powers creek c watershed - british...

POWERS CREEK COMMUNITY

WATERSHED

CUMULATIVE HYDROLOGIC IMPACT ASSESSMENT OF MOUNTAIN PINE BEETLE INFESTED STANDS AND PROPOSED RETENTION

PLAN

PREPARED FOR

BY

JANUARY 2008

Powers Creek MPB/Hydrology Assessment

544-004/26106/January 2008 Page i of i

TABLE OF CONTENTS

1. INTRODUCTION .................................................................................................................... 1

2. ASSESSMENT.......................................................................................................................... 2 2.1 CURRENT WATERSHED CONDITION ...................................................................................... 2 2.2 FIELD INSPECTIONS ............................................................................................................... 2 2.3 HYDROLOGIC IMPACT OF LOSS OF MATURE LODGEPOLE PINE ............................................ 2 2.4 HYDROLOGIC IMPACTS OF PROPOSED RETENTION PLAN ................................................... 10

3. CONCLUSIONS..................................................................................................................... 11

4. RECOMMENDATIONS ....................................................................................................... 12


POWERS CREEK COMMUNITY WATERSHED CUMULATIVE HYDROLOGIC IMPACT ASSESSMENT OF MOUNTAIN PINE

BEETLE INFESTED STANDS AND PROPOSED RETENTION PLAN 1. INTRODUCTION

This report has been prepared for Tolko Industries Limited (Tolko) to update the hydrologic conditions for the two sub-basins in the Powers Creek watershed within TFL 49. This report will address the ECAs and assess the potential hydrologic impacts of the loss of forest cover as a result of the expansion of the mountain pine beetle as input to the development of mountain pine beetle salvage plans. The report also provides summary comments regarding the proposed retention plans. This report only addresses the North Powers and West Powers Creek sub-basins that are within TFL 49 that are managed by Tolko. The remainder of the watershed is held under forest licenses managed by others. The remainder of the watershed will be addressed in a separate report to be completed at a later date. The previous watershed assessment for the Powers Creek watershed was completed in 2001. The hazard ratings for these two sub-basins were all rated as low except for the channel stability in North Powers that was rated as moderate. The loss of most or all of the remaining mature lodgepole pine in Tolko’s TFL in the Powers Creek watershed will affect the hydrology of the two sub-basins. The mature lodgepole pine in this watershed was originally attacked in the late 1970s resulting in an aggressive harvesting program. However the areas that were harvested at that time are substantially hydrologically recovered. It will be the loss of canopy and related decrease in evapotranspiration combined with increased water yields, particularly in the snow accumulation zone in the upper watershed area that will impact the hydrology. The primary area of concern is the snow sensitive zone, the source for the spring freshet and peak stream flows. Loss of canopy closure results in increased snow accumulation on the ground and subsequent increase in melt rates. The decrease in evapotranspiration due to the tree mortality further exacerbates the problem resulting in the potential for even greater water yields. The impacts on the magnitude and the timing of peak flows are a concern in the areas above the reservoirs due to the location of the snow sensitive zone as well as in the southwest corner of the watershed that drains into the mainstem above the intake. Tolko provided the data used to carry out the hydrologic assessments. The results of the initial assessment were used to provide guidance in the development of the retention plan. The impacts of the proposed salvage logging, as presented in the retention plan were subsequently reviewed and the final recommendations for salvage logging are provided in this report.

Powers Creek is a community watershed for the Westbank Irrigation District (WID). The watershed drains to the east off the Thompson Plateau into Okanagan Lake. The portion of the watershed included in this review has an area of approximately 9,547 ha [refer to Map 1 – Appendix A]. Storage has been developed in the Lambly Reservoir, Jackpine Reservoir and Dobbin/Horseshoe Reservoir. The community watershed intake is located in the lower Powers Creek watershed approximately 11 km downstream from the Lambly Reservoir.

The terrain in the project area is generally benign gently rolling plateau with no evidence of instability. The soil erosion hazard is generally moderate on the glacial till soils. Although the mainstem channels are typically stable they will be susceptible to impacts from the loss of


544-004/26106/January 2008 Page 2 of 12

canopy in the riparian areas where mature lodgepole pine is the dominant species, and they will be susceptible to increase in peak flow as the pine dies. For the purposes of this assessment the watershed has been sub-divided in two sub-basins, the North Powers sub-basin and the West Powers sub-basin. The point of interest is the confluence of the two sub-basins on Powers Creek.

