Big Spirit Lake IA 06-LSR-1655
Dickinson County S33T100NR36W at Spirit Lake
- Cycle
- 2026
- Current Phase
- Public Comment
- Overall IR
- 5 - Water is impaired or threatened and a TMDL is needed.
- Trophic
- Eutrophic
- Trend
- Stable
- Created
- 10/27/2025 3:10:31 PM
- Updated
- 1/2/2026 10:52:40 AM
The Class A1 use was assessed (monitored) as “not supported” due to violations of the state water quality criteria for indicator bacteria. The Class BLW use was assessed (evaluated) as “WINOFI” based on the results of fish kill investigations. In addition, the Class BLW use was assessed (evaluated) as “WINOFI” due to cyanobacteria blooms. The Class C use was assessed (monitored) as “fully supported” based on water quality monitoring data and drinking water compliance monitoring required by the DNR. The Class HH (fish consumption) use was assessed (evaluated) as “WINOFI” based on fish tissue sampling data.
Data Sources: Data Source Data Source ID Data Type Data Age Site ID Site
Name Site
Description Iowa DNR 6 WQ CY 2022-2024 14000380 Marble
Beach (Marble Beach State Park)
Iowa DNR 6 WQ CY 2022-2024 21300005 Crandalls
Beach
Iowa DNR 6 WQ CY 2022-2024 21300007 Orleans
City Beach
Iowa DNR 6 WQ CY 2020-2024 22300014 Big
Spirit Lake Deep
Point Iowa DNR 6 FT See Below 1153 Big
Spirit Lake
Class A1 - Indicator Bacteria: Site ID Data Source ID # Samples per Year (2022/ 2023/2024) 2022 Geometric Mean 2023 Geometric Mean 2024 Geometric Mean Violates Annual Geometric Mean? # 2022 SSM violations / SSM Violations needed for impairment # 2023 SSM violations / SSM Violations needed for impairment # 2024 SSM violations / SSM Violations needed for impairment Violates Annual SSM Significantly >10% Rule? Assessment Type Support Level 14000380 6 15/14/12 34 61 28 NO 2 / 4 3 / 4 2 / 4 NO MONITORED FULL 21300005 6 15/14/12 16 96 53 NO 1 / 4 5 / 4 2 / 4 YES MONITORED NOT 21300007 6 15/14/12 29 68 21 NO 1 / 4 5 / 4 1 / 4 YES MONITORED NOT 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 22300014 6 12 / 4 7.99 8.98 8.5 0 4 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 22300014 6 Chlorophyll a TSI 15 / 5 29 75 58 NO MONITORED FULL 22300014 6 Secchi TSI 15 / 5 41 73 53 NO MONITORED FULL 22300014 6 Total Phosphorus TSI 15 / 5 37 82 58 NA NA NA 22300014 6 Fixed suspended solids 15 / 5 0.7 3.2 2 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 22300014 6 Dissolved Oxygen 12 / 5 5.4 11.5 8.6 0 NA / NA 4 NO MONITORED FULL 22300014 6 pH 12 / 4 7.99 8.98 8.5 0 NA / NA 4 NO MONITORED FULL 22300014 6 Temperature 13 / 5 18.1 26.9 23 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 22300014 6 3 13.89844 37.86% 0.026078 16.56% 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 22300014 6 Ammonia 12 / 4 0.046 0.02 0.02 0 / 0 NO MONITORED FULL Class BLW - Fish Kill Assessment: The Class BLW aquatic life use assessment based on the June 2020 fish kill placed this segment in Category 3b. This assessment was “evaluated” because: (1) the cause of the fish kill was not identified or (2) the fish kill was attributed to a non-pollutant cause (e.g., winterkill). Segments assessed using “evaluated” assessments are placed in Category 3b and are added to the state list of Waters In Need Of Further Investigation (WINOFI). If no additional fish kills are reported in this segment for a 5-year period (2023), the Category will be changed from 3b to 3a (not assessed). Details about the 2020 fish kill can be found here:https://programs.iowadnr.gov/fishkill/Events/996 Class C - Binomial Parameters: Site ID Data Source ID Parameter Name # Samples / # Years Minimum Value Maximum Value Mean Value Median Value # Violations Violates Significantly >10% Rule? Assessment Type Support Level 22300014 6 Inorganic nitrogen (nitrate and nitrite) 14 / 5 0.03 0.32 0.1 0.06 0 NO MONITORED FULL 22300014 6 pH 12 / 4 7.99 8.98 8.5 8.6 0 NO MONITORED FULL Class C - Iowa Drinking Water Compliance Report: Compliance monitoring required by the Iowa DNR Water Supply Operations and Engineering Sections did not show violations of finished water that were caused by source water at the Spirit Lake Waterworks facility during the 2022-24 monitoring period. The violations reported were related to plant operations (Failure to maintain Res Disinfect Concentration).The results of compliance monitoring as reported in annual compliance reports are available at the following location at the Iowa DNR’s home page: https://www.iowadnr.gov/Environmental-Protection/Water-Quality/Water-Supply-Engineering/Annual-Compliance-Report. 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) 1153 tissue plug 2021 muskie 1
0.370
1153 tissue plug 2020 muskie 3 95.1 0.192
1153 tissue plug 2019 northern pike 20 65.6 0.113
1153 tissue plug 2020 walleye 13 49.1 0.25
1153 tissue plug 2019 walleye 7 48.9 0.171
1153 tissue plug 2020 yellow perch 10 23.6 0.041
Support Level WINOFI