Subwatershed Planning TMDLs

Subwatershed Planningin Calvert County Maryland

Prepared for the

1st Annual Choose Clean Water –

Chesapeake Bay Restoration Conference

A Clean‐up for the Bay – What to 

Expect from the Bay TMDLs at the local level

• TMDL effect on the planning process• TMDL integration with WRE of Comp

Plans• Engaging stakeholders• Eventual implementation of pollution

reduction measures

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September 15, 2008

Water Resource Element

A. Analyze long‐term water needs       and supplies

B. Analyze the impact of sewer treatment plants

C. Analyze the impact of stormwater (diffuse sources)

HB 1141: Water Resources

But first of all, where are we?

Calvert CountyWatersheds

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Entire Watershed –Selected Data

Land Use Zoning

Patuxent Tributary Goals

7Maryland Tributary Strategy Patuxent River Basin, Summary Report for 1985-2005 Data, August 2007

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Water Quality:Patuxent River Basin

HB 1141: Water Resources

9Maryland Tributary Strategy Patuxent River Basin, Summary Report for 1985-2005 Data, August 2007

10Maryland Tributary Strategy Patuxent River Basin, Summary Report for 1985-2005 Data, August 2007

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Maryland Tributary Strategy Patuxent River Basin, Summary Report for 1985-2005 Data, August 2007

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Water Quality: Fresh Water Stream Survey

HB 1141: Water Resources

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Maryland Biological Stream Survey 2000-2004 County Results

Riparian Buffers

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Maryland Biological Stream Survey 2000-2004 County Results

Physical Habitat Index

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Maryland Biological Stream Survey 2000-2004 County Results

Nitrate-Nitrogen

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Maryland Biological Stream Survey 2000-2004 County Results

Total Phosphorus

Water Quality: Based on Land Use and Pollutant Loads

HB 1141: Water Resources

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Impervious Surfaces

Most of our subwatersheds have less than 5% impervious surfaces.

Two subwatersheds would be considered ‘urban’ (more than 10% impervious surfaces.)

Forest canopy is 56-58%.

60% is considered good.

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So what can we conclude from the data?

• Our nutrient loads are higher than we want.• Erosion has caused significant stream damage in places.

• There are opportunities for good water quality• Impervious surfaces are still low and forest cover is still high in most watersheds.

HB 1141: Water Resources

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Smart Growth• Priority

Preservation Areas• Priority Funding

Areas• Transition areas

HB 1141: Water Resources

Best Management Practices (BMPs) and Projected Growth -Nitrogen

Total Nitrogen Load

0200,000400,000600,000800,000

1,000,0001,200,000

2007 LU,2002

BMPs

2007 LU,Trib Strat

BMPs

Scenario1 TribStrat

BMPs

Scenario2 TribStrat

BMPs

Lbs/

Yr Total Septic LoadTotal Terrestrial Load

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HB 1141: Water Resources

Best Management Practices (BMPs) and Projected Growth -Phosphorus

Total Phosphorus Load

010,00020,00030,00040,00050,00060,00070,000

2007 LU,2002

BMPs

2007 LU,Trib Strat

BMPs

Scenario1 TribStrat

BMPs

Scenario2 TribStrat

BMPs

Lbs/

Yr

Total Phosphorus Load

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Best Management Practices include: Cover Crops . . . .

Non-structural stormwater

management

Non-structural stormwater

management

HB 1141: Water Resources

Best Management Practices BMPs and Projected Growth –Impervious Cover

Total Impervious Cover

02,0004,0006,0008,000

10,00012,000

2007 LU,2002

BMPs

2007 LU,Trib Strat

BMPs

Scenario1 TribStrat

BMPs

Scenario2 TribStrat

BMPs

Acre

s

Total Impervious Cover

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HB 1141: Water Resources

Best Management Practices BMPs and Projected Growth –Forest and Agriculture

Forest and Agriculture

010,00020,00030,00040,00050,00060,00070,00080,00090,000

2007 LU,2002 BMPs

2007 LU,Trib Strat

BMPs

Scenario 1Trib Strat

BMPs

Scenario 2Trib Strat

BMPs

Acre

s ForestAgriculture

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Proposed Stormwater Actions(diffuse sources)

HB 1141: Water Resources

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•Set water quality goals. •Prepare subwatershed plans.•Continue to monitor water quality.•Include tree ordinances, with tree canopy goals, in all town center ordinances.•Update the stormwater management ordinance.

HB 1141: Water Resources

Include the following:

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By what standards should we measure water quality?

Draft goals for fresh water:

• <0.71 milligrams of nitrogen per liter

• <0.031 milligrams of phosphorus per liter

• <10 TNUs of turbidity

Draft goals for tidal water:

• Chlorophyll <10 micrograms per liter of water

• Secchi Depth measurements > 1 meter

•Oxygen levels: 4 mg/l for deep waters and 6 mg/l for surface waters.

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Draft goals for urban subwatersheds > 10% impervious:

•Maintain swimmable/ fishable water quality;•Improve water clarity by reducing sedimentation;•Restore aquatic diversity in freshwater streams;•Increase groundwater recharge;•Enhance waterfront access.

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Draft goals for rural subwatersheds < 10% impervious:

Achieve the goals of the urban subwatersheds, plus the following:

•Maintain or restore anadromous (fish spawning) streams•Develop and maintain shellfish beds, both sanctuary and open to harvesting.

Subwatershed Master Plans• Build Partnerships • Characterize Subwatershed• Finalize Goals and Identify

Solutions• Design Implementation

Program• Implement Watershed Plans• Measure Progress and make

adjustments.

Mill Creek:

One of two urban subwatersheds in Calvert County

Town Centers:

Stormwater from two town centers flow toward Mill Creek

Zoning

-Town Center-Residential-Employment Center

Land Use

-Commercial-Residential-Public-Undeveloped

Contour Map

The upper reaches of the subwatershed contain steep slopes

Tree Coverage

Approximately 40% of the subwatershed has tree coverage

-Served by Solomons Sewer System-Served by traditional septic systems-Served by nitrogen-removing system

Sewer vs. Septic

Test sites

Annual harbor study and the Lower Restoration Action Strategy

First Five Subwatershed 

Plans

• Hall Creek• Fishing Creek• Parker’s Creek• Gray’s Creek• Mill Creek

Building connections with citizens

We have been:

• Collecting email addresses  at public presentations

• Collecting email addresses  at community meetings

• Notifying citizens of meetings via email• Posting PowerPoints and videos on the web.

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Challenges

• Creating walkable communities while protecting water quality.• Developing mitigation strategies.• Paying for infrastructure needed for smart growth.• Determining the most cost effective tools to achieve nutrient reduction.• What to do first?