2. ASSESSMENT

2.1 Current Watershed Condition The current watershed condition is based on the ECAs to December 31, 2006. The values presented in Table 1 illustrate the estimated hydrologic recovery for all blocks including any blocks planned for harvest by December 31, 2006. The values of interest are those for the snow sensitive zone (SSZ) that is defined as the upper 40% of the watershed. For the SSZ, the current ECAs based on past harvesting are 33% in North Powers and 23.3% in West Powers (refer to Table 1). The total area may be harvested by December 31, 2006 is 1,203.8 ha (35.7% of the sub-basin) in North Powers and 1,823.7 ha (29.5% of the sub-basin in West Powers). The ECA for the SSZ in both sub-basins translates into low peak flow hazards. The data summaries are provided in Appendix B.

Table 1.

Current ECAs (December 31, 2006)

Drainage Area (ha)

Total Area Harvested (ha)/(%)

Current Total ECA (ha)/(%)

Current ECA below

snowline (ha)(%)

Current ECA above snowline

(ha)(%)

North Powers

sub-basin 3,375.2 1,203.8/35.7 795.7/23.6

218.1/13.4

577.6/33.0

West

Powers sub-basin

6,172.1

1,823.7/29.5

1,169.5/18.9

538.4/15.5

631.2/23.3

Growth of trees is modeled using Variable Density Yield Predictor (VDYP) and site index values. Site index values are updated using the BC Ministry of Forests Site Index estimates by Site Series (SIBEC) -

Second Approximation published in 2003. All stands ≥12m in height are considered to be fully recovered, hydrologically, and have been excluded from the

ECA calculations. Snow zone ECA is calculated as the non-recovered area in the snow sensitive zone divided by the total area of

the snow sensitive zone.

2.2 Field Inspections Due to an early snowfall in the fall of 2006 no field review were completed in these sub-basins.

2.3 Hydrologic Impact of Loss of Mature Lodgepole Pine As indicated previously the zone of specific interest is that area within the snow sensitive zone. For this assessment the snow sensitive zone in the Powers Creek sub-basins that contributes to the peak flow during the spring runoff is approximated as the upper 40% of the watershed [refer to Map 1, Appendix A]. This area is based on the results of snowline monitoring of other watersheds in the Okanagan Valley since 19991.

Table 2 provides an estimate of the ECAs given the loss of all mature lodgepole pine forest cover plus all harvesting to the end of 2006. The pine considered in Table 2 is the

1 Dobson Engineering Ltd., 2002, Synthesis of the 1999 to 2001 Snow Course and Snowline Results For the

Chase Creek Watershed.


544-004/26106/January 2008 Page 3 of 12

“net area” of pine for all polygons >40% pine. The definition of net area is the area remaining after the area for all non-pine species have been excluded.

Table 2.

ECAs assuming loss of all mature Lodgepole Pine over the next 3-5 years including areas harvested to December 31, 2006

Drainage Area (ha)

Total Area Impacted incl MPB (ha)/(%)

Total ECA1 (Net Area) (ha)/(%)

ECA below snowline1 (Net Area) (ha)/(%)

Area above

snowline (ha)

ECA above snowline1 (Net Area) (ha)/(%)

North Powers sub-basin

3,375.2

2,246.4/66.6

1,838.3/54.5

753.1/46.4

1,750.3

1,085.2/63.0

West Powers sub-basin

6,172.1

3,283.0/53.2

2,628.8/42.6

1,187.9/34.3

2,709.1

1,440.9/53.2

1. The area value in this column is the combined area of past harvesting (recovery modeled) + the net area of

lodgepole pine. The % value is the ECA for the area of past harvesting as a % + the net pine area as a %, not discounted since it is a net value, i.e. all non-pine species removed. This ECA represents a “worst-case” from a hydrologic perspective as it assumes that when the mature pine dies it will act hydrologically similar to a clear-cut.

In the following discussion the term “effective ECA” is used to describe the potential hydrologic impacts of the loss of the mature pine. The “effective ECA” is the ECA for the gross area of a forest cover polygon that contains >40% mature pine as well as other non-pine species, combined with the ECA for all past harvesting – limited to the snow sensitive zone. The effective ECA is used since it more accurately reflects how salvage harvesting might impact the hydrology. To calculate the ECA value, the area has been discounted by 50% to approximate the impact on snow accumulation and melt in mixed stands (>40% pine) including dead pine and with consideration for any secondary structure. Increases in peak flows generated in the snow sensitive zone typically result from increased snow accumulation and faster melt rates. The effective ECA value is different from the ECA values in Table 2 that are based on net areas of pine (as has been discussed previously). Unfortunately there is very limited data available regarding the effect on runoff from the loss of canopy in dead pine stands2.

