INCORPORATING TMDL LOAD REDUCTIONS INTO THE ANCHORAGE, ALASKA, MS4 PERMIT

In order to effectively integrate Total Maximum Daily Loads (TMDLs) into municipal separate storm sewer system (MS4) permits, an appropriate level of precision and specificity about how the TMDL load allocations were derived must be established. Many urban TMDLs can be readily associated with an MS4 or if the Clean Water Act (CWA) section 303(d)-listed waters are located in or near an MS4s by taking the MS4 city and county boundaries and intersecting them with the listed reaches and watersheds. Most existing urban TMDLs and those that are currently being developed can be researched to answer the following questions:Are storm water discharges that are regulated under the National Pollutant Discharge Elimination System (NPDES) partitioned separately from unregulated storm water and nonpoint sources?If they are partitioned separately, are specific sources identified, or are they partitioned simply by category?Is it feasible to determine reasonable estimates of loads for NPDES regulated storm water separately from unregulated sources and nonpoint sources?Are specific best management practices (BMPs) identified in the TMDL?The incorporation of the results of the fecal coliform TMDLs for the urban streams within the Municipality of Anchorage (MOA), Alaska, into the MOA's soon-to-be reissued NPDES MS4 permit presents a case study that illustrates some of these challenges.