Agenda - Council Work Session - 02/23/2021

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The federal Clean Water Act (CWA) requires states to adopt water quality standards to protect the nation's waters. Water quality standards establish criteria that must be met to support its designated use(s). The criteria differ depending on the waterbody's classification as a wetland, shallow lake, deep lake, or river. Per the CWA, the state of Minnesota must identify and establish priority rankings for impaired waters that do not meet the water quality standards. The list of impaired waters, sometimes called the 303(d) list, is maintained by the MPCA and updated every 2 years. For impaired waterbodies, the CWA requires an assessment that addresses the causes and sources of the impairment. This process is known as a total maximum daily load (TMDL) analysis. A TMDL is a threshold calculation of the amount of a pollutant that a waterbody can receive and still meet water quality standards. A TMDL establishes the pollutant loading capacity for a waterbody and develops an allocation scheme amongst the various contributors, which include point sources, nonpoint sources and natural background, as well as a margin of safety. As a part of the allocation scheme, a waste load allocation (WLA) is developed to determine allowable pollutant loadings from individual point sources (including loads from storm sewer networks in MS4 communities), and a load allocation (LA) establishes allowable pollutant loadings from nonpoint sources and natural background levels in a waterbody. Within the LRRWMO, Cedar Creek, Trott Brook, the Rum River, and the Mississippi River are listed on the 2020 MPCA impaired waters 303(d) list for a variety of impairments (see Table 2-8). Completed TMDLs and associated implementation plans may contain actionable steps for the cities within the LRRWMO to address these impairments. The LRRWMO coordinates with its member cities, ACD, and other partners to identify activities to address these impairments, where appropriate. Current impaired waters listings are available from the MCPA website: tt+ s:// c .st t n s/ _t}r/ n-s+ tas-i it - t rs-list Select state water quality standards for LRRWMO priority waterbodies are presented in Table 2-9. Water quality standards vary according to lake depth and location (the LRRWMO is located in the North Central Hardwood Forest, or NCHF, ego -region and central river nutrient region). Note that the LRRWMO has more stringent water quality goals for priority waterbodies (see Section 4.1) 2-31