Mississippi River IA 01-NEM-75
from Lock & Dam 11 at north side of Dubuque (Dubuque Co.) to Lock & Dam 10 at Guttenberg (Clayton Co.)
- Cycle
- 2026
- Current Phase
- Public Comment
- Overall IR
- 2 - Some of the designated uses are met but there is insufficient data to determine if remaining designated uses are met.
- Trend
- Stable
- Created
- 10/27/2025 3:10:10 PM
- Updated
- 12/22/2025 10:38:25 AM
The Class A1 use was assessed as "fully supported" based on water quality monitoring data. The Class BWW1 use was assessed as “fully supported” based on water quality monitoring data. The Class HH use was assessed as "WINOFI" based fish tissue sampling data. According to DNR’s assessment methodology, the one-time occurrence of a level of mercury above an advisory trigger level does not suggest impairment of the fish consumption use. The Iowa DNR/DPH advisory protocol states that two consecutive samplings that show contaminant levels are above the trigger level in edible tissue are needed to justify issuance of an advisory.
Data Sources: Data Source Data Source ID Data Type Data Age Site ID Site
Name Site
Description IEPA 10 WQ CY 2022-2024 99990018 Mississippi
River
Iowa DNR 6 FT See Below 1142 Mississippi
River downstream
of Guttenberg Iowa DNR 6 FT See Below 1381 Mississippi
River Guttenberg
Boat Ramp 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 99990018 10 6 / 2 6.4 8.6 7.8 1 3 NO EVALUATED 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 99990018 10 Chloride 6 / 2 14.1 25.7 20.1 NA 0 / 0 3 NO EVALUATED FULL 99990018 10 Dissolved Oxygen 6 / 2 6.6 14 10.1 0 NA / NA 3 NO EVALUATED FULL 99990018 10 pH 6 / 2 6.4 8.6 7.8 1 NA / NA 3 NO EVALUATED FULL 99990018 10 Sulfate 6 / 2 17.7 44.5 29.3 0 NA / NA 3 NO EVALUATED FULL 99990018 10 Temperature 6 / 2 0 25.7 13.4 0 NA / NA 3 NO EVALUATED 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 99990018 10 Aluminum 6 / 2 959 373 298 0 / 1 NO EVALUATED FULL 99990018 10 Ammonia 6 / 2 0.36 0.12 0.07 0 / 0 NO EVALUATED FULL 99990018 10 Arsenic 6 / 2 18.5 3.9 1 0 / 0 NO EVALUATED FULL 99990018 10 Cadmium 6 / 2 184 31.9 1.5 1 / 1 NO EVALUATED FULL 99990018 10 Chromium 6 / 2 2.5 2.4 2.5 0 / 0 NO EVALUATED FULL 99990018 10 Copper 6 / 2 2.5 2.5 2.5 0 / 0 NO EVALUATED FULL 99990018 10 Cyanide 6 / 2 1 1 1 0 / 0 NO EVALUATED FULL 99990018 10 Lead 6 / 2 2.5 2.2 2.5 0 / 0 NO EVALUATED FULL 99990018 10 Nickel 6 / 2 2.5 2.5 2.5 0 / 0 NO EVALUATED FULL 99990018 10 Phenols 6 / 2 6.67 5.28 5 0 / 0 NO EVALUATED FULL 99990018 10 Selenium 6 / 2 2.5 2.5 2.5 0 / 0 NO EVALUATED FULL 99990018 10 Silver 6 / 2 3.4 1.8 1.5 0 / 0 NO EVALUATED FULL 99990018 10 Zinc 6 / 2 5 5 5 0 / 0 NO EVALUATED FULL Site ID Data Source ID Parameter Name # Samples / # Years Maximum Value Mean Value Median Value Number of Non - Detects Mean Value > Criterion or MCL Assessment Type Support Level 99990018 10 Arsenic 6 / 2 2.18 1.26 1.02 3 NO EVALUATED FULL 99990018 10 Cadmium 6 / 2 1.5 1.5 1.5 6 NO EVALUATED FULL 99990018 10 Chromium 6 / 2 2.5 2.1 2.5 4 NO EVALUATED FULL 99990018 10 Chromium (VI) 6 / 2 2.5 2.1 2.5 4 NO EVALUATED FULL 99990018 10 Copper 6 / 2 2.5 2.5 2.5 6 NO EVALUATED FULL 99990018 10 Cyanide 6 / 2 1 1 1 6 NO EVALUATED FULL 99990018 10 Nickel 6 / 2 2.5 2.5 2.5 5 NO EVALUATED FULL 99990018 10 Phenols 6 / 2 6.67 5.28 5 5 NO EVALUATED FULL 99990018 10 Selenium 6 / 2 2.5 2.5 2.5 6 NO EVALUATED FULL 99990018 10 Zinc 6 / 2 7.96 5.49 5 5 NO EVALUATED FULL Site ID Biopart Year Species # in sample / # of samples Avg Length (cm) (Avg) Hg (ppm) Chlordane (ppm) Sum PCBs (ppm) 1381 tissue plug 2020 largemouth bass 20 32.7 0.244 1381 tissue plug 2020 northern pike 20 60.0 0.190 1381 tissue plug 2020 sauger 35 31.1 0.142 1381 tissue plug 2020 shovelnose sturgeon 10 49.3 0.056 1381 tissue plug 2020 walleye 15 43.6 0.207 1381 tissue plug 2020 yellow perch 20 22.3 0.082 1381 tissue plug 2021 freshwater drum 40 45.5 0.338 1142 fillet 2023 channel catfish 3 41.9 0.096 <0.05 0.0483 Support Level WINOFI 3b
Class A1 - Indicator Bacteria: No Data
Class BWW1 - Binomial Parameters:
Class BWW1 - Toxic Parameters:
Class HH-F - Toxic Parameters:
Class HH - Fish
Tissue Sampling: