Raccoon River IA 04-RAC-1116
mouth (at Des Moines Polk Co.) to the Polk/Dallas county line
- Cycle
- 2026
- Current Phase
- Public Comment
- Overall IR
- 4 - Water is impaired or threatened and a TMDL has been completed or is not needed.
- Trend
- Stable
- Created
- 10/27/2025 3:10:03 PM
- Updated
- 12/23/2025 4:35:43 AM
The Class A1 use was assessed as "not supported" based on indicator bacteria (E. coli) monitoring data. The Class BWW1 use was assessed as "fully supported" based on ambient chemical/physical water quality monitoring data. The Class C use was assessed as "not supported" based on water quality monitoring data. All other designated uses were “not assessed.” Note: A TMDL for nitrate and pathogen indicators (E. coli) was prepared by DNR and approved by EPA in June 2008. Because this TMDL covers both of the Section 303(d) impairments identified for this IR cycle, the Class A1 and Class C designated uses were 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 DMWW 13 WQ CY
2022-2024 99990003 Raccoon River
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 99990003 13 170/170/158 99 94 158 YES 45 / 23 42 / 23 54 / 22 YES MONITORED NOT 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 99990003 13 759 / 3 7.46 8.97 8.29 0 88 NO MONITORED FULL 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 99990003 13 Chloride 759 / 3 12.99 210.52 37.78 NA 0 / 0 88 NO MONITORED FULL 99990003 13 pH 759 / 3 7.46 8.97 8.29 0 NA / NA 88 NO MONITORED FULL 99990003 13 Sulfate 759 / 3 13.92 82.11 46.33 0 NA / NA 88 NO MONITORED FULL 99990003 13 Temperature 758 / 3 -1.11 30 12.61 0 NA / NA 87 NO MONITORED FULL 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 99990003 13 Ammonia 757 / 3 1.42 0.06 0.01 0 / 0 NO MONITORED FULL 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 99990003 13 Chloride 759 / 3 12.99 210.52 37.78 35.45 0 NO MONITORED FULL 99990003 13 Fluoride 759 / 3 100 480 301 300 0 NO MONITORED FULL 99990003 13 Nitrate 759 / 3 0.05 18.23 4.06 2.63 99 YES MONITORED NOT 99990003 13 Nitrite 760 / 3 0.05 0.15 0.05 0.05 0 NO MONITORED FULL 99990003 13 pH 759 / 3 7.46 8.97 8.29 8.31 0 NO MONITORED FULL Compliance monitoring required by the Iowa DNR Water Supply
Operations and Engineering Sections did not show violations of finished water
caused by source water at the Des Moines Water Works facility during the 2022-24
monitoring period. 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 - No Data
Class A1 - Indicator Bacteria:
Class A1 - pH:
Class BWW1 - Binomial Parameters:
Class BWW1 - Toxic Parameters:
Class C - Binomial Parameters:
Class C - Iowa Drinking Water Compliance Report: