(FT)

Outflow(CFS)

01Jan2017 14:15 1754.5 2553.2 4666.4 260.5

01Jan2017 14:30 1782.4 2584.1 4666.8 284.6

01Jan2017 14:45 1789.1 2614.8 4667.2 316.2

01Jan2017 15:00 1786.9 2644.7 4667.6 367.8

01Jan2017 15:15 1779.2 2673.4 4668.0 428.2

01Jan2017 15:30 1766.8 2700.5 4668.3 493.0

01Jan2017 15:45 1750.2 2725.9 4668.6 559.4

01Jan2017 16:00 1717.8 2749.5 4668.9 625.2

01Jan2017 16:15 1665.7 2770.9 4669.2 688.2

01Jan2017 16:30 1593.9 2789.8 4669.4 746.1

01Jan2017 16:45 1507.9 2805.9 4669.6 797.2

01Jan2017 17:00 1422.3 2819.2 4669.8 840.7

01Jan2017 17:15 1342.8 2830.1 4669.9 876.6

01Jan2017 17:30 1270.8 2838.6 4670.0 905.6

01Jan2017 17:45 1202.0 2845.2 4670.1 928.1

01Jan2017 18:00 1134.2 2850.0 4670.2 944.6

01Jan2017 18:15 1059.3 2853.1 4670.2 955.1

01Jan2017 18:30 974.2 2854.3 4670.2 959.4

01Jan2017 18:45 889.6 2853.8 4670.2 957.5

01Jan2017 19:00 810.2 2851.6 4670.2 950.0

01Jan2017 19:15 737.7 2848.1 4670.2 937.9

01Jan2017 19:30 672.0 2843.4 4670.1 921.9

01Jan2017 19:45 612.5 2837.9 4670.0 902.9

01Jan2017 20:00 558.6 2831.5 4669.9 881.5

01Jan2017 20:15 509.6 2824.6 4669.9 858.4

01Jan2017 20:30 465.3 2817.2 4669.8 833.9

01Jan2017 20:45 425.0 2809.4 4669.7 808.5

01Jan2017 21:00 388.4 2801.4 4669.6 782.7

01Jan2017 21:15 355.2 2793.1 4669.5 756.6

01Jan2017 21:30 325.0 2784.8 4669.4 730.6

01Jan2017 21:45 297.5 2776.4 4669.3 704.8

Page 3



Storage(AC-FT)

Elevation(FT)

Outflow(CFS)

01Jan2017 22:00 272.4 2768.0 4669.2 679.4

01Jan2017 22:15 249.6 2759.6 4669.0 654.5

01Jan2017 22:30 228.7 2751.3 4668.9 630.2

01Jan2017 22:45 209.6 2743.0 4668.8 606.7

01Jan2017 23:00 192.2 2734.9 4668.7 583.9

01Jan2017 23:15 176.3 2726.9 4668.6 561.8

01Jan2017 23:30 161.7 2719.0 4668.5 540.6

01Jan2017 23:45 148.4 2711.2 4668.4 520.3

02Jan2017 00:00 136.1 2703.6 4668.3 500.8

02Jan2017 00:15 124.8 2696.1 4668.2 482.1

02Jan2017 00:30 114.3 2688.8 4668.2 464.3

02Jan2017 00:45 104.6 2681.7 4668.1 447.3

02Jan2017 01:00 95.8 2674.7 4668.0 431.2

02Jan2017 01:15 87.9 2667.8 4667.9 415.8

02Jan2017 01:30 80.7 2661.1 4667.8 401.3

02Jan2017 01:45 74.0 2654.6 4667.7 387.5

02Jan2017 02:00 67.9 2648.2 4667.6 374.6

02Jan2017 02:15 62.3 2641.9 4667.6 362.3

02Jan2017 02:30 57.1 2635.7 4667.5 350.9

02Jan2017 02:45 52.3 2629.7 4667.4 340.2

02Jan2017 03:00 47.8 2623.8 4667.3 330.2

02Jan2017 03:15 43.8 2618.1 4667.2 321.0

02Jan2017 03:30 40.2 2612.4 4667.2 312.6

02Jan2017 03:45 36.9 2606.8 4667.1 305.1

02Jan2017 04:00 33.8 2601.3 4667.0 298.7

02Jan2017 04:15 31.1 2595.8 4667.0 293.9

02Jan2017 04:30 28.5 2590.4 4666.9 289.6

02Jan2017 04:45 26.1 2585.1 4666.8 285.3

02Jan2017 05:00 23.9 2579.7 4666.7 281.1

02Jan2017 05:15 21.9 2574.4 4666.7 276.9

02Jan2017 05:30 20.0 2569.2 4666.6 272.8

Page 4



Storage(AC-FT)

Elevation(FT)

Outflow(CFS)

02Jan2017 05:45 18.3 2564.0 4666.5 268.8

02Jan2017 06:00 16.8 2558.8 4666.5 264.8

02Jan2017 06:15 15.4 2553.7 4666.4 260.9

02Jan2017 06:30 14.1 2548.7 4666.3 257.0

02Jan2017 06:45 13.0 2543.7 4666.3 253.2

02Jan2017 07:00 11.9 2538.8 4666.2 249.5

02Jan2017 07:15 11.0 2533.9 4666.1 245.8

02Jan2017 07:30 10.1 2529.1 4666.1 242.2

02Jan2017 07:45 9.3 2524.3 4666.0 238.6

02Jan2017 08:00 8.6 2519.6 4666.0 235.1

02Jan2017 08:15 7.9 2514.9 4665.9 231.7

02Jan2017 08:30 7.3 2510.3 4665.8 228.3

02Jan2017 08:45 6.7 2505.8 4665.8 225.0

02Jan2017 09:00 6.1 2501.3 4665.7 221.8

02Jan2017 09:15 5.6 2496.9 4665.7 218.6

02Jan2017 09:30 5.2 2492.5 4665.6 215.5

02Jan2017 09:45 4.7 2488.2 4665.5 212.4

02Jan2017 10:00 4.3 2483.9 4665.5 209.4

02Jan2017 10:15 3.9 2479.7 4665.4 206.4

02Jan2017 10:30 3.4 2475.6 4665.4 203.5

02Jan2017 10:45 3.0 2471.4 4665.3 200.7

02Jan2017 11:00 2.6 2467.4 4665.3 197.9

02Jan2017 11:15 2.4 2463.4 4665.2 195.1

02Jan2017 11:30 2.1 2459.4 4665.2 192.5

02Jan2017 11:45 1.8 2455.5 4665.1 189.8

02Jan2017 12:00 1.6 2451.7 4665.1 187.2

Page 5


E l e v ( f t )

4,661

4,662

4,663

4,664

4,665

4,666

4,667

4,668

4,669

4,670

4,671

00:00 06:00 12:00 18:00 00:00 06:00 12:00

01Jan2017 02Jan2017

F l o w ( c f s )

200

400

600

800

1,000

1,200

1,400

1,600

1,800

2,000

Existing Dam

Run:ExDamInt10yrPostBurnNormPool Element:Existing Dam Result:Pool Elevation

Run:ExDamInt10yrPostBurnNormPool Element:Existing Dam-DAMTOP-1 Result:Dam Top 1

Run:ExDamInt10yrPostBurnNormPool Element:Existing Dam-SPILL-1 Result:Spillway 1

Run:ExDamInt10yrPostBurnNormPool Element:Existing Dam-OUTLET-1 Result:Outlet 1

Run:ExDamInt10yrPostBurnNormPool Element:Existing Dam Result:Combined Inflow

Run:ExDamInt10yrPostBurnNormPool Element:Existing Dam Result:Outflow

Int10yr_NormalPool_Graph

Appendix E Dam Break Worksheets

Eightmile Lake Break-1

Estimation of Dam Breach Characteristics for earthfill dams Reference: Technical Note 1 (2007), pages 5 to 12

[JTS], 05/07/18 page 1 of 4

Note: Tinted boxes indicate user input required.

Key equations:Breach Formation Factor BFF = Vw * Hw

Volume of material erodedCohesionless/erodible materials Vm = 3.75 BFF^0.77Erosion resistant materials Vm = 2.50 BFF^0.77

Breach geometryBase width Wb = [27 Vm - K2] / [K1]

(of breach and flow) K1 = Hb [C + (Hb Z3 / 2)]K2 = (Hb^2) [(C Zb) + (Hb Zb Z3 / 3)]

Average width of flow Wavg = Wb + Zb Hw

Top width of flow Wtop = Wb + 2 Zb Hw

Top width at dam crest Wcr = Wb + 2 Zb Hb

Time for breach developmentCohesionless/erodible materials t = 0.020 Vm^0.36Erosion resistant materials t = 0.036 Vm^0.36

Dam breach peak dischargeModified weir equation Qp = 3.1 Wavg Hw^1.5 [K3^3]

K3 = [A / (A + (t * Hw^0.5))]A = 23.4 Sa / Wavg

Froehlich equation Qp = 40.1 Vw^0.295 Hw^1.24

Project-specific data :Reference / comments :

Elevations : Input Dam crest elevation = 4667.0 ft.

WL at normal pool Piping failure Qp = 14,451 cfsBase elevation of breach = 4648.7 ft.Height (depth) of breach, Hb = 18.4 ft.Water surface elevation = 4667.0 ft. Flow control notch elevHeight over breach elev, Hw = 18.4 ft. Volume (AF)Volume of water, Vw = 1139.0 ac-ft. 4667 2714Surface area, Sa = 77.2 ac. 4649 1575

Computed Wb = 93.9 ft.

WL at dam crest Input Overtopping Qp = 14,907 cfsBase elevation of breach = 4648.7 ft.Height (depth) of breach, Hb = 18.3 ft.Water surface elevation = 4667.0 ft.Height over breach elev, Hw = 18.3 ft. Volume (AF)Volume of water, Vw = 1139.0 ac-ft. 4667 2714Surface area, Sa = 77.2 ac. 4649 1575Volume inflow during breach = 51.5 ac-ft.Sa adjusted for volume inflow = 80.7 ac. Avg inflow = 322 cfs


Eightmile Lake


[JTS], 05/07/18 page 2 of 4

Project-specific data (cont.) : Reference / comments : Geometry : Input

Crest width, C = 25 ft. Crest width from FSCrest length = 25 ft.Slope of upstream face, Z1 = 3.0 H:1VSlope of downstream face, Z2 = 3.0 H:1V

Z1 + Z2 = Z3 = 6.0 H:1V Suggested range :

Est. sideslope of breach, Zb : cohesionless resistantnormal pool, Zb = 0.25 H:1V 0.50 0.25

max. pool, Zb = 0.25 H:1V 0.50 0.25

Typical range : Erosion resistance of dam materials: Input cohesionless resistant

factor for volume (Vm) = 2.50 3.75 2.50factor for breach time (t) = 0.036 0.020 0.036

Piping failure, WL at failure = normal pool

Breach Formation Factor, BFF (--) = 20900.7Volume of material eroded, Vm = 5302.3 cu.yds.

Breach geometry: K1 = 1468.9 Froehlich equation

K2 = 5193.9 minimum widths

Base width, Wb = 93.9 ft. 43.8 ft.Average width, Wavg = 98.5 ft. 48.4 ft.Top width (flow), Wtop = 103.1 ft. 53.0 ft.Top width (crest), Wcr = 103.1 ft. 53.0 ft.Breach % of crest length = 412 % 212 %

Time for breach development, t (hrs.) = 0.79 hrs. t (min.) = 47.3 min.

Dam breach peak dischargeA = 18.3376K3 = 0.8444

Mod weir discharge, Qp = 14451 cfsFroehlich discharge, Qp = 11796 cfs T.Peak / T.Base =Use: Breach discharge, Qp = 14451 cfs 0.41 < 0.50

based on: Froehlich / mod weir

This TypicalComparisons: project range

Breach width/height 5.37 0.5 to 3.0Failure time (hrs.) 0.79 hrs. 0.2 to 4.0Peak discharge (cfs) 14451 cfs 18000 from Table 4A (cohesionless)

12000 from Table 4B (resistant)

Eightmile Lake


[JTS], 05/07/18 page 3 of 4

Overtopping failure, WL at failure = dam crest










Breach width/height 5.58 0.5 to 3.0Failure time (hrs.) 0.80 hrs. 0.2 to 4.0Breach discharge 14907 cfs 18000 from Table 4A (cohesionless)


Estimate triangular hydrograph with T.Peak and Q.Peak as calculated per Tech Note 1 methodology:

Hydrograph volume = reservoir volume at time of breach + inflows during breach

Time base for dam breach hydrograph:(Resr.Vol.) + (Vol.Inflow) = (1/2) * Q.Peak * T.Base

T.Base = [ 2 * (Resr.Vol. + Vol.Inflow) ] / (Q.Peak) (cont. on next page)

Eightmile Lake


[JTS], 05/07/18 page 4 of 4

Dam breach hydrographs :

Scenario: Piping failure, WL at normal poolReservoir volume = 1139.0 Ac-ft Surface area = 77.2 Ac.Q.Peak = 14451 cfs = 52023057 cu.ft./hr = 1194.285 Ac-ft / hour (equivalent)T.Peak = 0.79 hours = 47.3 minutesT.Base = 1.91 hours = 114.4 minutes

Hydrograph coordinates :

time, hr. Q, cfs

0 00.39 72250.79 144511.35 72251.91 0

Scenario: Overtopping, WL at dam crestReservoir volume = 1139.0 Ac-ft Surface area = 77.2 Ac.Inflow volume = 51.5 Ac-ft Avg inflow, Qin = 322 cfsQ.Peak = 14907 cfs = 53665531 cu.ft./hr = 1231.991 Ac-ft / hour (equivalent)T.Peak = 0.80 hours = 47.9 minutesT.Base = 1.93 hours = 116.0 minutes


time, hr. Q, cfs

0 00.40 74540.80 149071.37 74541.93 0

0

2000

4000

6000

8000

10000

12000

14000

16000

0.0 0.5 1.0 1.5 2.0 2.5

Dis

char

ge,

cfs

Time, hours

Dam breach hydrograph

0

2000

4000

6000

8000

10000

12000

14000

16000

0.0 0.5 1.0 1.5 2.0 2.5

Dis

char

ge,

cfs

Time, hours


Eightmile Lake Break-1


[JTS], 04/04/18 page 1 of 4

Note: Tinted boxes indicate user input required.

Key equations:Breach Formation Factor BFF = Vw * Hw

Volume of material erodedCohesionless/erodible materials Vm = 3.75 BFF^0.77Erosion resistant materials Vm = 2.50 BFF^0.77

Breach geometryBase width Wb = [27 Vm - K2] / [K1]

(of breach and flow) K1 = Hb [C + (Hb Z3 / 2)]K2 = (Hb^2) [(C Zb) + (Hb Zb Z3 / 3)]

Average width of flow Wavg = Wb + Zb Hw

Top width of flow Wtop = Wb + 2 Zb Hw

Top width at dam crest Wcr = Wb + 2 Zb Hb

Time for breach developmentCohesionless/erodible materials t = 0.020 Vm^0.36Erosion resistant materials t = 0.036 Vm^0.36

Dam breach peak dischargeModified weir equation Qp = 3.1 Wavg Hw^1.5 [K3^3]

K3 = [A / (A + (t * Hw^0.5))]A = 23.4 Sa / Wavg

Froehlich equation Qp = 40.1 Vw^0.295 Hw^1.24

Project-specific data :Reference / comments :

Elevations : Input Dam crest elevation = 4667.0 ft.

WL at normal pool Piping failure Qp = 7,693 cfsBase elevation of breach = 4648.7 ft.Height (depth) of breach, Hb = 18.4 ft.Water surface elevation = 4661.7 ft. Flow control notch elevHeight over breach elev, Hw = 13.1 ft. Volume (AF)Volume of water, Vw = 1139.0 ac-ft. 4667 2714Surface area, Sa = 77.2 ac. 4649 1575


WL at dam crest Input Overtopping Qp = 5,013 cfsBase elevation of breach = 4660.0 ft.Height (depth) of breach, Hb = 7.0 ft.Water surface elevation = 4667.0 ft.Height over breach elev, Hw = 7.0 ft. Volume (AF)Volume of water, Vw = 484.0 ac-ft. 4667 2714Surface area, Sa = 77.2 ac. 4660 2230Volume inflow during breach = 50.0 ac-ft.Sa adjusted for volume inflow = 85.2 ac. Avg inflow = 235 cfs


Eightmile Lake


[JTS], 04/04/18 page 2 of 4

Project-specific data (cont.) : Reference / comments : Geometry : Input

Crest width, C = 30 ft.Crest length = 50 ft.Slope of upstream face, Z1 = 3.0 H:1VSlope of downstream face, Z2 = 3.0 H:1V

Z1 + Z2 = Z3 = 6.0 H:1V Suggested range :

Est. sideslope of breach, Zb : cohesionless resistantnormal pool, Zb = 0.25 H:1V 0.50 0.25

max. pool, Zb = 0.25 H:1V 0.50 0.25

Typical range : Erosion resistance of dam materials: Input cohesionless resistant

factor for volume (Vm) = 2.50 3.75 2.50factor for breach time (t) = 0.036 0.020 0.036

Piping failure, WL at failure = normal pool










Breach width/height 3.83 0.5 to 3.0Failure time (hrs.) 0.72 hrs. 0.2 to 4.0Peak discharge (cfs) 7693 cfs 18000 from Table 4A (cohesionless)


Eightmile Lake


[JTS], 04/04/18 page 3 of 4

Overtopping failure, WL at failure = dam crest










Breach width/height 15.26 0.5 to 3.0Failure time (hrs.) 0.49 hrs. 0.2 to 4.0Breach discharge 5013 cfs 18000 from Table 4A (cohesionless)


Estimate triangular hydrograph with T.Peak and Q.Peak as calculated per Tech Note 1 methodology:

Hydrograph volume = reservoir volume at time of breach + inflows during breach

Time base for dam breach hydrograph:(Resr.Vol.) + (Vol.Inflow) = (1/2) * Q.Peak * T.Base

T.Base = [ 2 * (Resr.Vol. + Vol.Inflow) ] / (Q.Peak) (cont. on next page)

Eightmile Lake


[JTS], 04/04/18 page 4 of 4

Dam breach hydrographs :

