Lake Assessment Program - Lake Hendricks, Lincoln County

Lake Hendricks is located at Hendricks, Minnesota in Lincoln County in southwestern Minnesota and Brookings County in South Dakota. The lake is shallow, with a maximum depth of ten feet. The surface area of the lake is 1,634 acres, placing it in the upper five percent of lakes in the state in terms of size (HDNR, 1968). The lake's watershed is relatively large (49 square miles) compared to the surface area of the lake (19:1 ratio) and lies in the middle of the Prairie Coteau, a plateau-like highland. About 80 percent of the watershed is in South Dakota and 20 percent in Minnesota. About 74 and 26 percent of the watershed are in agriculture cropland and rangeland, respectively. These are typical percentages for lakes in this part of the state, the Northern Glaciated Plains ecoregion. Lake Hendricks was sampled during the summer of 1989 by Minnesota Pollution Control Agency (MPCA) staff and citizens from the Lake Hendricks Improvement Association as part of the Lake Assessment Program (LAP). Data was also collected by the South Dakota Department of Water and Natural Resources (SDDVNR). The water quality data collected during this study indicates that Lake Hendricks is hypereutrophic with a mean total phosphorus concentration of 208 ug/1, mean chlorophyll concentration of 31 ug/1 and a mean Secchi transparency of 1. 6 ft. The maximum chlorophyll concentration for the summer was 64.1 ug/1. The total phosphorus concentration is relatively high when compared to representative minimally impacted lakes in the Northern Glaciated Plains (NGP) ecoregion, and the Secchi transparency is subsequently low. Compared to other lakes in the NGP ecoregion, the phosphorus concentration ranks at about the 65th percentile, which means that about 65 percent of lakes in the ecoregion contain lower concentrations of total phosphorus than Lake Hendricks, while about 35 percent of the lakes exhibit higher total phosphorus concentrations,