Cheever Lake IA 04-UDM-6384

Assessment Comments

Assessment is based on results of water quality, aquatic vegetation, and fish monitoring conducted by the IDNR shallow lakes and wetlands monitoring program from 2007 and 2008 and information from the IDNR Wildlife Bureau.

Basis for Assessment

SUMMARY: The Class B(LW) (aquatic life) uses are assessed (evaluated) as "fully supported."

EXPLANATION:  Results of water quality, fish, and vegetation monitoring from the IDNR wetland monitoring program suggests that the Class B(LW) (aquatic life) uses are "fully supported."   Using the median values from this survey from 2007 and 2008 (approximately 8 samples), Carlson's (1977) trophic state indices for Secchi depth, chlorophyll a, and total phosphorus were 65, 54, and 63, respectively for Cheever Lake.    According to Carlson (1977) the index values for Secchi depth, chlorophyll a, and total phosphorus all place Cheever Lake in the eutrophic category.    These values suggest low levels of chlorophyll a and suspended algae in the water, moderately poor water transparency, and moderately high levels of phosphorus in the water column.   While the median Carlson's TSI score for Secchi depth suggests moderately poor transparency, Cheever Lake is very shallow and in many cases the Secchi disk is visible when it hits the bottom of the lake.   In these cases the Secchi depth is recorded as the depth of the lake, which underestimates the clarity of the lake.   The median total suspended solids concentration was 4 mg/L, which further suggests excellent water clarity at Cheever Lake.   Therefore Cheever Lake is assessed (evaluated) as "fully supported" based on water clarity, low algae levels and low suspended solids levels.    

Additional monitoring of fish and aquatic vegetation populations at Cheever Lake suggest that fish populations and the production of rooted aquatic vegetation are not adversely impacted by levels of algae and turbidity.