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. Building the . Watershed Development & TMDLs . TMDL Implementation . Retrofit Design . MS4 Cooperation . Phosphorus Reductions . Lessons Learned & Retrofit Program Now 2

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New Amsterdam Water Supply

4 5 NYC Population Growth 80,000

60,000

40,000

20,000

0 1650 1750 1800

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First Water Pollution Law in North America?

Prohibited dumping “filth, garbage or dirt” into pond - 1778.

The pond was filled in - 1811.

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Search for a Reliable Water Supply NYC grew from 80,000 to 200,000 between 1800 and 1830

1835 City issued a $2.5M bond to build a dam & aqueduct to NYC

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9 10 High Bridge over the

10 11 1841 –

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NYC Population continues to grow:

1830 – pop. 200,000 1850 – pop. 700,000 1900 – pop. 3,400,000

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East Branch

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West Branch Reservoir

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Amawalk Reservoir

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Bog Brook Reservoir

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20 21 Muscoot & Reservoirs

21 22 Population increase in

Westchester & Putnam Counties increase by 500,000: . 1940 – 590,000 . 2010 – 1,050,000 23

NYC Reservoir TMDLs 1995 - 303d Listed 19 NYC Reservoirs Nutrient Pollution

2000 – 19 TMDLs approved 108 WWTPs to be upgraded WOH in compliance after upgrades EOH req’d reductions beyond WWTP upgrades

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2003: EOH Watershed designated MS4s: Beekman Lewisboro T & V/Pawling Mount Kisco East Fishkill North Castle Kent North Salem Southeast Pound Ridge Carmel Somers Cortlandt Yorktown Patterson Putnam County Brewster Dutchess County Putnam Valley Westchester County Bedford NYSDOT

24 City EOH Watershed 25

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2008 MS4 Permit Heightened Requirements:

MS4s in impaired watersheds are required to submit an approvable plan to construct stormwater retrofits, and a timetable for their implementation.

Q: What is an Approvable Plan?

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Croton Watershed TMDL Implementation Plan 2009 TMDL Load Allocation target = 6,741 kg/yr . Watershed model results: HID land = 2,400 kg/yr . 50% of developed load = 1,200 kg/yr . 50% efficiency for retrofits = 600 kg/yr . A Starting Point…

Phosphorus Reduction Requirement: 600 kg/yr . Over each 5-year MS4 Permit Cycle . Watershed-wide

Subject to Public Review . No comments dissenting (too high or too low) on assigned load values

27 28 EOH MS4 5-year allocations (kg/yr)

Bedford 32.2 Village of Pawling 4.3 Brewster 9.2 Town of Pawling 3.5 Carmel 72.0 Pound Ridge 9.5 Cortlandt 11.6 Putnam Valley 1 Kent 33.6 Somers 50.0 Lewisboro 35.5 Southeast 31.1 Mount Kisco 18.7 Yorktown 54.0 New Castle 25.1 Beekman 1 North Castle 1 East Fishkill 3.2 North Salem 19.1 Dutchess County 3.1 Putnam County 30.9 Westchester County 8.2 Patterson 17.2 NYS DOT 125

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Approvable Retrofit Design 1. What is the phosphorus load?

2. What is the BMP efficiency?

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Phosphorus to be Treated

Phosphorus Load = runoff *concentration • runoff = 90th percentile storm

30 31 Phosphorus Concentrations Impervious: 0.50 mg/l Residential 0.41 mg/l Developed Open Space: 0.30 mg/l Forest: 0.15 mg/l

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Retrofit Efficiencies Wet Extended Detention Pond 55% Bioretention 65% Dry Swale 50% Sand Filter 60% Organic Filter 60% Shallow Wetland 43%

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Retrofit Sizing Design per NYS Stormwater Design Manual • treat 90th% ~1.3” Storm • Smaller retrofits get partial credit

Hydrodynamic Separators • Treat Peak Flow Rate from 90% Storm • Smaller retrofits get partial credit

Channel Stabilization • Calculate eroded volume of soil • 100% of phosphorus in soil is credited 34 Regional MS4 Group

. Group of MS4s, aka Regional Stormwater Entity (RSE) to submit retrofit plan

. 19 Municipalities across three Counties worked together

. Individual MS4s compliant if RSE meets combined load

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East of Hudson Watershed Corporation

Two full-time Engineering staff now manage over 200 projects: . design . DEC approval . bid process . contract award . construction . project certification 36

Funding the Projects

Year 1-5 Funding: • $20 million NYC + $20 million Putnam and Westchester Counties WQ money

• O&M paid for by MS4 Municipalities

Additional Funding: WQIP Grant Program Prioritizes MS4-required Retrofits 37

Extended Detention Pond

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Pocket Pond

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Wet Pond

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Extended Detention Shallow Wetland

40 41 Micropool Detention

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Outfall Stabilization

42 Bioretention 43

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Extended Detention Pond

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Channel Stabilization

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Pervious Pavers

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22 MS4s – 3 Counties 48

200+ stormwater retrofit projects 49

Phosphorus Reductions: 600+ kg/yr 50

Future Phosphorus Reduction

EOHWC Year 6-10 Retrofit Plan approved • Over 155 New Retrofit Projects Proposed • Estimated 750+ kg/yr • More Channel Stabilization Projects • More Municipal Property https://nysdec.maps.arcgis.com/home/index.html 51

MS4 Retrofit Program 2018 and beyond

https://nysdec.maps.arcgis.com/home/index.html 52

Thank You!

Robert Capowski [email protected]

Ken Kosinski Chief, NYC Watershed Section [email protected]

Bureau of Water Resource Management