The Watershed The Watershed Treatment ModelTreatment Model

Chesapeake Bay Chesapeake Bay Science and Science and

Technical Advisory Technical Advisory Committee (STAC) Committee (STAC)

Annapolis, MDAnnapolis, MDJune 7, 2011June 7, 2011

Deb CaracoDeb CaracoCenter for Center for Watershed Watershed ProtectionProtection

dsc@cwp.orgdsc@cwp.orgwww.cwp.orgwww.cwp.org

About the Center for About the Center for Watershed ProtectionWatershed Protection

Non-profit 501(c)3, non-advocacy organizationNon-profit 501(c)3, non-advocacy organization

Work with watershed groups, local, state, and Work with watershed groups, local, state, and federal governmentsfederal governments

Provide tools communities need to protect streams, Provide tools communities need to protect streams, lakes, and riverslakes, and rivers

Over 20 staff in MD, VA, NYOver 20 staff in MD, VA, NY

www.cwp.orgwww.cwp.org

www.awsps.orgwww.awsps.org

OverviewOverview

Description of the Watershed Description of the Watershed Treatment ModelTreatment Model Model OverviewModel Overview Some DetailsSome Details Recent UpdatesRecent Updates

Integration of Local Watershed Integration of Local Watershed Planning Tools into the Chesapeake Planning Tools into the Chesapeake Bay ProgramBay Program

What is the WTM?What is the WTM?

A simple, A simple, spreadsheet model spreadsheet model for the rapid for the rapid assessment of assessment of watershed treatment watershed treatment optionsoptions

Annual outputAnnual output Pollutant loads (lbs/acre)Pollutant loads (lbs/acre) Bacteria Loads (MPN/yr)Bacteria Loads (MPN/yr) Runoff Volume (acre-ft/yr)Runoff Volume (acre-ft/yr)

WTM ApplicationsWTM Applications

Stormwater Program AssessmentStormwater Program Assessment Stormwater Retrofit RankingStormwater Retrofit Ranking Source Water AssessmentSource Water Assessment Determine Progress on Load Determine Progress on Load

Reductions*Reductions* TMDLsTMDLs MS4 AccountingMS4 Accounting

WTM TerminologyWTM Terminology

Primary SourcesPrimary Sources Secondary SourcesSecondary Sources Management PracticesManagement Practices Discount FactorsDiscount Factors

WTMABCs

Primary SourcesPrimary Sources

Determined Determined entirely from entirely from land use/coverland use/cover ResidentialResidential Commercial Commercial IndustrialIndustrial ForestForest RuralRural

Watershed Subcatchment SegmentGreen cells need to be completed by the userBlue cells have default or calculated values but may be substitutedGrey cells should generally not be changedPurple Cells Reflect "Bottom Line" Loads or Load Reductions

PRIMARY SOURCES - Land UseWatershed

Area Impervious Turf TN TP TSS FC(Acres) Cover (%) Cover (%) (mg/l) (mg/l) (mg/l) (MPN/100 ml)

Categorty Detailed DescriptionResidential LDR (<1du/acre) 12% 70% 2 0.26 55 20000

MDR (1-4 du/acre) 21% 63% 2 0.26 55 20000HDR (>4 du/acre) 33% 54% 2 0.26 55 20000

Multifamily 44% 45% 2 0.26 55 200000%0%0%0%0%0%

Commercial Commercial 72% 22% 2 0.26 55 200000%0%0%0%

Roadway Roadway 80% 16% 2 0.26 55 200000%0%0%0%

Industrial Industrial 53% 38% 2 0.26 55 200000%0%0%0%

Forest Forest

Rural Rural

Open Water Open WaterActive Construction Active Construction 1 0.2 680 0

Total 0 #DIV/0!

Annual Loading RatesConcentrationsPrimary Sources:Primary Sources:• Residential LandResidential Land• Commercial LandCommercial Land• RoadwaysRoadways• Industrial LandIndustrial Land• ForestForest• Active ConstructionActive Construction• Open WaterOpen Water

Primary Sources:Primary Sources:• Residential LandResidential Land• Commercial LandCommercial Land• RoadwaysRoadways• Industrial LandIndustrial Land• ForestForest• Active ConstructionActive Construction• Open WaterOpen Water

Secondary SourcesSecondary Sources

Cannot be Cannot be calculated solely by calculated solely by land useland use

ExamplesExamples CSOs, SSOsCSOs, SSOs Septic SystemsSeptic Systems Channel ErosionChannel Erosion

Types of Management Types of Management PracticesPractices

Structural: Structural: ponds, swale, LID ponds, swale, LID

etc.etc. Non-Structural: Non-Structural:

street sweeping, street sweeping, downspout downspout disconnect, buffers disconnect, buffers

Programmatic: Programmatic: lawn and pet waste lawn and pet waste

education, etceducation, etc

Discount FactorsDiscount Factors Ideal load reductions can rarely Ideal load reductions can rarely

be achievedbe achieved Lack of spaceLack of space Imperfect practice applicationImperfect practice application Inability of programs to be Inability of programs to be

completely effectivecompletely effective

Discount factors "discount" load Discount factors "discount" load reductions to account for less reductions to account for less than perfect application of than perfect application of practices.practices.

