Future Growth Consideration/Reserve Capacity

New or Expanding Permitted MS4 WLA Transfer Process

Future transfer of watershed runoff loads in this TMDL may be necessary if any of the following scenarios occur within the project watershed boundaries:

  1. New development occurs within a regulated MS4s. Newly developed areas that are not already included in the WLA must be transferred from the LA to the WLA to account for the growth.
  2. One regulated MS4 acquires land from another regulated MS4. Examples include annexation or highway expansions. In these cases, the transfer is the WLA to WLA.
  3. One or more non-regulated MS4s become regulated. If this has not been accounted for in the WLA, then a transfer must occur from the LA.
  4. Expansion of a US Census Bureau Urban Area encompasses new regulated areas for existing permittees. An example is existing state highways that were outside an urban area at the time the TMDL was completed, but are now inside a newly expanded urban area. This will require either a WLA to WLA transfer or a LA to WLA transfer.
  5. A new MS4 or other stormwater-related point source is identified and is covered under a NPDES permit. In this situation, a transfer must occur from the LA.

Load transfers will be based on methods consistent with those used in setting the allocations in this TMDL. In cases where WLA is transferred from or to a regulated MS4, the permittees will be notified of the transfer and have an opportunity to comment.

For more information on the overall process visit the MPCA’s TMDL Policy and Guidance webpage.

New or Expanding Wastewater

During the permit issuance or reissuance process, new and/or expanding wastewater discharges will be evaluated for the potential to cause or contribute to violations of chloride water quality standards. Water Quality Based Effluent Limits (WQBELs) will be developed for facilities whose discharges are found to have a reasonable potential to cause or contribute to excursions above the water quality standards. The WQBELs will be calculated based on low flow conditions, may vary slightly from the TMDL WLAs and will include concentration based effluent limitations.

This page was last edited on 23 November 2022, at 15:56.