It has been documented that there is still some interception of snow in dead stands therefore the accumulation of snow on the ground will be greater than under a live stand but less than for a clear-cut. Also the standing dead stems may affect the melt rates that will be greater than for a live stand but likely less than for a clear-cut.

Preliminary research results for stands in the northern interior indicate that the potential ECA for dead pine stands in that area may be in the 50% range of those for a clear-cut. The adjustment factor is intended to represent the “average” stand; the actual value will depend upon the species composition and the secondary structure. There are a number of research projects in progress3 that are focused on this issue by researchers from the Ministry of Forests and Range in Kamloops, Williams Lake and Prince George, various

2 Review and Synthesis of Potential Hydrologic Impacts of Mountain Pine Beetle and Related Harvesting Activities in British Columbia, J.F. Hélie; D.L. Peters; K.R. Tattrie; J.J. Gibson, Mountain Pine Beetle Initiative Working Paper 2005–23, Canadian Forestry Service, 2005; Determining the impact of MPB-killed forest and elevated harvesting on snow accumulation and the projected impacts on melt and peak flow. BC Ministry of Forests, S. Boon, UNBC, FIA-FSP Report #M065006; Snow Surveys in Supply Block F Prince George, January to April 2006, P. Beaudry, P. Beaudry and Associates Ltd. CANFOR report, 2006. 3 Projects include work by: R. Winkler, MoFR, Kamloops (research projects include Upper Penticton Creek and Mason Lake); P. Teti, MoFR, Williams Lake (research projects in various pine stands in the Cariboo),


544-004/26106/January 2008 Page 4 of 12

consultants and the Faculty of Forestry at UBC. Until the results from these research projects are available to better define how snow accumulates and melts in dead pine stands, the application of a 50% adjustment factor for the ECAs from live stands to dead stands is the recommended for the Okanagan. [The decision to apply a factor to adjust the ECAs from those of a clear-cut evolved from a review of the limited data available for both the southern and northern interior and from discussions with R. Winkler and P. Teti, Research Hydrologists with the MoFR.]

Data on the pine stands by polygon was provided by the licensees including a percentage of mature pine for polygons <40% pine, 40-50%, 51-60%, 61-70% and >70% pine. For the purposes of the assessment, those stands with <40% mature pine were not considered in the proposed harvesting since even if all the mature pine was killed by the beetle, it was assumed that there was no hydrologic impact due to the extent of non- pine species. For those polygons where the mature pine ranged from 40% - 70% of the stand, the effective area of the polygon was adjusted using a factor based on the analysis undertaken for the Watershed Assessment Guidebook, 1999 version, Appendix 24 to compensate for the hydrologic value of the non-pine species. A summary of the gross pine distribution is provided in Tables 3 and 4 and Figures 1 - 4. The gross pine distribution is the gross area of polygons with mature pine >40% including all species. These values are important from a forest planning perspective as they represent the actual areas that might be salvaged and include all the species as identified in the MoFR forest cover database.

North Powers sub-basin A review of Figure 1 indicates that for the SSZ past harvesting has occurred on 49% of the area, the mature pine >40% accounts for a further 34.1% of the area. Stands with pine <40% plus the non-pine types account for a total of only 17% of the area. The total area that will impact the hydrology will total ~83% of the entire snow sensitive zone area. For the total sub-basin, referring to Figure 2, past logging plus the pine leading stands account for approximately 73% of the sub-basin with the stands with <40% mature pine plus the non-pine stands accounting for ~27% of the sub-basin. The effective ECAs assuming all the mature pine dies would be ~83% for the SSZ and ~73% for the entire sub-basin. The potential peak flow impacts have been assessed with consideration for the results of the research carried out in the Upper Penticton Creek watershed by the research staff with the Southern Interior Forest Region and reported in Extension Note 675, as well as known channel conditions. Based on the results reported in the extension note, an ECA of 83% would increase the 50-year peak flow by approximately 39% for the SSZ that would represent a high peak flow hazard.

