Littlefield Lake IA 05-NSH-1439
Audubon County S17T78NR34W approx 4 mi SE of Exira.
- Cycle
- 2026
- Current Phase
- Public Comment
- Overall IR
- 5 - Water is impaired or threatened and a TMDL is needed.
- Trophic
- Hypereutrophic
- Trend
- Stable
- Created
- 10/27/2025 3:10:16 PM
- Updated
- 11/21/2025 3:17:42 PM
The Class A1 use was assessed (monitored) as “not supported” due to aesthetically objectionable conditions caused by poor water transparency, nuisance algae blooms and due to violations of the pH criteria. The Class BLW use was assessed (monitored) as “not supported” due to violations of the pH criteria. The Class HH use was assessed (monitored) as "fully supported" based on fish tissue monitoring. Note: A TMDL for algae and turbidity at Littlefield 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).
Data Sources: Data Source Data Source ID Data Type Data Age Site ID Site
Name Site
Description Iowa DNR 6 WQ CY 2020-2024 22050001 Littlefield
Lake (maximum water depth)
Iowa DNR 6 FT See Below 1312 Littlefield
Lake
Class A - 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 22050001 6 15 / 5 7.9 9.4 8.8 6 4 YES MONITORED NOT 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 22050001 6 Chlorophyll a TSI 15 / 5 50 91 76 YES MONITORED NOT 22050001 6 Secchi TSI 15 / 5 48 97 79 YES MONITORED NOT 22050001 6 Total Phosphorus TSI 15 / 5 60 94 82 NA NA NA 22050001 6 Fixed suspended solids 15 / 5 1.9 32 5.6 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 22050001 6 Dissolved Oxygen 14 / 5 3 12.4 7.3 1 NA / NA 4 NO MONITORED FULL 22050001 6 pH 15 / 5 7.9 9.4 8.8 6 NA / NA 4 YES MONITORED NOT 22050001 6 Temperature 15 / 5 20.2 28.1 24.2 0 NA / NA 4 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 Concentration = 75th Percentile Assessment Type Support Level 22050001 6 3 26.34720993 98.47% 0.69123958 2.27% 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 22050001 6 Ammonia 15 / 5 0.293 0.07 0.05 0 / 0 NO MONITORED FULL Class HH - Fish
Tissue Sampling: Site ID Biopart Year Species # in sample / # of samples Avg Length (cm) (Avg) Hg (ppm) Chlordane (ppm) Sum PCBs (ppm) 1312 fillet 2024 channel catfish 3 48.1 0.02 <0.0499 <0.0246 Support Level Full