Crediting methods summary
Link to this table

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