4 Interior Watershed Assessment Procedure Guidebook (IWAP), Ministry of Forests, Second edition, version

2.1, 1999. 5 Extension Note 67, Schnorbus et al, Ministry of Forests, Forest Sciences Program, 2004


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Forest Cover Distribution in Watershed - Above, Retained Data

12%

22%

2%

0%

3%

57%

4%

<40%>70%40-50%51-60%61-70%LoggedNon-Pine

Table 3. Distribution of Mature Lodgepole Pine in the North Powers Sub-basin

BAND PL_BAND Gross Net Area <40 186.5 0.0>70 341.1 339.0

40-50 27.3 10.951-60 0.0 0.061-70 51.6 36.1Log 856.3 824.8

Above

No Pine 64.4 0.0<40 309.7 0.0>70 470.5 452.0

40-50 41.6 16.751-60 11.9 4.761-70 14.8 9.0Log 387.4 378.3

Below

No Pine 298.4 0.0

Figure 1. Distribution of Mature Pine in North Powers Sub-basin

Above Only Range Gross %of Total <40% 186.5 12.2>70% 341.1 22.3

40-50% 27.3 1.851-60% 0.0 0.061-70% 51.6 3.4Logged 856.3 56.1

Non-Pine 64.4 4.2 1,527.3 100.0


544-004/26106/January 2008 Page 6 of 12

Forest Cover Distribution in Watershed - Total, Retained Data

16%

27%

2%0%2%

41%

12%

<40%>70%40-50%51-60%61-70%LoggedNon-Pine

Figure 2. Distribution of Mature Pine in North Powers Sub-basin

Above & Below Range Gross %of Total <40% 496.2 16.2>70% 811.6 26.5

40-50% 68.9 2.351-60% 11.9 0.461-70% 66.3 2.2Logged 1,243.7 40.6

Non-Pine 362.8 11.8 3,061.5 100.0


544-004/26106/January 2008 Page 7 of 12

West Powers sub-basin A review of Figure 3 indicates that for the SSZ past harvesting has occurred on 34.3% of the area, the mature pine >40% accounts for a further 38.5% of the area. Stands with pine <40% plus the non-pine types account for a total of only 27.5% of the area. The total area that will impact the hydrology will total ~73% of the entire snow sensitive zone area. For the total watershed, referring to Figure 4, past logging plus the pine leading stands account for approximately 63% of the sub-basin with the stands with <40% mature pine plus the non-pine stands accounting for ~37% of the sub-basin. The “effective” ECAs for the watershed assuming all the mature pine dies would be ~73% for the SSZ and ~63% for the entire sub-basin. The potential peak flow impacts have been assessed with consideration for the results of the research carried out in the Upper Penticton Creek watershed by the research staff with the Southern Interior Forest Region and reported in Extension Note 676, as well as known channel conditions. Based on the results reported in the extension note, an ECA of 73% would increase the 50-year peak flow by approximately 34% for the SSZ that would represent a high peak flow hazard. Table 5 summarizes the ECAs for Tolko’s past harvesting and for the areas with pine leading within the snow sensitive zone. The area of mature pine is the actual combined areas for polygons with mature pine >40%. The associated percentage value has a 50% reduction factor applied to compensate for the standing timber plus any secondary structure. The data in Table 5 has been extracted from Figures 1 and 3. To appreciate the potential hydrologic impacts of salvage harvesting, if for example 50% of the area of mature pine in the SSZ was salvaged in the North Powers sub-basin, the post harvesting ECA would increase to approximately 59%. This ECA could result in the 50-year peak flow increasing by ~28% that would result in the peak flow hazard increasing to high. For the West Powers sub-basin the ECA would increase to approximately 52% and the 50-year peak flow would increase by approximately 24% that would increase the peak flow hazard rating to high for this sub-basin. In both sub-basins there is storage reservoirs that would provide some attenuation of the peak flows as well. The impact of storing some of the runoff could reduce the increase in peak flow from the loss of the pine above the reservoirs on the flows downstream.

6 Extension Note 67, Schnorbus et al, Ministry of Forests, Forest Sciences Program, 2004


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Forest Cover Distribution in Watershed - Above, Retained Data

21%

11%

2%

4%

5%

46%

11%

<40%>70%40-50%51-60%61-70%LoggedNon-Pine

Table 4. Distribution of Mature Lodgepole Pine in the West Powers Sub-basin

BAND PL_BAND Gross Net Area <40 420.8 0.0>70 221.8 207.1

40-50 46.2 17.251-60 78.4 31.361-70 98.4 59.0Log 928.6 851.5

Above

No Pine 221.0 0.0<40 719.6 0.0>70 309.5 297.0

40-50 112.6 45.051-60 95.9 38.461-70 20.6 12.4Log 1106.2 972.2

Below

No Pine 710.1 0.0

Figure 3. Distribution of Mature Pine in West Powers Sub-basin

Above Only Range Gross %of Total <40% 420.8 20.9>70% 221.8 11.0

40-50% 46.2 2.351-60% 78.4 3.961-70% 98.4 4.9Logged 928.6 46.1

Non-Pine 221.0 11.0 2,015.0 100.0


544-004/26106/January 2008 Page 9 of 12

Figure 4. Distribution of Mature Pine in West Powers Sub-basin

Above & Below Range Gross %of Total <40% 1,140.3 22.4>70% 531.3 10.4

40-50% 158.7 3.151-60% 174.3 3.461-70% 119.0 2.3Logged 2,034.8 40.0

Non-Pine 931.1 18.3 5,089.4 100.0

Forest Cover Distribution in Watershed - Total, Retained Data

23%

10%

3%

3%

2%41%

18%

<40%>70%40-50%51-60%61-70%LoggedNon-Pine


544-004/26106/January 2008 Page 10 of 12

Table 5. ECA for Past Harvesting and for Loss of Mature Pine

Drainage Area above snowline

(ha)

Current ECA above

snowline1 (ha)/(%)

Effective ECA due to Pine Mortality2

(Gross Area) (ha)/(%)

Combined ECA

(%)

North Powers sub-basin 1,750.3 577.6/33.0

596.4/17.0

50.0

West Powers sub-basin 2,709.1 631.2/23.3 1,033.7/19.1 42.4

1. ECA includes only past harvesting. 2. The area value here is the gross area of all polygons with mature pine >40% only and the % value is based on

a 50% reduction of the area to account for the hydrologic effects of a mixed stand + the standing dead pine + secondary structure.

2.4 Hydrologic Impacts of Proposed Retention Plan Assumptions: The following assumptions have been made when considering the hydrologic impacts of the proposed retention plan:

1. Grey attack stands have a similar impact on the hydrology as a clear-cut with regards

to snow accumulation and rates of melt. This differs from the approach used in section 2.3 and is the result of preliminary research for the Okanagan in 2007.l

2. That the guidance in the 1999 IWAP Guidebook (Appendix 2) regarding the ECA of partial cuts is a reasonable approach to represent the hydrologic value of non-pine species in a pine leading stand >40% mature pine.

3. That regenerating stands have achieved full hydrologic recovery with regards to snow accumulation at a height of 12 m.

4. Extension Note 67 (Figure 2, page 3) should only be considered as a general guide to illustrate the potential impacts of harvesting and loss of forest cover on peak flows.

Tolko has completed a retention plan for the Powers Creek sub-basins that is summarized on the Powers Creek Retention Plan (Appendix A – Map 2). For additional information the reader is referred to the Powers Creek Retention Plan available from Tolko. This portion of the hydrologic review focuses on the impact of the areas proposed for harvesting combined with those areas of pine that will not be harvested and compares the results to the loss of the pine with no harvesting summarized in section 2.3. Detailed summaries of the retention plan are provided in Appendix B. Table 6 summarizes the proposed salvage harvesting plan illustrating what the ECA would be for the areas proposed to be harvested plus past harvesting but excluding the pine that will die but will not be harvested. It also summarizes the ECA considering all past and proposed harvesting as well as the pine that will die but not be salvaged.

It is apparent from Table 6 is that for the SSZ, in the North Powers sub-basin there are ~ 507 ha of mature pine and for the West Powers sub-basin there are ~810 ha of mature pine (column 4 minus column 3). It is proposed to salvage ~222 ha or ~44% of the stands in North Powers and 695 ha or ~86% of the stands in West Powers (column 5 minus column 3). The final ECA for the SSZ in North Powers after harvesting is estimated to be


544-004/26106/January 2008 Page 11 of 12

~68% as compared to an ECA of 63% if there was no salvage logging, and West Powers it would be ~61% versus 53% if there was no salvaging (column 6 vs. 4). What is evident from the recovery data for North Powers is that the although the initial ECA for the log scenario is 6% greater than for the no log scenario (68% vs. 62%), at the end of 30 years the recovery for the log scenario has declined to 28% whereas the recovery for the no log scenario is 33%. For West Powers the log and plant scenario is initially 8% higher than the no log scenario (61% vs. 53%), in 30 years it has recovered to 17% versus 32% for the no log option. The 30-year hydrologic recovery curves are provided in Appendix C.

For both sub-basins there is a significant area of mature pine forest in North Powers the stands with mature pine >40% account for ~63% of the remaining unlogged area and for West Powers 42% of the unlogged stands have mature pine >40%. The difference between the two options is that for the no log option the ECA will increase gradually over several years as the pine dies. However where there is salvage harvesting the ECA increases for the area logged as soon as the logging is completed. Regardless of the scenario the peak flow hazard will be high. The benefit of the logging and planting is that the hydrologic recover occurs more quickly than for areas left to regenerate naturally, and this reduces the peak flow hazard sooner.

Table 6. ECA Comparison at December 31, 2006 for no beetle, loss of all mature pine, and

proposed retention plan for the Snow Sensitive Zone

1 Basin

2 Area

Above Snowline

(ha)

3 ECA

assuming no beetle (ha%)

4

ECA Assuming all

Mature Pl Dies

5 ECA For

Proposed Harvesting

(ha/%)

6 ECA

For Retention Plan

(ha/%)

North Powers

Creek sub-basin

1,750.3

577.6 33.0

1,085.2 63.0

799.9 45.7

1,185.9

67.8

West Powers

Creek sub-basin

2,709.1

631.2 23.3

1,440.9

53.2

1,326.4

49.0

1,642.3

60.6

3. CONCLUSIONS

- The current peak flow hazard for the snow sensitive zone (as of December 31, 2006), assuming that there were no beetle impacts, is estimated to be moderate for the North Powers Creek sub-basin and low for the West Powers sub-basin based on the recovery of past harvesting.

- The peak flow hazard for the snow sensitive zone if all the mature pine was to die would increase to high for both sub-basins where the projected increase in the 50-year peak flows may be in the range of 20-25%.

- The proposed salvage harvesting would increase the ECA for the snow sensitive zone in the North Powers sub-basin to ~68% from 62% if there was no salvage harvesting and to ~61% from 53% for West Powers. The increase in ECA for the harvesting scenario is


544-004/26106/January 2008 Page 12 of 12

- due to the loss of non-pine species in the logged blocks. The peak flow hazards associated with the proposed harvesting would remain the same (high) as for the loss of all mature pine scenario.

- The retention plan was revised by Tolko to focus on stands with pine >70% with clear-cut salvage harvesting focused on stands with >50% stand damage.

- Areas that are harvested and replanted would recover faster than areas left to natural regeneration. For North Powers at the end of 30 years the ECA would be ~28% for the combined areas salvaged + past logging versus 33% if there was no salvage logging suggesting that for this sub-basin there are limited benefits from harvesting and planting. However for the West Powers sub-basin the ECA in 30 years would have declined to ~17% versus 32% indicating a positive benefit from harvesting and planting.

4. RECOMMENDATIONS

- Based on the comparison of the hydrologic impacts on peak flows of the proposed retention plan versus no salvage logging, it is recommended that the proposed retention plan proceed for the West Powers sub-basin since the potential benefits to reducing peak flow impacts and water quality impacts that will occur from associated sediment transport over the 30-year recovery period are significantly better for the proposed retention plan than if there was no salvage logging.

- Additional care and attention needs to given to the design and layout of new roads and skid trails to minimize disturbance to the natural drainage patterns and sediment transport.

- New roads required for salvage logging, with the exception of permanent mainline roads, should be constructed as temporary roads and rehabilitated as soon as practical following harvesting and returned to productive forest.

- Stream crossings capacities on existing roads downstream from areas with significant loss of forest cover from the beetle should be reviewed to confirm that the peak flow capacity will be adequate to safely convey anticipated increased peak flows. Where structures are undersized they should be replaced with appropriately sized structures.

- If salvage harvesting is considered within the lakeshore management zone or buffers where the pine component is >70%, the risks to all resources must be considered and a decision made based on balancing these risks.

Original signed by: D.A. Dobson, PEng, Project Engineer Original signed by: Reviewed by: M.E. Noseworthy, P.Geo, Eng.L This page revised February 12, 2008.