Scenario: Piping failure, WL at normal poolReservoir volume = 1139.0 Ac-ft Surface area = 77.2 Ac.Q.Peak = 7693 cfs = 27695398 cu.ft./hr = 635.799 Ac-ft / hour (equivalent)T.Peak = 0.72 hours = 43.1 minutesT.Base = 3.58 hours = 215.0 minutes


time, hr. Q, cfs

0 00.36 38470.72 76932.15 38473.58 0

Scenario: Overtopping, WL at dam crestReservoir volume = 484.0 Ac-ft Surface area = 77.2 Ac.Inflow volume = 50.0 Ac-ft Avg inflow, Qin = 235 cfsQ.Peak = 5013 cfs = 18047474 cu.ft./hr = 414.313 Ac-ft / hour (equivalent)T.Peak = 0.49 hours = 29.4 minutesT.Base = 2.58 hours = 154.7 minutes


time, hr. Q, cfs

0 00.24 25070.49 50131.53 25072.58 0

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

0.0 1.0 2.0 3.0 4.0

Dis

char

ge,

cfs

Time, hours


0

1000

2000

3000

4000

5000

6000

0.0 0.5 1.0 1.5 2.0 2.5 3.0

Dis

char

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Time, hours


Appendix F HEC-RAS Results

0 20000 40000 60000 800001000

1200

1400

1600

1800

2000

2200

EightmileEAPJTSUnsteady Plan: Overtopping_Breach_15000 5/16/2018

Main Channel Distance (ft)

Elev

atio

n (ft

)

Legend

WS Max WS

Ground

XS-2

XS-3

XS-4

XS-5

XS-6

XS-7

XS-8

XS-9

XS-1

0

XS-1

1XS

-12

XS-1

3

XS-1

4

XS-1

5

Icicle Creek Lower Icicle Creek Lower

Mid

Icicle Creek Hatchery

Icicle Creek Upper

Page 1

0 200 400 600 8001900

1920

1940

1960

1980

2000

2020

EightmileEAPJTSUnsteady Plan: Overtopping_Breach_15000 5/16/2018 River = Icicle Creek Reach = Upper RS = 50305.54 XS-15 XS-15

Station (ft)

Elev

atio

n (ft

)

Legend

WS Max WS

-2 ft/s

0 ft/s

2 ft/s

4 ft/s

6 ft/s

8 ft/s

10 ft/s

Ground

Bank Sta

0 500 1000 1500 2000 25001800

1850

1900

1950

2000

2050

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2150


Station (ft)

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atio

n (ft

)

Legend

WS Max WS

0 ft/s

5 ft/s

10 ft/s

15 ft/s

20 ft/s

Ground

Bank Sta

Page 2

0 500 1000 1500 20001600

1700

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1900

2000

2100

2200


Station (ft)

Elev

atio

n (ft

)

Legend

WS Max WS

0 ft/s

5 ft/s

10 ft/s

15 ft/s

20 ft/s

Ground

Levee

Bank Sta

0 200 400 600 800 1000 1200 1400 1600 18001300

1350

1400

1450

1500

1550

1600

1650

1700


Station (ft)

Elev

atio

n (ft

)

Legend

WS Max WS

0 ft/s

5 ft/s

10 ft/s

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20 ft/s

Ground

Bank Sta

Page 3

0 200 400 600 800 1000 1200 1400 16001250

1300

1350

1400

1450

1500

1550

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1650


Station (ft)

Elev

atio

n (ft

)

Legend

WS Max WS

0 ft/s

2 ft/s

4 ft/s

6 ft/s

8 ft/s

10 ft/s

12 ft/s

14 ft/s

16 ft/s

Ground

Bank Sta

0 500 1000 1500 20001150

1200

1250

1300

1350

1400

1450


Station (ft)

Elev

atio

n (ft

)

Legend

WS Max WS

2 ft/s

4 ft/s

6 ft/s

8 ft/s

10 ft/s

12 ft/s

14 ft/s

16 ft/s

Ground

Bank Sta

Page 4

0 500 1000 1500 2000 2500 3000 35001120

1140

1160

1180

1200

1220


Station (ft)

Elev

atio

n (ft

)

Legend

WS Max WS

2 ft/s

4 ft/s

6 ft/s

8 ft/s

10 ft/s

12 ft/s

Ground

Bank Sta

0 500 1000 1500 20001125

1130

1135

1140

1145

1150

1155

EightmileEAPJTSUnsteady Plan: Overtopping_Breach_15000 5/16/2018 River = Icicle Creek Reach = Hatchery RS = 354.6978 XS-8 XS-8

Station (ft)

Elev

atio

n (ft

)

Legend

WS Max WS

14 ft/s

16 ft/s

18 ft/s

20 ft/s

22 ft/s

24 ft/s

26 ft/s

Ground

Levee

Ineff

Bank Sta

Page 5

0 200 400 600 800 1000 1200 1400 1600 18001100

1120

1140

1160

1180

1200

1220

1240

1260

EightmileEAPJTSUnsteady Plan: Overtopping_Breach_15000 5/16/2018 River = Icicle Creek Reach = Lower Mid RS = 17441.21 XS-8 XS-8

Station (ft)

Elev

atio

n (ft

)

