Lake Assessment Program - Cedar Lake, Aitkin County

Cedar Lake is located in Aitkin County, near Aitkin, Minnesota. With a surface area of approximately 1,729 acres, it ranks near the 90th percentile in terms of surface area as compared to over 11,000 lakes in Minnesota (less than 10% of MN lakes are larger than Cedar Lake). Cedar Lake has a maximum depth of about 100 feet and a mean depth of about 28 feet. The lake is characterized by numerous bays and in this study distinctions are made between sites in the main basin of the lake as compared to the small southwest basin. The total watershed, at approximately 37 square miles, is moderate-sized compared to the size of the lake (17:1 ratio). Land use in the watershed is composed of about 59 % forest and wetland and 22 % grass and pasture land. The pasture and grass land uses are slightly high as compared to other lake watersheds in this region of the state -- Northern Lakes and Forests (NLF) ecoregion. Cedar Lake was sampled during the summer of 2002 by the Minnesota Pollution Control Agency (MPCA) staff and citizens from the Cedar Lake Conservancy (Association). Water quality data collected during the study at four sites reveal lake-wide summer-mean total phosphorus (TP) concentration of 20 ?g/L, chlorophyll a of 9.6 ?g/L and Secchi transparency of 7.9 feet. All three measures are within or near the range of values exhibited by reference lakes in the NLF ecoregion. Total phosphorus, chlorophyll a and Secchi transparency help to characterize the trophic status of a lake. These measures indicate mesotrophic to mildly eutrophic conditions for Cedar Lake. Other water quality parameters measured are comparable to minimally impacted lakes in the NLF ecoregion. TP and chlorophyll-a concentrations in the southwest basin were slightly higher than concentrations in the main basin. The Association also monitored TP and flow in several tributaries to the lake in 2002. This monitoring showed some differences between some of the watersheds. The aggregate mean TP from all tributary measurements was 55 ?g/L, which is fairly close to the typical range for streams in the NLF ecoregion.