544-004/26106/January 2008

Appendix A

Watershed Maps

Okanagan Lake

File:544-004 Project:26106Phase1.mxd

Boundaries

H40

Sub-basin

Watershed

Current ECA

0% (<3m)

25% (3-<5m)

50% (5-<7m)

75% (7-<9m)

90% (>9-<12m)

Immature (>12m <80 Years)

Pine >=40%

Forest Cover

Non Pine

lake

wetland

creeks_a

Water

Powers CreekRetention Plan

Phase 1

�Projection: BC Albers

Datum: NAD 83

Scale: 1:100,000

0 1 2 30.5

kilometre

Okanagan Lake

File:544-004 Project:26106Phase2.mxd

Powers CreekRetention Plan

Phase 2

µProjection: BC Albers

Datum: NAD 83

Scale: 1:100,000

0 1 2 30.5

kilometre

Boundaries

H40

Sub-basin

Watershed

Current ECA

0% (<3m)

25% (3-<5m)

50% (5-<7m)

75% (7-<9m)

90% (>9-<12m)

Immature (>12m <80 Years)

Pine >=40%

Forest Cover

Non Pine

Prop Harv/Pine >=40%

Proposed Harvest

Water

Lake

Wetland

Stream


544-004/26106/January 2008

Appendix B

Data Summaries

Region:

Retained Data:BASIN BAND PL_BAND Gross Net Area RET_FERGUS Plot 1 Plot 2Powers Creek North Powers Sub-basin<40 186.5 0.0 Ret

>70 341.1 339.0 Ret Range Gross %of Total Gross %of Total40-50 27.3 10.9 Ret <40% 186.5 12.2% 496.2 16.2%51-60 0.0 0.0 Ret >70% 341.1 22.3% 811.6 26.5%61-70 51.6 36.1 Ret 40-50% 27.3 1.8% 68.9 2.3%Log 856.3 824.8 Ret 51-60% 0.0 0.0% 11.9 0.4%No Pine 64.4 0.0 Ret 61-70% 51.6 3.4% 66.3 2.2%<40 309.7 0.0 Ret Logged 856.3 56.1% 1,243.7 40.6%>70 470.5 452.0 Ret Non-Pine 64.4 4.2% 362.8 11.8%40-50 41.6 16.7 Ret 1,527.3 3,061.551-60 11.9 4.7 Ret61-70 14.8 9.0 RetLog 387.4 378.3 RetNo Pine 298.4 0.0 Ret

Proposed Logging Data:BASIN BAND PL_BAND Gross Net Area RET_FERGUS Plot 3 Plot 4Powers Creek North Powers Sub-basin<40 45.9 45.9 Prop

>70 69.4 69.4 Prop Range Gross %of Total Gross %of Total40-50 13.9 13.9 Prop <40% 45.9 20.6% 60.9 19.4%51-60 14.6 14.6 Prop >70% 69.4 31.1% 132.4 42.2%61-70 78.5 78.5 Prop 40-50% 13.9 6.2% 17.1 5.5%Log 0.8 0.8 Prop 51-60% 14.6 6.5% 21.8 7.0%No Pine 0.0 0.0 Prop 61-70% 78.5 35.2% 79.8 25.4%<40 15.0 15.0 Prop Logged 0.8 0.4% 0.8 0.3%>70 63.1 63.1 Prop Non-Pine 0.0 0.0% 0.8 0.3%40-50 3.2 3.2 Prop 223.0 313.651-60 7.2 7.2 Prop61-70 1.2 1.2 PropLog 0.0 0.0 PropNo Pine 0.8 0.8 Prop

Powers Creek North Powers Sub-basin

Above

Below

Above Only

Above

Below

Above Only Above & Below

Above & Below

Region:

Retained Data:BASIN BAND PL_BAND Gross Net Area RET_FERGUS Plot 1 Plot 2Powers Creek West Powers Sub-basin<40 420.8 0.0 Ret

>70 221.8 207.1 Ret Range Gross %of Total Gross %of Total40-50 46.2 17.2 Ret <40% 420.8 20.9% 1,140.3 22.4%51-60 78.4 31.3 Ret >70% 221.8 11.0% 531.3 10.4%61-70 98.4 59.0 Ret 40-50% 46.2 2.3% 158.7 3.1%Log 928.6 851.5 Ret 51-60% 78.4 3.9% 174.3 3.4%No Pine 221.0 0.0 Ret 61-70% 98.4 4.9% 119.0 2.3%<40 719.6 0.0 Ret Logged 928.6 46.1% 2,034.8 40.0%>70 309.5 297.0 Ret Non-Pine 221.0 11.0% 931.1 18.3%40-50 112.6 45.0 Ret 2,015.0 5,089.451-60 95.9 38.4 Ret61-70 20.6 12.4 RetLog 1106.2 972.2 RetNo Pine 710.1 0.0 Ret

Proposed Logging Data:BASIN BAND PL_BAND Gross Net Area RET_FERGUS Plot 3 Plot 4Powers Creek West Powers Sub-basin<40 84.1 84.1 Prop

