Como Lake TMDL

Como Lake was listed as an impaired water by the Minnesota Pollution Control Agency (MPCA) in the 2002 303(d) list. The impaired use is aquatic recreation, with the stressor identified as "nutrient/ eutrophication biological indicators." In 2002 the Capitol Region Watershed District developed a management plan for Como Lake. The Como Lake Strategic Management Plan (CLSMP) identified important management issues through input from key stakeholder groups, prioritized the issues and associated goals, and identified implementation activities. The CLSMP was used as the basis for this TMDL. The Como Lake watershed is located in the north-central portion of the Capitol Region Watershed District (CRWD), which lies entirely within the North Central Hardwood Forest Ecoregion. Como Lake is located in the City of Saint Paul and the watershed is located within three municipalities in Ramsey County. Phosphorus was identified as the main pollutant causing the impairment. The MN state eutrophication standards for shallow lakes were used to calculate the total maximum daily load (TMDL) for Como Lake. Como Lake is a eutrophic lake, with relatively higher total phosphorus (TP) compared to chlorophyll-a concentrations and transparency. TP growing season means ranged from 100 to 400 μg/L. 2001 was the year with the poorest water quality. The same general pattern exists for chlorophyll-a and Secchi depth. The sources of phosphorus loads to Como Lake are watershed runoff, internal loading, and atmospheric deposition. Phosphorus loads from each of these sources were estimated and used as input into the lake response model, which was used to estimate the assimilative capacity of the lake.