Meyers Lake IA 02-CED-463

For the 2016 assessment/listing cycle, the Class A1 (primary contact recreation) uses of Meyers Lake are assessed (monitored) as "partially supported" due to poor water transparency and aesthetically objectionable conditions caused by algae blooms based on information from the ISU lake survey. Using the median values from these surveys from 2010-2014 (approximately 13 samples), Carlson 's (1977) trophic state indices for Secchi depth, chlorophyll a, and total phosphorus were 67, 67, and 71 respectively for Meyers Lake. According to Carlson (1977) the Secchi depth, chlorophyll a, and total phosphorus values all place Meyers Lake in between the Eutrophic and the Hypereutrophic categories. These values suggest high levels of chlorophyll a and suspended algae in the water, poor water transparency, and very high levels of phosphorus in the water column. The data show one violation of the Class A1 criterion for pH in 13 samples.

The level of inorganic suspended solids was moderately high at Meyers Lake, and does suggest that non-algal turbidity may contribute to the impairment at this lake. The median level of inorganic suspended solids in Meyers Lake (4.33 mg/L) was ranked 83rd among the 138 lakes by the ISU lake survey.

Data from the 2010-2014 ISU lake survey suggest a moderate population of cyanobacteria exists at Meyers Lake. These data show that cyanobacteria comprised 71% of the phytoplankton wet mass at this lake. The median cyanobacteria wet mass (19.5 mg/L) was ranked 63rd of the 138 lakes sampled.

The Class B(LW) (aquatic life) uses are assessed (evaluated) as “partially supported” due to fish kills that occurred at Meyers Lake on March 22, 2007 and March 25, 2008.   The first fish kill was attributed to natural conditions (winter kill) and affected 200 fish.   The 2008 fish kill was also attributed to natural conditions (winter kill) and affected 2800 fish.   According to IDNR’s assessment/listing methodology, the occurrence of a single pollutant-caused fish kill, or a fish kill of unknown origin, on a waterbody or waterbody reach during the most recent assessment period (2009-2012) indicates a severe stress to the aquatic community and suggests that the aquatic life uses should be assessed as “impaired.”  If a cause of the kill was not identified during the IDNR investigation, or if the kill was attributed to non-pollutant causes (e.g., winterkill), the assessment type will be considered “evaluated.”  Such assessments, although suitable for Section 305(b) reporting, lack the degree of confidence to support addition to the state Section 303(d) list of impaired waters (IR Category 5).   Waterbodies affected by such fish kills will be placed in IR subcategories 2b or 3b and will be added to the state list of waters in need of further investigation.  

Information from the IDNR Fisheries Bureau supports that the Class B(LW) uses are "partially supported" due to the lake’s susceptibility to fish kills due to its shallow depth and nutrient concentrations. Results of the ISU lake survey from 2010-2014 show there were no violations of the criterion for ammonia in 13 samples(0%), one violation of the criterion for dissolved oxygen in 13 samples(8%), and one violation of the criterion for pH in 13 samples(8%). Based on IDNR's assessment methodology, however, these violations are not significantly greater than 10% of the samples and therefore suggest (fully supported/monitored) of the Class B(LW) uses of Meyers Lake.

Fish consumption uses are "not assessed" due to the lack of fish contaminant monitoring at this lake.