A Few WTM DetailsA Few WTM Details

Model StructureModel Structure Some Data Entry Some Data Entry

Tips and Rules Tips and Rules Ongoing WTM Ongoing WTM

UpdatesUpdates

The (Tasmanian) Devil’s in the Details

Primary Sources

Step 1. Calculate Existing Pollutant Loads

+ Secondary Sources -

Existing Management

Practices= Existing

Loads

Step 2. Apply “Future” Management Practices

FutureManagement

Practices-

Existing Loads =

Loads with Future Management

Practices

Step 3. Account for Future Growth

+ New Development = Loads with

Future Growth

Retrofit Worksheet

Loads with Future Management

Practices

Future Land Use

Stream Restoration Worksheet

Spreadsheet “Tabs”Spreadsheet “Tabs”

Step 1:Step 1:

1a.1a. Primary SourcesPrimary Sources

1b.1b. Secondary SourcesSecondary Sources

1c.1c. Existing Existing Management Management PracticesPractices

1d.1d. Existing Loads]Existing Loads]

Step 2:Step 2:2a.2a. Future Management Future Management

PracticesPractices2b.2b. Retrofit WorksheetRetrofit Worksheet2c. Stream Restoration 2c. Stream Restoration

WorksheetWorksheet2d.2d. Load with Future Load with Future

Management Management PracticesPractices

Step 3:Step 3:3a.3a. Future Land UseFuture Land Use3b.3b. New DevelopmentNew Development3c.3c. Loads With Future Loads With Future

GrowthGrowth

Pet Waste Education

Program in Place? no

Both# of dwelling units 0

Fraction of Households with a Dog 40%Owners who Walk their Dogs (fraction) 50%

Owners who Clean Up (fraction) 60%Fraction willing to change behavior 60%

Awareness of Message (Fraction of Population) 0%

Data Entry: Data Entry: The WTM is Color-Coded.The WTM is Color-Coded.Green (Cells and Tabs) require user inputGreen (Cells and Tabs) require user inputBlue Cells are defaults the user can overrideBlue Cells are defaults the user can overrideGrey Cells should not be modifiedGrey Cells should not be modifiedPurple (Cells and Tabs) represent Final OutputsPurple (Cells and Tabs) represent Final Outputs

Pet Waste Education

Program in Place? yes

Both# of dwelling units Enter Value

Fraction of Households with a Dog 40%Owners who Walk their Dogs (fraction) 50%

Owners who Clean Up (fraction) 60%Fraction willing to change behavior 60%

Awareness of Message (Fraction of Population) Enter Value

Use Local Data if Available

Data Entry: Pay Data Entry: Pay Attention to “Pop Up” Attention to “Pop Up”

GuidanceGuidance

Some Recent UpdatesSome Recent Updates

Additions to the model.Additions to the model. Some sources simplifiedSome sources simplified Additional research to update some Additional research to update some

sources and practices.sources and practices.

Example Addition: Example Addition: Runoff ReductionRunoff Reduction

Land-Use Specific Runoff Coefficients

A Soils 0.95 0.15 0.02 0.02 0.5B Soils 100% 0.95 0.20 0.03 0.03 0.5C Soils 0.95 0.22 0.04 0.04 0.5D Soils 0.95 0.25 0.05 0.05 0.5

Weighted Rv 0.95 0.2 0.03 0.03 0.5

Soil Type Distribution Soil Fraction(%) Forest Rural

Runoff Coefficients

Active ConstructionImpervious Turf

Incorporate runoff coefficients for Incorporate runoff coefficients for various soil-land use combinations.various soil-land use combinations.

Assign Runoff Reduction to various practicesAssign Runoff Reduction to various practicesStructural Stormwater Management Practices

Total Area Impervious Cover RunoffCaptured (Acres) Captured (Acres) Reduction (%)

BMP TypeDry Water Quantity Pond 0%

Dry Extended Detention Pond 0%Wet Pond 0%Wetland 0%Filters 0%

Green Roof 45%Rooftop Disconnection 25%Permeable Pavement 45%Grass (open) Channel 10%

Dry Swale (bioswale, WQ swale) 40%Wet Swale 0%

Raintanks and Cisterns 40%Soil Amendments 50%

Sheetflow to Open Space (excluding riparian buffers) 50%Bioretention with Underdrain 40%

Bioretention Without Underdrain (infiltration design) 40%Infiltration Practices 50%

Example Simplification: Example Simplification: Channel ErosionChannel Erosion

Problem:Problem: Original WTM asked Original WTM asked

for data that we for data that we found was not readily found was not readily available available

Alternative was too Alternative was too simplified.simplified.

Solution:Solution: Offer alternatives to Offer alternatives to

the user.the user. Allow use of other Allow use of other

outside methodsoutside methods

New Research/Update: Turf New Research/Update: Turf ManagementManagement

Original Version:Original Version: Focuses “leachate” only.Focuses “leachate” only. Relies on a few studies.Relies on a few studies. Asks for some data that is Asks for some data that is

not readily available.not readily available. New Version: New Version:

Is backed by an extensive Is backed by an extensive literature surveyliterature survey

Incorporates field Incorporates field observations from observations from watershed assessments.watershed assessments.

