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Published byFrancine Chambers Modified over 8 years ago
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Presented to: Severn River Association 2008 State of the Severn Anne Arundel County Government Department of Public Works Ron Bowen, P.E. October 21, 2008
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Anne Arundel County Impervious Areas Our “greatest challenge” is restoration of those areas developed in an era when storm water management was non-existent or much less than it is today... Historical Urbanization vs. New Development
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Severn River Watershed Impervious Cover Landcover Acres Impervious Acres Impervious % of Landcover % of Total Impervious Commercial (Private Lands) 1,9711,505 76 %16 % Industrial (Private Lands) 50638175 %4 % Residential (Private Lands) 16,3324,00124 %43 % Gov’t Owned (Public Lands) 10,2192,95629 %32 % Other (Private Lands) 15,3254473 %5 % Total44,3539,29021 %100 %
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EPA/MDE Clean Water Act Listed Impaired Waters Severn River Pollutant Impairments Bacteria – Fecal Coliform for Shellfish Harvesting TMDL issued Biological (combination Benthic/Fish) Nutrients (Total Nitrogen and Total Phosphorous) Sediments Toxics (PCB in Fish Tissue)
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Severn River Watershed Total Nutrient Loads from Stormwater and Septics Total Nitrogen (TN) TN (lbs/yr) - Existing TN (lbs/yr) - Buildout % Increase Total Phosphorous (TP) TP (lbs/yr) - Existing TP (lbs/yr) - Buildout % Increase = 449,629 = 490,257 = 9 % = 25,594 = 27,117 = 6 %
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Severn River Watershed Existing Septic Systems Annual Nitrogen Load Critical Area104,975 lbs/year Non-Tidal Surface Streams112,342 lbs/year All Remaining Areas22,032 lbs/year Total239,349 lbs/year
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Septic Systems within the Severn River Recommended Retrofits
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Best Overall Conditions Worst Overall Conditions City of Annapolis Severn River Watershed Subwatershed Condition Assessment for Restoration
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Severn River Watershed Stream Restoration Challenge 178 miles of total non-tidal streams 25 miles are degraded streams Rated poor to very poor Degraded Streams Stream Reaches
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Severn River Watershed Stormwater Controls Watershed Area Acres Percent % 44,213 -- Managed Area 6,370 14 Managed Public Area Managed Private Area 3,86460 2,506 40 Note: Only 19% of current Stormwater controls provide water quality treatment Management Areas have varying degrees of impervious contribution (Avg 21%)
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