Phosphorous Loadingin the Blackstone Watershed

Where does it come fromAnd

What can we do about it?

Blackstone River User’s Conference September 18, 2012

Peter Coffin, Coordinator, Blackstone River Coalition

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MA MADEP CWM HSPF

LU Code Description Description P P P

3 Forest Forest 0.095 0.04 0.10

10 Res Multi Multi-family Residential 3.09 1.97

11 Res High Den High Density Residential (< 0.25 acre lots) 2.41 0.26 1.71

13 Res Low Den Low Density Residential (> 0.5 acre lots) 1.57 0.32 0.94

15 Commercial General Urban, Shopping Center 1.69 1.08

17 Urban Open Parks, Cemeteries, Undeveloped Open Land 0.81 0.61

18 Transport Airports, Docks, Divided Highways, Freight, Railroads 2.72 1.32

Regional and model export coefficient comparison for phosphorus in lbs/acre/year

Land Use Code* Land Use Pervious Impervious

1 Cropland 0.236 0.9912 Pasture 0.236 0.9913 Forest 0.061 0.134 Non-Forested Wetland 0 0

5 Mining 1.08 1.9676 Open Land 0.867 0.8677 Participation Recreation 0.236 1.32

8 Spectator Recreation 0.256 2.8399 Water-Based Recreation 0 010 Multi-Family Residential 0.256 2.83911 High Density Residential 0.256 2.83912 Medium Density Residential 0.256 1.68813 Low Density Residential 0.256 1.688

14 Saltwater Wetland 0 015 Commercial 1.08 1.3216 Industrial 1.08 1.3217 Transitional 0.256 1.68818 Transportation 1.08 1.3219 Waste Disposal 1.08 1.3220 Water 0 023 Cranberry bog 0 024 Powerline/Utility 0.236 0.99125 Saltwater Sandy Beach 0 0

26 Golf Course 0.256 1.688

29 Marina 0 031 Urban Public/Institutional 0.331 2.83934 Cemetery 0.236 0.99135 Orchard 0.061 0.1336 Nursery 0.256 1.68837 Forested Wetland 0 038 Very Low Density Residential 0.256 1.688

39 Junkyard 1.08 1.3240 Brushland/Successional 0.236 0.991

Phosphorus Load (lb./ac/year) in Blackstone River Watershed from HSPF Model

Overlay Phosporous Load Map on to Google Earth30 meter pixels highlight Phosphorous Loads

Bioretention and rain gardens use plant and microbes in the practices to treat pollutant loads. These can range in removal efficiency of 30% to 90% (MA DEP).

Water Quality Swale (Image Source: Portland Bureau of Environmental Services)These are vegetated open channels to treat 10-year storms (MADEP). Pollutant removal efficiency is 20% to 90% for phosphorus.