2020 MS4 General Permit Section 22 Discharges to Impaired Waters with a USEPA-Approved TMDL that includes an Applicable WLA 2020 MS4 General Permit Section 22 Discharges to Impaired Waters with a USEPA-Approved TMDL that includes an Applicable WLA

Section 22 Discharges to Impaired Waters with a USEPA-Approved TMDL that includes an Applicable WLA

22.1

Discharges to Impaired Waters with a USEPA-Approved TMDL that Includes an Applicable WLA. [Minn. R. 7090]

22.2

If the permittee has an applicable WLA not being met for oxygen demand, nitrate, TSS, or TP, the permittee must provide a summary of the permittee's progress toward achieving those applicable WLAs with the annual report. The summary must include the following information:

a. a list of all BMPs applied towards achieving applicable WLAs for oxygen demand, nitrate, TSS, and TP;

b. the implementation status of BMPs included in the compliance schedule at the time of final application submittal; and

c. an updated estimate of cumulative TSS and TP load reductions. [Minn. R. 7090]

22.3

If the permittee has an applicable WLA where a reduction in pollutant loading is required for bacteria, the permittee must maintain a written or mapped inventory of potential areas and sources of bacteria (e.g., dense populations of waterfowl or other bird, dog parks). [Minn. R. 7090]

22.4

If the permittee has an applicable WLA where a reduction in pollutant loading is required for bacteria, the permittee must maintain a written plan to prioritize reduction activities to address the areas and sources identified in the inventory in item 22.3. The written plan must include BMPs the permittee will implement over the permit term, which may include, but is not limited to:

a. water quality monitoring to determine areas of high bacteria loading;

b. installation of pet waste pick-up bags in parks and open spaces;

c. elimination of over-spray irrigation that may occur at permittee owned areas;

d. removal of organic matter via street sweeping;

e. implementation of infiltration structural stormwater BMPs; or

f. management of areas that attract dense populations of waterfowl (e.g., riparian plantings). [Minn. R. 7090]

22.5

If the permittee has an applicable WLA where a reduction in pollutant loading is required for chloride, the permittee must document the amount of deicer applied each winter maintenance season to all permittee owned/operated surfaces. [Minn. R. 7090]

22.6

If the permittee has an applicable WLA where a reduction in pollutant loading is required for chloride, each calendar year the permittee must conduct an assessment of the permittee's winter maintenance operations to reduce the amount of deicing salt applied to permittee owned/operated surfaces and determine current and future opportunities to improve BMPs. The permittee may use the Agency's Smart Salting Assessment Tool or other available resources and methods to complete this assessment. The permittee must document the assessment. The assessment may include, but is not limited to:

a. operational changes such as pre-wetting, pre-treating the salt stockpile, increasing plowing prior to deicing, monitoring of road surface temperature, etc.;

b. implementation of new or modified equipment providing pre-wetting, or other capability for minimizing salt use;

c. regular calibration of equipment;

d. optimizing mechanical removal to reduce use of deicers; or

e. designation of no salt and/or low salt zones. [Minn. R. 7090]

22.7

If the permittee has an applicable WLA where a reduction in pollutant loading is required for temperature (i.e., City of Duluth, City of Hermantown, City of Rice Lake, City of Stillwater, MnDOT Outstate, St. Louis County, University of Minnesota - Duluth, and Lake Superior College), the permittee must maintain a written plan that identifies specific activities the permittee will implement to reduce thermal loading during the permit term. The written plan may include, but is not limited to:

a. implementation of infiltration BMPs such as bioinfiltration practices;

b. disconnection and/or reduction of impervious surfaces;

c. retrofitting existing structural stormwater BMPs ; or

d. improvement of riparian vegetation. [Minn. R. 7090]