Legend

WS Max WS

1 ft/s

2 ft/s

3 ft/s

4 ft/s

5 ft/s

Ground

Levee

Bank Sta

0 1000 2000 3000 4000 50001100

1150

1200

1250

1300

1350

EightmileEAPJTSUnsteady Plan: Overtopping_Breach_15000 5/16/2018 River = Icicle Creek Reach = Lower RS = 14297.71 XS-7 XS-7

Station (ft)

Elev

atio

n (ft

)

Legend

WS Max WS

0 ft/s

2 ft/s

4 ft/s

6 ft/s

8 ft/s

Ground

Levee

Bank Sta

Page 6

0 1000 2000 3000 4000 50001100

1120

1140

1160

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1200

1220

1240

1260


Station (ft)

Elev

atio

n (ft

)

Legend

WS Max WS

0 ft/s

1 ft/s

2 ft/s

3 ft/s

4 ft/s

5 ft/s

6 ft/s

Ground

Levee

Bank Sta

0 500 1000 1500 2000 2500 30001100

1105

1110

1115

1120

1125

1130


Station (ft)

Elev

atio

n (ft

)

Legend

WS Max WS

0 ft/s

1 ft/s

2 ft/s

3 ft/s

4 ft/s

5 ft/s

Ground

Levee

Bank Sta

Page 7

0 500 1000 1500 2000 25001100

1102

1104

1106

1108

1110

1112

1114


Station (ft)

Elev

atio

n (ft

)

Legend

WS Max WS

0 ft/s

1 ft/s

2 ft/s

3 ft/s

4 ft/s

Ground

Levee

Bank Sta

0 1000 2000 3000 4000 5000 60001050

1100

1150

1200

1250

1300

1350

EightmileEAPJTSUnsteady Plan: Overtopping_Breach_15000 5/16/2018 River = Icicle Creek Reach = Lower RS = 255 XS-3 XS-3

Station (ft)

Elev

atio

n (ft

)

Legend

WS Max WS

0 ft/s

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6 ft/s

8 ft/s

Ground

Levee

Bank Sta

Page 8

0 1000 2000 3000 4000 50001050

1100

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1250

1300

1350


Station (ft)

Elev

atio

n (ft

)

Legend

WS Max WS

8 ft/s

10 ft/s

12 ft/s

14 ft/s

16 ft/s

18 ft/s

20 ft/s

Ground

Bank Sta

0 500 1000 1500 2000 2500 30001000

1050

1100

1150

1200

1250

1300


Station (ft)

Elev

atio

n (ft

)

Legend

WS Max WS

2 ft/s

4 ft/s

6 ft/s

8 ft/s

10 ft/s

12 ft/s

14 ft/s

Ground

Bank Sta

Page 9

HEC-RAS Plan: Overtopping_15000 Profile: Max WSReach River Sta Q Total Min Ch El Max Chl Dpth W.S. Elev Crit W.S. E.G. Elev E.G. Slope Vel Chnl Flow Area Top Width Froude # Chl

