Lake Assessment Program - Long Lake, Watonwan County

Long Lake was sampled during the spring and summer of 1994 as part of the Minnesota Pollution Control Agency's (MPCA) Lake Assessment Program (LAP). Data collected during the study showed that in terms of total phosphorus, chlorophyll-a, Secchi disk transparency, and a number of other parameters, the water quality of Long Lake is better than most lakes in the Western Corn Belt Plains (WCBP) ecoregion. The mean summer concentrations of total phosphorus and chlorophyll-a were 59 and 35 pg/L (pa =micrograms per liter) respectively, and the mean Secchi disk transparency was 1.0 meters (3.2 feet). Based on these values and Carlson's Tmphic Status Index VSI) (Carlson, 1977), which ranges fiom 0 (very oligotrophic) to 100 (hypereutrophic), Long Lake would be considered eutrophic. The average TSI value for Long Lake is 63. Long Lake is considered by the MPCA to be minimally impacted" and was used as a reference lake for the ecoregion. Results from sampling done in 1993 showed results similar to those listed above.
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