Key Considerations for Key Considerations for Integrating Local Integrating Local

Watershed PlanningWatershed Planning

Source: MAST Maryland’s Assessment and Scenario Tool, (MDE, MD DNR, MDP)http://archive.chesapeakebay.net/pubs/calendar/47043_05-09-11_Presentation_1_11266.pdf

Where does Local Modeling Fit in?

Bay Program NeedsBay Program Needs

List of practices for the Chesapeake List of practices for the Chesapeake Bay Watershed Model (the Bay Bay Watershed Model (the Bay Model) from local planning efforts.Model) from local planning efforts.

Local governments need an estimate Local governments need an estimate of the “credit” given in the Bay of the “credit” given in the Bay Model.Model.

MAST, other tools help estimate this MAST, other tools help estimate this aggregation of practices.aggregation of practices.

Some Concerns About Some Concerns About Using “Local” Models (e.g., Using “Local” Models (e.g.,

WTM)WTM) The numbers may or may not line up The numbers may or may not line up

with Bay Program assumptions.with Bay Program assumptions. Is the model “Bay Program Is the model “Bay Program

Sanctioned”Sanctioned” What if the model includes practices What if the model includes practices

that aren’t in the Bay Model?that aren’t in the Bay Model? Do the land use types line up with Do the land use types line up with

the Bay Model?the Bay Model?

Do the Numbers Line Do the Numbers Line Up?Up?

Some key Some key concernsconcerns Are the assumed Are the assumed

efficiencies the efficiencies the same?same?

Are the loading Are the loading rates the same?rates the same?

Do they need to Do they need to be?be?

How much N and P did you say you

got?

WTM: Issues of WTM: Issues of ConsistencyConsistency

Efficiencies of most practices are Efficiencies of most practices are similar to Bay Program data (but similar to Bay Program data (but account for “filtering” versus “runoff account for “filtering” versus “runoff reduction” rather than an reduction” rather than an aggregate).aggregate).

Slightly different mechanism of Slightly different mechanism of calculating loading rates from some calculating loading rates from some sources.sources.

To Ensure Consistency with To Ensure Consistency with the the

CBP ModelCBP Model Ensure that basic Ensure that basic

data (e.g., loading data (e.g., loading rates and rates and efficiencies) are the efficiencies) are the same.same.

Update WTM (or Update WTM (or other local model) as other local model) as Bay Program Bay Program assumptions are assumptions are updated.updated.

What do other local What do other local models offer?models offer?

Other pollutants (beyond TN, Other pollutants (beyond TN, TP, TSS)TP, TSS)

Broader range of practices*Broader range of practices* Assessment of the Assessment of the degree of degree of

implementationimplementation (e.g., “discount (e.g., “discount factors”)factors”)

Ability to predict benefits of Ability to predict benefits of educational, other practices.educational, other practices.

Can Local Efforts Can Local Efforts Identify New Practices?Identify New Practices?

Example: Illicit Example: Illicit Discharge RemovalDischarge Removal Currently not Currently not

accounted for in the accounted for in the Bay Model.Bay Model.

Local modeling Local modeling efforts identify the efforts identify the potentialpotential removal. removal.

Use monitoring data Use monitoring data to actually measure to actually measure pollutant removal.pollutant removal.

Can Local Models Quantify Can Local Models Quantify “Reasonable Assurances”“Reasonable Assurances”

Some key assurances:Some key assurances: Long term maintenance.Long term maintenance. Proper practice sizing Proper practice sizing

and implementation.and implementation. Can we use the Can we use the

discount factors discount factors concept to quantify concept to quantify this?this?

If so, how do we do If so, how do we do this in a consistent this in a consistent manner?manner?

What About Educational/ What About Educational/ Programmatic Practices?Programmatic Practices?

We encourage and We encourage and require education and require education and public education/ public education/ participation.participation.

How do we account for How do we account for the actual results of the the actual results of the program?program?

Local Models can predict Local Models can predict the benefits based on the benefits based on assumed effectiveness.assumed effectiveness.

What follow-up is needed What follow-up is needed to ensure that the to ensure that the benefits are actually benefits are actually achieved?achieved?

SummarySummary

The Watershed Treatment Model (WTM) The Watershed Treatment Model (WTM) is a simple, spreadsheet-based model is a simple, spreadsheet-based model that accounts for a wide range of that accounts for a wide range of practices.practices.

Some details need to be worked out for Some details need to be worked out for any local model to be consistent with the any local model to be consistent with the Bay Watershed Model.Bay Watershed Model.

Local models can potentially inform the Local models can potentially inform the way practices are modeled in the Bay way practices are modeled in the Bay Watershed.Watershed.

Questions?Questions?

Deb CaracoDeb Caraco

Center for Watershed ProtectionCenter for Watershed Protection

607-277-6337607-277-6337

dsc@cwp.orgdsc@cwp.org

www.cwp.orgwww.cwp.org

www.awsps.comwww.awsps.com