>70 461.1 461.1 Prop Range Gross %of Total Gross %of Total40-50 31.2 31.2 Prop <40% 84.1 12.1% 149.3 13.8%51-60 35.5 35.5 Prop >70% 461.1 66.4% 717.2 66.2%61-70 61.3 61.3 Prop 40-50% 31.2 4.5% 33.9 3.1%Log 0.0 0.0 Prop 51-60% 35.5 5.1% 60.8 5.6%No Pine 20.7 20.7 Prop 61-70% 61.3 8.8% 71.2 6.6%<40 65.2 65.2 Prop Logged 0.0 0.0% 0.0 0.0%>70 256.1 256.1 Prop Non-Pine 20.7 3.0% 50.2 4.6%40-50 2.7 2.7 Prop 693.9 1,082.651-60 25.2 25.2 Prop61-70 9.9 9.9 PropLog 0.0 0.0 PropNo Pine 29.5 29.5 Prop

Below

Above Only Above & Below

Above & Below

Powers Creek West Powers Sub-basin

Above

Below

Above Only

Above

Watershed Report Card for Powers Creek 2006*

Basin Gross Area

(ha)

Total

Harvested

Area

ha

%

ECA

ha

%

ECA

below

Snowline

ha

%

Area

Above

Snowline

ha

ECA

Above

Snowline

ha

%

North Powers 3,375.2 1,203.8

35.7

795.7

23.6

218.1

13.4

1,750.3 577.6

33.0

West Powers 6,172.1 1,823.7

29.5

1,169.5

18.9

538.4

15.5

2,709.1 631.2

23.3

Wednesday, December 27, 2006 Page 1 of 1

* Includes all blocks cut or projected to be cut in 2006

Watershed Report Card for Powers Creek 2006FSP*

Basin Gross

Area (ha)

Total

Harvested

Area

ha

%

ECA

ha

%

ECA

below

Snowline

ha

%

Area

Above

Snowline

ha

ECA

Above

Snowline

ha

%

North Powers 3,375.2 1,516.7

44.9

1,108.6

32.8

308.7

19.0

1,750.3 799.9

45.7

West Powers 6,172.1 2,916.2

47.2

2,262.0

36.6

935.6

27.0

2,709.1 1,326.4

49.0


* Includes all blocks cut or projected to be cut in 2006 and proposed harvest calculated to end 2006

Watershed Report Card for Powers Creek

Total Pine Mortality*Basin Gross Area

(ha)

Total

Harvested

Area

ha

%

ECA

ha

%

ECA

below

Snowline

ha

%

Area

Above

Snowline

ha

ECA

Above

Snowline

ha

%

North Powers 3,375.2 2,246.4

66.6

1,838.3

54.5

753.1

46.4

1,750.3 1,085.2

62.0

West Powers 6,172.1 3,283.0

53.2

2,628.8

42.6

1,187.9

34.3

2,709.1 1,440.9

53.2


* Includes all blocks cut or projected to be cut before end 2006 and loss of Pine, calculated to end 2006

Watershed Report Card for Powers Creek

2006 Retention Plan*Basin Gross

Area (ha)

Total

Harvested

Area

ha

%

ECA

ha

%

ECA

below

Snowline

ha

%

Area

Above

Snowline

ha

ECA

Above

Snowline

ha

%

North Powers 3,375.2 1,549.4

45.9

1,979.5

58.6

793.6

48.8

1,750.3 1,185.9

67.8

West Powers 6,172.1 2,976.0

48.2

2,970.7

48.1

1,328.4

38.4

2,709.1 1,642.3

60.6


* Includes all blocks cut or projected to be cut before end 2006, proposed harvest and loss of Pine calculated to end 2006


544-004/26106/January 2008

Appendix C

30-Year Hydrologic Recovery Tables

Note: The steps in the salvage harvest + replant curve after 17, 22, and 28 years indicate milestones in regenerating stand height, i.e. 3, 5, and 7 metre

North Powers Above SSZ ECA Recovery

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

Years

% E

CA

Salvage Harvest + Replant

No Salvage Harvesting

Note: The steps in the salvage harvest + replant curve after 17, 22, and 26 years indicate milestones in regenerating stand height, i.e. 3, 5, and 7 metre

West Powers Above SSZ ECA Recovery

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

Years

% E

CA

Salvage Harvest + Replant

No Salvage Harvesting

powers creek c watershed - british...

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