This guidance can be used to assist Municipal Separate Storm Sewer System (MS4) Permittees in completing the MS4 General Stormwater Permit Application and the Commissioner-approved TMDL Annual Reporting Form (TMDL Form). The guidance linked below contains information about baseline years for TMDLs approved prior to the effective date of the MS4 permit that do not explicitly define a baseline year in the TMDL report. Any best management practices (BMPs) or activities implemented by MS4s during or after the baseline year that result in a reduction in pollutant loads to the impaired waterbodies can be considered as progress towards meeting a WLA. The *List of Approved TMDLs with MS4 WLAs (updated November 2019) includes the baseline year identified in the TMDL, or the MPCA recommended baseline year included in the baseline year guidance document below.

Please click here to download the baseline year guidance document: File:TMDLbaselinesMS4.xlsx