Application of the

Watershed Treatment Model for a

Countywide Watershed Implementation Plan in the

Chesapeake BayNick Lindow

Biohabitats, Inc.

Meosotis Curtis and Steve ShofarMontgomery County DEP

September 27, 2011

OverviewI. The New Framework

i. Locationii. Regulationsiii. Restoration

II. History of the Practice

III. Environmental Site Design Approach

IV. Modeling Framework

V. Targeting Strategy

VI. Results and Lessons Learned

Location

• Montgomery County, MD

– 500 sq. miles

– 940,000 people

– About 12% impervious cover

• Second only to Baltimore City within

MD in average people per square mile

• Potomac and Patuxent River

Watersheds

Regulations

• 2010 NPDES Stormwater Permit– Restoration – 20% Retrofit– TMDL Wasteload Allocations– Trash Reduction– Develop Implementation Plans*– Track Progress*

• 2010 MDE Stormwater Manual – requirements for new and re-development have changed – ESD to the MEP

History of the Practice

Pre-1984 Stormwater LawPre-1984 Stormwater Law

1984 Stormwater Law- 2000 Stormwater Manual1984 Stormwater Law- 2000 Stormwater Manual

2010- ESD to the MEP Required2010- ESD to the MEP Required

ESD Approach

History of the Practice

Bacteria?

ESD = 75% Removal

Fecal Coliforms

Fecal Coliforms

E. ColiE. Coli

EnterrococciEnterrococci

Trash?

Modeling Framework

Watershed Treatment Model

BMPs• Performance

Code• Removal

Efficiency

Discount Factors• BMP specific• Treatability

Factor

Pollutant Reduction• Applied to

baseline load

Land Use• EMC

(Urban)• Unit Load

(Non-urban)

Soils & Rainfall• Annual

Runoff Volume

Pollutant Load• Before• treatment

TMDL “Calibration”

• TMDL Onion– Land use discrepancies with Waste Load

Allocations– Differences in Pollutant Sources– Watershed-specific EMCs or loading rates

Bacteria TMDL: Sources

Human12%

Livestock30%

Wildlife26% Wildlife

13%

Pets19%

Montgomery County MS4 

Load32%

Rock Creek Watershed Probable Bacteria Pollution Sources

Strategies

• Structural Management Practices• Habitat Restoration

– Reforestation– Stream Restoration

• Programmatic Practices– Pet Waste Education– Lawn Care Education– Street Sweeping

Targeting Strategy

• Hotspots

Targeting Strategy

• Impervious Surfaces

Targeting Strategy

• County-owned Land

Targeting Strategy

• Private Residential and Non-residential Property

Targeting Strategy

• Riparian Buffer

Targeting Strategy

• Outreach and Education

Bacteria TMDL: Tracking Progress

$- $100 $200 $300 $400 $500 $600 $700 $800 $900

0%10%20%30%40%50%60%70%80%90%

100%

Cos

t (M

illio

n $)

Bac

teria

l Red

uctio

n (%

of B

asel

ine)

Implementation Phase

Bacterial Load Reduction

TMDL WLA Target

Cost

Cost of Restoration

Lessons Learned

• Don’t bite off more than you can chew– Technical and Financial Assistance Required– Local government leadership– Better and more incentives– Third party (e.g., watershed organizations, HOAs,

community groups) support and involvement• Restoration will require more than ESD

– Integration of green infrastructure with stormwatermanagement practices/techniques

– Habitat creation & land conversion– Programmatic Practices & Education

• Human behavior– Increased conservation and preservation ethic