Little Wall Lake IA 03-SSK-941
Hamilton County S10T86NR24W 1 mi. S of Jewell
- Cycle
- 2020
- Release Status
- Final
- Overall IR
- 4 - Water is impaired or threatened and a TMDL has been completed or is not needed.
- Trophic
- Hypereutrophic
- Trend
- Declining
- Trend Comment
- Both the Secchi and chlorophyll a TSI values increased over the last three assessment/listing cycles (2014, 2016 and 2018). Secchi TSI went from 73 (2014) to 83 (2018) and chlorophyll a TSI went from 63 (2014) to 72 (2018). This increase in TSI values suggests a degradation water quality. Cyanobacteria continues to be a problem at this lake.
- Created
- 7/30/2020 3:39:51 PM
- Updated
- 11/23/2020 3:39:15 PM
The Class A1uses are assessed (monitored) as “not supported” due to aesthetically objectionable conditions caused by poor water transparency and nuisance algae blooms and by levels of pH that violate Iowa’s water quality criterion. The Class BLW uses are assessed (evaluated) as “partially supported” based on cyanobacteria blooms. All other designated uses are “not assessed”. Note: A TMDL for algae and turbidity at Little Wall Lake was prepared by DNR and approved by EPA in 2006. Because all Section 303(d) impairments identified for the current assessment/listing cycle (algal growth and turbidity) are addressed by the TMDL, this waterbody is placed in IR Category 4a (impaired; TMDL approved).
Sources of
Data: Data Source Data Source ID Data Type Data Age Site ID Site Name Site Description Iowa DNR 6 WQ CY 2014-2018 22400001 Little Wall Lake (maximum water depth)
Class A1 -
Indicator Bacteria: No Data Class A1 - pH: Site ID Data Source ID # Samples / # Years Maximum Value Mean Value Median Value # Violations % Violations Significantly >10% Violations Assessment Type Support Level 22400001 6 15 / 5 9.19 8.52 8.5 1 7% NO Monitored 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 22400001 6 Chlorophyll a TSI 15 / 5 36 79 69 YES Monitored Not 22400001 6 Secchi TSI 15 / 5 70 93 83 YES Monitored Not 22400001 6 Total Phosphorus TSI 15 / 5 60 82 75 NA NA NA 22400001 6 Inorganic suspended solids 15 / 5 0.4 60 14 NA NA NA Class BLW -
Conventional Parameters: Site ID Data Source ID Parameter Name # Samples / # Years Maximum Value Mean Value Median Value # Acute / Chronic Violations % Acute/ Chronic Violations Significantly >10% Violations Assessment Type Support Level 22400001 6 Ammonia 15 / 5 0.04 0.01 0.01 0 / 0 0% / 0% NO Monitored Full 22400001 6 Dissolved oxygen 15 / 5 10 7.7 7.7 NA / 1 NA / 7% NO Monitored Full 22400001 6 pH 15 / 5 9.19 8.52 8.5 1 / NA 7% / NA NO Monitored Full 22400001 6 Temperature 15 / 5 27.8 24.1 23.5 0 / 0 0% / 0% NO Monitored Full 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 Wet Mass = 75th
Percentile Assessment Type Support Level 22400001 6 11 855.203 99.9 % 202.115 93.8 % YES Evaluated 3b Class HH - No Data The fish consumption uses assessment was changed to "Not Assessed" based on the age of the data.