East Lake (Osceola) IA 04-LDM-1065
Clarke County S16T72NR25W 0.5 mi E of Osceola.
- Assessment Cycle
- 2024
- Release Status
- Pending
- Data Collection Period
- Overall IR Category
- 5 - Water is impaired or threatened and a TMDL is needed.
- Trophic
- Hypereutrophic
- Trend
- Stable
- Created
- 11/1/2023 8:13:05 AM
- Updated
- 2/5/2024 8:33:02 AM
Assessment Summary
The Class A1 use was assessed (monitored) as "not supported" due to poor water transparency. The Class BLW use was assessed (monitored) as "not supported" due to frequent violation of the dissolved oxygen criteria. Additionally, the Class BLW use was assessed (evaluated) as "WINOFI" due to excessive nutrient loading to the water column and impacts from organic enrichment. All other designated uses were “not assessed.” NOTE: A TMDL for algae and turbidity for East Lake was completed by DNR and approved by EPA in 2008. Thus, these impairments were moved from IR Category 5a (impaired; TMDL required) to Category 4a (impaired; TMDL approved). Because not all of the impairments are identified for this lake are covered by this TMDL (Dissolved Oxygen), this lake is placed in IR Category 5a.
Assessment Explanation
Data Sources: Data Source Data Source ID Data Type Data Age Site ID Site
Name Site
Description Iowa DNR 6 WQ CY 2018-2022 22200001 East
Lake Osceola
Class A1 - Indicator Bacteria: No Data Class A1 - pH: Site ID Data Source ID # Samples / # Years Minimum Value Maximum Value Mean Value # Violations Violations needed for impairment Violates Significantly >10% Rule? Assessment Type Support Level 22200001 6 15 / 5 6.7 9.2 8.3 2 4 NO Mon Full Class A1 - Lake TSI’s: Site ID Data Source ID Parameter Name # Samples / # Years Minimum Value Maximum Value Median Value Median TSI Violation? Assessment Type Support Level 22200001 6 Chlorophyll a TSI 15 / 5 37 88 64 NO Mon Full 22200001 6 Secchi TSI 15 / 5 47 83 67 YES Mon Not 22200001 6 Total Phosphorus TSI 15 / 5 63 100 86 NA NA NA 22200001 6 Inorganic suspended solids 15 / 5 0.6 9 5 NA NA NA Class BLW - Binomial Parameters: Site ID Data Source ID Parameter Name # Samples / # Years Minimum Value Maximum Value Mean Value # Violations # Acute / Chronic Violations Violations needed for impairment Violates Significantly >10% Rule? Assessment Type Support Level 22200001 6 Dissolved Oxygen 14 / 5 2.52 10.73 6.78 4 NA / NA 4 YES Mon Not 22200001 6 pH 15 / 5 6.7 9.2 8.3 2 NA / NA 4 NO Mon Full 22200001 6 Temperature 15 / 5 18.3 28.8 24.6 0 NA / NA 4 NO Mon Full Note: The Class BLW use was assessed (evaluated) as “WINOFI”
due to algae blooms and poor water quality that put the lake at risk for a fish
kill based on information from the DNR Fisheries bureau. Class BLW - Lake Planktonic Cyanobacteria: Site ID Data Source ID # Samples Maximum Cyanobacteria Wet Mass Maximum Cyanobacteria % Composition Median Cyanobacteria Wet Mass Median Cyanobacteria % Composition Median Cyanobacteria Concentration = 75th Percentile Assessment Type Support Level 22200001 6 6 5.401825821 19% 0.485453757 2% NO Evaluated NA Class BLW - Toxic Parameters: Site ID Data Source ID Parameter Name # Samples / # Years Maximum Value Mean Value Median Value # Acute / Chronic Violations >1 Acute / Chronic Violation Assessment Type Support Level 22200001 6 Ammonia 15 / 5 0.294 0.08 0.04 0 / 0 NO Mon Full
Class HH - No Data
Assessment Key Dates
| 5/22/2018 | Monitoring Start |
| 9/21/2022 | Monitoring End |
| 5/14/2008 | TMDL Completed |
Methods
| 200 | Physical/Chemical Monitoring |
| 340 | Primary producer surveys (phytoplankton/periphyton/macrophyton) |