(cfs) (ft) (ft) (ft) (ft) (ft) (ft/ft) (ft/s) (sq ft) (ft) Upper 54962.83 2887.00 2056.00 2.46 2058.46 2059.29 0.029394 7.28 396.72 175.27 0.85Upper 53024.16 2887.29 1998.00 3.57 2001.57 2002.64 0.028022 8.29 348.20 121.13 0.86Upper 51684.1 2886.86 1959.00 4.26 1963.26 1964.14 0.027746 7.52 383.70 153.55 0.84Upper 51037.99 2887.03 1939.00 5.24 1944.24 1944.12 1946.26 0.032758 11.39 253.48 58.19 0.96Upper 50785.52 2886.99 1931.00 3.63 1934.63 1935.53 0.023695 7.62 378.83 132.01 0.79Upper 50305.54 XS-15 2885.80 1917.00 5.88 1922.88 1923.12 0.003066 3.87 746.61 153.58 0.31Upper 49756.12 17736.96 1900.00 8.61 1908.61 1909.07 1912.80 0.033097 16.45 1094.80 164.44 1.09Upper 49716.59 17736.48 1898.00 9.22 1907.22 1907.97 1911.67 0.037102 17.07 1093.25 180.43 1.15Upper 49093.42 17723.27 1881.00 6.21 1887.21 1889.06 0.024394 10.92 1631.51 371.26 0.88Upper 48345.38 17702.73 1864.00 5.99 1869.99 1871.35 0.017416 9.40 1926.24 413.25 0.75Upper 47503.77 17670.83 1847.00 8.71 1855.71 1857.67 0.014828 11.34 1646.48 260.27 0.73Upper 46467.44 17298.29 1831.00 15.99 1846.99 1847.29 0.001120 4.56 4524.41 507.03 0.22Upper 45115.09 XS-14 17279.32 1829.00 8.92 1837.92 1839.10 1843.62 0.042630 19.16 905.31 127.62 1.24Upper 43954.69 17278.21 1779.00 9.08 1788.08 1789.65 1794.18 0.056742 19.81 874.04 141.77 1.39Upper 42768 17277.06 1715.45 9.07 1724.52 1724.47 1726.69 0.025200 12.36 1673.17 416.54 0.92Upper 40830.82 XS-13 17270.84 1663.59 12.97 1676.56 1677.40 1681.64 0.024785 18.12 976.92 110.35 0.99Upper 39502.82 17267.99 1635.00 10.23 1645.23 1648.65 0.019667 14.87 1186.05 145.21 0.87Upper 38736.66 17266.21 1620.00 9.08 1629.08 1629.47 1633.31 0.030382 16.52 1061.99 154.07 1.06Upper 37515.71 17264.70 1580.61 10.36 1590.97 1592.72 1598.22 0.049279 21.61 805.32 106.52 1.34Upper 35978.31 17264.05 1502.00 14.26 1516.26 1518.80 1525.20 0.054705 24.01 731.13 93.75 1.40Upper 34758.6 17263.17 1440.00 11.19 1451.19 1452.72 1458.42 0.041086 21.60 808.79 92.54 1.25Upper 34275.95 17263.11 1420.00 12.33 1432.33 1432.79 1437.76 0.029175 18.73 937.51 105.87 1.06Upper 33738.44 17258.97 1407.00 14.25 1421.25 1423.12 0.008109 10.98 1589.56 146.34 0.58Upper 32671.28 17255.67 1399.00 7.86 1406.86 1409.08 1414.37 0.076561 21.99 790.69 145.09 1.61Upper 31421.65 XS-12 17254.98 1309.00 9.63 1318.63 1319.14 1323.26 0.032367 17.28 1013.23 139.89 1.09Upper 30588.39 XS-11 17317.47 1283.91 8.32 1292.23 1292.54 1295.84 0.032518 15.25 1148.00 193.97 1.06Upper 29373.24 17314.91 1243.00 9.87 1252.87 1253.67 1256.86 0.024434 16.26 1221.49 271.11 0.97Upper 28237.61 17311.67 1214.00 11.70 1225.70 1229.33 0.017475 15.32 1162.27 129.50 0.84Upper 27013.73 17307.29 1194.00 9.92 1203.92 1203.65 1207.45 0.023307 15.10 1166.24 157.86 0.93Upper 26177.38 17304.32 1172.00 14.90 1186.90 1186.32 1191.49 0.018624 17.38 1079.08 117.79 0.87Upper 25680.01 17303.08 1166.00 11.12 1177.12 1177.00 1181.61 0.024649 17.05 1043.94 128.07 0.98Upper 25032.33 XS-10 17301.20 1152.00 9.66 1161.66 1161.62 1164.76 0.023247 14.26 1302.96 245.30 0.92Upper 24510.22 17259.15 1145.00 9.18 1154.18 1154.97 0.006127 7.21 2535.70 417.25 0.47Upper 23377.89 17212.26 1135.00 12.04 1147.04 1149.00 0.009121 11.35 1610.01 179.86 0.61Upper 22829.34 XS-9 17204.76 1127.74 15.46 1143.21 1144.77 0.005581 10.27 1975.54 247.75 0.49Hatchery 3724.057 7601.24 1129.00 14.20 1143.21 1143.47 0.000519 4.13 1840.16 166.96 0.22Hatchery 2574.75 7602.44 1129.00 13.80 1142.80 1143.10 0.000623 4.39 1732.03 161.40 0.24Hatchery 1509.345 7551.14 1129.00 12.88 1141.88 1142.21 0.000752 4.60 1641.46 164.10 0.26Hatchery 668.1756 7325.93 1129.00 12.22 1141.22 1141.52 0.000718 4.40 1663.86 173.17 0.25Hatchery 354.6978 XS-8 7867.82 1127.69 6.18 1133.87 1135.88 1140.53 0.066897 20.70 380.08 118.52 2.04Hatchery 177.4453 5921.57 1114.00 14.52 1128.52 1128.95 0.000816 5.24 1130.84 84.54 0.25Lower Mid 22619.95 9603.53 1128.00 15.20 1143.21 1143.39 0.001337 4.65 3326.68 368.83 0.23

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HEC-RAS Plan: Overtopping_15000 Profile: Max WS (Continued)Reach River Sta Q Total Min Ch El Max Chl Dpth W.S. Elev Crit W.S. E.G. Elev E.G. Slope Vel Chnl Flow Area Top Width Froude # Chl

