Frog Hollow (aka Volga Lake) IA 01-VOL-292
Fayette County S3T93NR8W 4 mi. NNE of Fayette.
- Assessment Cycle
- 2018
- Release Status
- Final
- Data Collection Period
- Overall IR Category
- 4 - Water is impaired or threatened and a TMDL has been completed or is not needed.
- Trophic
- Eutrophic
- Trend
- Stable
- Created
- 5/8/2019 9:59:11 AM
- Updated
- 5/22/2019 1:49:13 PM
Assessment Summary
The Class A1 (primary contact recreation) uses are assessed (monitored) as “partially supported” (IR 4a) due to algae blooms and high levels of turbidity that violate Iowa’s narrative criteria protecting against aesthetically objectionable conditions. The Class B(LW) (aquatic life) uses are assessed (evaluated) as “partially supported” based on information from the IDNR Fisheries Bureau. Fish consumption uses are assessed (monitored) as "fully supported" based on results of fish tissue monitoring in 2010. Sources of data for this assessment include (1) results of the statewide survey of Iowa lakes conducted from 2012 through 2016 by Iowa State University (ISU), (2) information from the IDNR Fisheries Bureau, and (3) results of IDNR/U.S. EPA fish contaminant monitoring in 2010.
Assessment Explanation
For the 2018 assessment/listing cycle, the Class A1 (primary contact recreation) uses of Volga Lake are assessed (monitored) as "not 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 2012-2016 (approximately 15 samples), Carlson 's (1977) trophic state indices for Secchi depth, chlorophyll a, and total phosphorus were 65, 71, and 63 respectively for Volga Lake. According to Carlson (1977) the Secchi depth, chlorophyll a, and total phosphorus values all place Volga Lake in between the Eutrophic and the Hypereutrophic categories. These values suggest very high levels of chlorophyll a and suspended algae in the water, 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. Note: A TMDL for impairments due to algae and non-algal turbidity at this lake was prepared and approved by EPA in July 2014.The approval of this TMDL moves the impairments due to algae and non-algal turbidity from Iowa's list of Section 303(d) waters (Category 5a of the Integrated Report) to IR Category 4a (impaired; TMDL not required). The level of inorganic suspended solids was moderately high at Volga Lake, and does suggest that non-algal turbidity may contribute to the impairment at this lake. The median level of inorganic suspended solids in Volga Lake (4.4 mg/L) was ranked 88th among the 138 lakes by the ISU lake survey. Data from the 2012-2016 ISU lake survey suggest a moderately large population of cyanobacteria exists at Volga Lake. These data show that cyanobacteria comprised 84% of the phytoplankton wet mass at this lake. The median cyanobacteria wet mass (35.8 mg/L) was ranked 103rd of the 138 lakes sampled. he Class B(LW) (aquatic life) uses are assessed (evaluated) as “partially supported” based on information from the DNR Fisheries Bureau and results from the ISU lake surveys. Based on information from the DNR Fisheries Bureau, this lake ishighly susceptible to gully erosion, siltation, and nutrient loading. In addition, Volga lakecontains a high number of carp making it difficult for establishment of submerged aquatic vegetation.Results of the ISU lake survey from 2012-2016 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 DNR'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 Volga Lake. Fish consumption uses were assessed (monitored) as “fully supported” based on results of U.S. EPA/DNR fish contaminant (RAFT) monitoring at Volga Lake in 2010.The composite samples of fillets from largemouth bass and channel catfish had low levels of contaminants.Levels of primary contaminants in the composite sample of largemouth bass fillets were as follows: mercury: 0.119 ppm. Levels of primary contaminants in the composite sample of channel catfish fillets were as follows: mercury: 0.0948 ppm; total PCBs: 0.09 ppm; and technical chlordane: <0.03 ppm. The existence of, or potential for, a fish consumption advisory is the basis for Section 305(b) assessments of the degree to which Iowa’s lakes and rivers support their fish consumption uses. The fish contaminant data generated from the 2010 RAFT sampling conducted at this lake show that the levels of contaminants do not exceed any of the advisory trigger levels, thus indicating no justification for issuance of a consumption advisory for this waterbody.
Assessment Key Dates
6/5/2012 | TMDL Completed |
9/5/2016 | Fixed Monitoring Start Date |
9/8/2014 | Fixed Monitoring End Date |
7/30/2010 | Fish Tissue Monitoring |
7/29/2010 | Fish Tissue Monitoring |
Methods
120 | Surveys of fish and game biologists/other professionals |
260 | Fish tissue analysis |
340 | Primary producer surveys (phytoplankton/periphyton/macrophyton) |