Lake Meyer IA 01-TRK-158

For the 2016 assessment/listing cycle, the Class A1 (primary contact recreation) uses of Lake Meyer are assessed (monitored) as “partially supported” based on information from the ISU lake survey. Using the median values from these surveys from 2010-2014 (approximately 15 samples), Carlson 's (1977) trophic state indices for Secchi depth, chlorophyll a, and total phosphorus were 62, 64, and 64 respectively for Lake Meyer. According to Carlson (1977) the Secchi depth, chlorophyll a, and total phosphorus values all place Lake Meyer in the Eutrophic category. These values suggest moderately high levels of chlorophyll a and suspended algae in the water, moderately poor water transparency, and moderately high levels of phosphorus in the water column. The data show no violations of the Class A1 criterion for pH in 15 samples. The Secchi depth and chlorophyll a index values are both below the impairment trigger of 65, however, Lake Meyer was listed as "partially supporting" the Class A1 uses for the 2012 assessment/listing cycle for elevated levels of chlorophyll a (TSI = 65).  Based on IDNR's assessment methodology, median-based TSI values for both chlorophyll a and Secchi depth must be 63 of less for two consecutive assessment/listing cycles before a lake can be removed from the states Section 303(d) list.  Therefore, the Class A1 will remain listed as "partially supported" due to algae for the 2016 IR cycle.

Note 1:  A TMDL for nutrients and siltation at Lake Meyer was prepared by IDNR and approved by EPA in 2005.   Because all Section 303(d) impairments identified for the 2016 assessment/listing cycle (algae growth) are potentially addressed by the TMDL, this waterbody is placed in IR Category 4a (impaired; TMDL approved).

The level of inorganic suspended solids was low at Lake Meyer, and does not suggest water quality problems due to non-algal turbidity. The median level of inorganic suspended solids in Lake Meyer (2 mg/L) was ranked 10th 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 Lake Meyer. These data show that cyanobacteria comprised 78% of the phytoplankton wet mass at this lake. The median cyanobacteria wet mass (18.4 mg/L) was ranked 59th of the 138 lakes sampled.

The Class B(LW) (aquatic life) uses are assessed (evaluated) as “partially supported” due nutrient loading and eutrophic conditions at Lake Meyer.   This BPJ-based potential impairment is not appropriate for Iowa’s Section 303(d) list of impaired waters (Integrated Report Category 5) but is appropriate for IR Category 3b of Iowa’s Integrated Report and Iowa’s list of waters in need of further investigation.   Results of the ISU lake surveys, however, suggest good chemical water quality at Lake Meyer. Results of the ISU lake survey from 2010-2014 show there were no violations of the criterion for ammonia in 15 samples(0%), 2 violations of the criterion for dissolved oxygen in 15 samples(13%), and no violations of the criterion for pH in 15 samples(0%). Based on IDNR's assessment methodology these violations are not significantly greater than 10% of the samples and therefore suggest (fully supported/monitored) of the Class B(LW) uses of Lake Meyer.

Fish consumption uses are "not assessed" due to the lack of recent fish contaminant monitoring at this lake.   The most recent fish contaminant monitoring was conducted in 1994 as part of the U.S.  EPA/IDNR (RAFT) program.   Although results of the 1994 RAFT monitoring at Lake Meyer indicated very low levels of contaminants and “full support” of the fish consumption uses, these data are now considered too old (greater than ten years) to characterize current water quality conditions.

Note 2: In 2015, Lake Meyer was lowered 10 feet to create water retention basins and in-lake habitat could be installed. In addition, sediment was removed and the dam was repaired.