(cfs) (ft) (ft) (ft) (ft) (ft) (ft/ft) (ft/s) (sq ft) (ft) Lower Mid 22578.3 9577.36 1127.00 15.29 1142.29 1143.09 1149.04 0.042691 20.84 459.55 40.69 1.09Lower Mid 22235.43 9104.49 1123.70 13.84 1137.54 1137.65 0.000842 3.08 4046.52 608.84 0.18Lower Mid 22017.84 9082.13 1126.00 11.37 1137.37 1137.49 0.000684 2.88 3825.44 563.86 0.16Lower Mid 21387.29 8967.31 1124.00 12.78 1136.78 1136.98 0.001079 3.82 3203.79 528.87 0.21Lower Mid 20776.34 8900.44 1123.00 12.56 1135.57 1136.07 0.002510 6.15 2054.37 409.08 0.32Lower Mid 20223.67 8842.59 1121.00 13.57 1134.57 1134.90 0.001389 4.74 2143.60 282.40 0.24Lower Mid 19707.18 8771.14 1121.00 12.61 1133.61 1134.08 0.002029 5.61 1816.34 271.81 0.29Lower Mid 19246.99 8679.69 1120.00 12.63 1132.63 1133.11 0.002242 5.72 1847.80 335.43 0.31Lower Mid 18735.83 8541.74 1119.08 12.65 1131.73 1132.07 0.001714 4.92 2202.07 396.32 0.27Lower Mid 18277.82 8482.89 1119.00 12.20 1131.21 1131.39 0.000965 3.71 3246.70 587.85 0.20Lower Mid 17441.21 XS-8 8196.74 1119.00 10.94 1129.94 1130.22 0.001862 4.90 3047.89 847.42 0.27Lower Mid 16890.05 8221.28 1119.00 10.11 1129.11 1129.17 0.000542 2.43 5268.03 858.98 0.14Lower Mid 16296.95 8129.74 1114.00 14.52 1128.52 1128.78 0.000968 4.26 2572.55 380.15 0.21Lower 15947.61 14051.31 1113.12 15.40 1128.52 1128.72 0.000360 3.75 5699.95 1051.01 0.19Lower 15502.25 14184.28 1113.00 15.29 1128.29 1128.55 0.000549 4.71 6357.37 1160.85 0.23Lower 14297.71 XS-7 13985.92 1111.34 15.14 1126.48 1127.14 0.001260 7.26 4398.01 1560.89 0.35Lower 12523.53 12034.38 1110.00 12.98 1122.98 1123.73 0.001633 7.30 2476.03 491.54 0.39Lower 11499.97 10868.09 1110.00 10.48 1120.48 1121.13 0.001806 6.91 2726.14 837.05 0.40Lower 7678.969 10411.51 1107.00 10.93 1117.93 1118.03 0.000969 2.61 4762.75 1862.22 0.25Lower 6178.466 XS-6 11067.39 1106.00 10.84 1116.84 1117.24 0.001170 5.29 2791.98 462.49 0.32Lower 5178.779 11569.35 1106.93 8.88 1115.81 1115.96 0.000784 4.01 6925.28 1899.79 0.26Lower 3426.354 XS-5 10657.86 1104.14 10.03 1114.03 1114.19 0.000776 4.22 6845.26 2158.39 0.26Lower 2567.128 10551.83 1103.00 10.47 1113.34 1113.48 0.000605 3.91 6966.43 1932.94 0.23Lower 1664.219 10429.04 1101.00 10.89 1111.89 1112.42 0.001637 6.47 3047.18 817.16 0.37Lower 936.7949 XS-4 10257.60 1101.00 10.20 1111.20 1111.41 0.000796 3.88 3347.63 622.61 0.25Lower 292.6098 10192.11 1099.00 11.53 1110.53 1110.88 0.001091 4.72 2192.67 319.59 0.30Lower 280 10213.43 1097.00 13.62 1110.62 1110.66 0.000112 1.75 6257.84 862.48 0.10Lower 255 XS-3 20258.70 1097.00 11.71 1108.71 1109.37 0.001494 6.85 4300.93 783.99 0.37Lower 219 20242.64 1095.00 9.04 1104.04 1104.78 0.002543 7.10 3238.77 547.72 0.46Lower 182 20192.44 1093.00 7.58 1100.58 1100.93 0.001450 5.02 4927.96 791.53 0.34Lower 146 XS-2 20171.07 1080.00 12.93 1092.93 1096.13 0.008126 14.34 1406.23 154.02 0.84Lower 109 20166.54 1069.00 9.30 1078.30 1079.17 0.002882 7.51 2686.63 364.48 0.49Lower 73 20155.41 1050.00 11.54 1061.54 1063.23 0.004036 10.44 1930.25 200.81 0.59Lower 36.5 20136.83 1040.00 12.43 1052.43 1053.34 0.001932 7.64 2634.28 255.18 0.42Lower 0 XS-1 20117.41 1033.00 10.54 1043.54 1039.35 1044.53 0.002345 7.98 2521.14 264.57 0.46

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preliminary hydrologic and hydraulic analyses · l:\projects\icicle and peshastin irrigation...

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