No Net Increase in Pollutants of Concern to Impaired Waters from Urban Runoff

Many of the MS4s in the Syracuse Urbanized Area (SUA) are subject to an additional requirement to ensure “No Net Increase” in Pollutants of Concern to certain impaired waters from their sewershed systems.  The MS4 Permit, GP-0-15-003, contains the following language concerning this requirement:

Part III. B. Impaired Waters:

1. Impaired Waters Without Watershed Improvement Strategies or Future TMDLs

“If a small MS4 discharges a stormwater pollutant of concern (POC) to an impaired water listed in Appendix 2, the covered entity must ensure no net increase in its discharge of the listed POC to that water.  By January 8, 2013, covered entities must assess potential sources of discharge of stormwater POC(s), identify potential stormwater pollutant reduction measures, and evaluate their progress in addressing the POC(S)…  Covered entities must evaluate their SWMP with respect to the MS4's effectiveness in ensuring there is no net increase discharge of stormwater POC(s) to the impaired waters for storm sewersheds that have undergone non-negligible changes such as changes to land use and impervious cover greater than one acre, or stormwater management practices during the time the MS4 has been covered by this SPDES general permit. This assessment shall be conducted for the portions of the small MS4 storm sewershed that discharge to the listed waters… 

If the modeling shows increases in loading of the POC, the SWMP must be modified to reduce the loading to meet the no net increase requirement.  The subsequent annual reports must contain an assessment of priority stormwater problems, potential management practices that are effective for reduction of stormwater POC(s), and document a gross estimate of the extent and cost of the potential improvements.”

The following is a listing of the waters contained in the above-referenced Appendix 2 of the permit that affect the SUA, along with the pollutants of concern for which they are impaired by urban runoff:

The following municipalities, because their sewersheds discharge directly to one or more of the affected waters listed above, are subject to this requirement:

• Baldwinsville Village
• Camillus Town
• Camillus Village
• Cicero Town
• Clay Town
• DeWitt Town
• East Syracuse Village
• Fayetteville Village
• Geddes Town
• LaFayette Town
• Liverpool Village
• Lysander Town
• Manlius Town
• Manlius Village
• Marcellus Town
• Minoa Village
• North Syracuse Village
• Onondaga County
• Onondaga Town
• Pompey Town
• Salina Town
• Solvay Village
• Syracuse City
• Van Buren Town

CNY RPDB, in cooperation with C&S Engineers, performed a baseline assessment comparing land use and stormwater management practices for all affected MS4s between 2008 and 2011 for all affected MS4s.  A report by C&S Engineers summarizing the study can be accessed here: Pollutant of Concern: Modeling in the Syracuse Urbanized Area Using the Watershed Treatment Model (WTM) FINAL Report  (0.99 MB) .