ADBNet

Results of IDNR beach monitoring from 2012 through 2014 suggest that the Class A1 uses are "partially supported." Levels of indicator bacteria at Lake Anita Beach were monitored once per week during the primary contact recreation seasons (May through September) of 2012 (15 samples), 2013 (15 samples) and 2014 (30 samples), as part of the IDNR beach monitoring program.   According to IDNR’s assessment methodology two conditions need to be met for results of beach monitoring to indicate “full support” of the Class A1 (primary contact recreation) uses: (1) the geometric mean of the samples from each recreation season of the three-year assessment period are less than the state's geometric mean criterion of 126 E.  coli orgs/100 ml and (2) not more than 10% of the samples during any one recreation season exceeds the state's single-sample maximum value of 235 E.  coli orgs/100 ml. If a sampling season geometric mean exceeds the state criterion of 1000 orgs/100 ml during the three-year assessment period, the Class A1 uses should be assessed as “not supported.” Also, if a sampling season geometric mean exceeds the state criterion of 126 orgs/100 ml during the three-year assessment period and/or if significantly more than 10% of the samples in any one of the three recreation seasons exceed Iowa's single-sample maximum value of 235 E.  coli orgs/100 ml, the Class A1 uses should be assessed as “partially supported.” This assessment approach is based on U.S.   EPA guidelines (see pgs 3-33 to 3-35 of U.S.   EPA 1997b).

At Lake Anita Beach, the geometric means from 2012, 2013 and 2014 were all below the Iowa water quality standard of 126 E.  coli orgs/100 ml.   The geometric mean was 14 E.  coli orgs/100 ml in 2012, 16 E.  coli orgs/100 ml in 2013 and 18 E.  coli orgs/100 ml in 2014.   The percentage of samples exceeding Iowa's single-sample maximum criterion (235 E.  coli orgs/100 ml) was 0% in 2012, 7% in 2013 and 10% in 2014.   None of these are significantly greater than 10% of the samples and therefore do not suggest impairment of the Class A1 uses.   According to IDNR's assessment methodology and U.S.  EPA guidelines, these results suggest "Fully Supported" of the Class A1 uses. However, in the 2014 assessment/listing cycle, the Class A1 uses were listed as "partially supported" due to geometric mean and single sample maximum exceedances.  According to IDNR's methodology, lakes must meet water quality standards for two consecutive assessment/listing cycles to suggest de-listing.  Therefore, the Class A1 uses will remain listed as "partially supported" for the 2016 cycle. 

For the 2016 assessment/listing cycle, the Class A1 (primary contact recreation) uses of Lake Anita 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 15 samples), Carlson 's (1977) trophic state indices for Secchi depth, chlorophyll a, and total phosphorus were 67, 69, and 66 respectively for Lake Anita. According to Carlson (1977) the Secchi depth, chlorophyll a, and total phosphorus values all place Lake Anita in the Eutrophic category. These values suggest high levels of chlorophyll a and suspended algae in the water, poor water transparency, and high levels of phosphorus in the water column. The data show one violation of the Class A1 criterion for pH in 15 samples.

The level of inorganic suspended solids was low at Lake Anita, and does not suggest water quality problems due to non-algal turbidity. The median level of inorganic suspended solids in Lake Anita (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 large population of cyanobacteria exists at Lake Anita, which suggests the potential for an impairment due to nuisance aquatic life These data show that cyanobacteria comprised 96% of the phytoplankton wet mass at this lake. The median cyanobacteria wet mass (42.7 mg/L) was ranked 115th of the 138 lakes sampled. This median is in the worst 25% of the 138 lakes sampled. The presence of a large population of cyanobacteria at this lake suggests a potential violation of Iowa's narrative water quality standard protecting against the occurrence of nuisance aquatic life. This assessment is based strictly on the distribution of the lake-specific median cyanobacteria values from 2010-2014. Median levels greater than the 75th percentile of this distribution were arbitrarily considered to represent potential impairment. No other criteria exist, however, upon which to base a more accurate identification of impairments due to cyanobacteria. Assessments based on level of cyanobacteria will be considered "evaluated" (indicating an assessment with relatively lower confidence) as opposed to "monitored" (indicating an assessment with relatively higher confidence) to account for this lower level of confidence.

The Class B(LW) (aquatic life) uses are assessed (monitored) as “fully supported” based on information from the IDNR Fisheries Bureau and results from the ISU lake survey.   Information from the IDNR Fisheries Bureau suggests that the fishery at this lake has improved since the renovation in 2003. Good water clarity has led to an increase in macrophyte abundance and reducing shore angling access. 15 acres of the best shore line access will be treated with an aquatic herbicide to improve access. Results of the ISU lake survey from 2010-2014 show there were no violations of the criterion for ammonia in 15 samples(0%), one violation of the criterion for dissolved oxygen in 15 samples(7%), and one violation of the criterion for pH in 15 samples(7%). 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 Anita.

Fish consumption uses are assessed (monitored) as “fully supported” based on results of U.S.EPA/IDNR fish contaminant (RAFT) monitoring at Lake Anita in 1997 and 2006 and turtle contaminant monitoring in 2009.   The existence of, or potential for, a fish consumption advisory is the basis for Section 305(b) assessments of support of fish consumption uses in Iowa’s rivers and lakes.   The fish contaminant data generated from the 1997 RAFT sampling conducted at Lake Anita show that levels of all contaminants from this monitoring were below advisory trigger levels.   Follow up sampling conducted in 2006 showed that the composite samples of fillets from largemouth bass had levels of mercury below the advisory trigger level of 0.3 ppm.   The level of mercury in the composite sample of largemouth bass fillets was 0.252 ppm.   In addition turtle contaminant monitoring in 2009 showed low levels of primary contaminants.   Levels of primary contaminants in the turtle shoulder muscle were as follows: mercury: 0.171 ppm; total PCBs: 0.09 ppm; and technical chlordane: <0.03 ppm.   According to IDNR's assessment methodology these results suggest "full support" of the fish consumption uses at Lake Anita.