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Crediting methods summary

Crediting methods summary. To access documents for each method, see the reference list at this link.
Location Crediting method Pollutants
Chesapeake Bay Watershed (entities subject to Bay TMDL requirements)
  • Reduction efficiency
  • % reduction from existing load
  • Qualifying lane miles -lb/acre reduction
  • Mass load reduction
 TN, TP, TSS
Florida Mass load reduction TN, TP
EPA Region 1 (New Hampshire and Massachusetts MS4 permittees) Mass load reduction with efficiency factors TN (NH only), TP
Massachusetts – stormwater requirements (not linked to MS4 permit) Reduction efficiency - % TSS
Wisconsin
  • Reduction efficiency
  • progress towards % reduction target
  • Reduction efficiency - %
  • TSS, with conversion to TP
  • TP
Washington Ecology – MS4 permittees with TMDL Mass load reduction, effective developed acres reduction TP, sediment
County and City of San Diego and MS4 Co-permittees Performance-based compliance Cu, Zn, Pb, TKN, TP
Orange County and MS4 Co-permittees Reduction efficiency - % Bacteria, sediment
City of Santa Cruz, California Modeled load reduction Sediment
Vermont (Under development)
  • Interim – modeled load reduction
  • Permanent – under development
 TP
North Carolina (Under development) Mass load reduction TN, TP