Yellow River IA 01-YEL-434
mouth (S34 T96N R3W Allamakee Co.) to County Road X-26 bridge in S24 T96N R5W Allamakee Co.
- Cycle
- 2026
- Current Phase
- Public Comment
- Overall IR
- 5 - Water is impaired or threatened and a TMDL is needed.
- Trend
- Declining
- Trend Comment
- New aquatic life benthic macroinvertebrate impairment.
- Created
- 10/27/2025 3:09:38 PM
- Updated
- 1/5/2026 6:59:20 AM
The Class A1 use was assessed as "not supported" due to levels of indicator bacteria (E. coli) that exceeded state water quality criteria. The Class BWW1 use was assessed as "not supported" based on benthic macroinvertebrate sampling data. The Class HH use was assessed as "fully supported" based on water quality monitoring data. Note: A TMDL for the bacterial impairment for Yellow River basin streams was prepared by Iowa DNR in 2012 and approved by U.S. EPA in 2013. Due to the TMDL completion, the Integrated Report category for the Class A1 primary contact recreation use was changed from 5a to 4a.
Data Sources: Data Source Data Source ID Data Type Data Age Site ID Site
Name Site
Description Iowa DNR 6 WQ CY 2022-2024 10030002 Yellow
River at Ion
Iowa DNR 6 BIO See Below 141 Yellow River Yellow River State
Forest – Yellow River Unit - Ion Iowa DNR 6 BIO See Below 1149 Yellow River County Road X36
bridge – 3 miles S of Hwy 76 - Ion 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 10030002 6 8/8/8 317 157 272 YES 4 / 3 2 / 3 3 / 3 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 10030002 6 35 / 3 8 8.4 8.2 0 7 NO MONITORED 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 10030002 6 Copper 18 / 2 2.1 0.8 0.5 11 NO MONITORED FULL Site ID Data Source ID Parameter Name # Samples per Year
(2022/ 2023/2024) 2022 Mean 2023 Mean 2024 Mean # Non-Detects per
Year (2022/ 2023/2024) Support Level per
Year (2022/ 2023/2024) Assessment Type Support Level 10030002 6 Selenium 12/12/12 0.542 0.5 0.55 11/12/11 FS/FS/FS 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 10030002 6 Chloride 36 / 3 15 30 21 NA 0 / 0 7 NO MONITORED FULL 10030002 6 Dissolved Oxygen 36 / 3 8.6 15.2 11.6 0 NA / NA 7 NO MONITORED FULL 10030002 6 pH 35 / 3 8 8.4 8.2 0 NA / NA 7 NO MONITORED FULL 10030002 6 Sulfate 36 / 3 11 22 16 0 NA / NA 7 NO MONITORED FULL 10030002 6 Temperature 36 / 3 0 22.1 10.6 0 NA / NA 7 NO MONITORED FULL Class BWW1 - 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 10030002 6 Ammonia 35 / 3 0.55 0.05 0.02 0 / 0 NO MONITORED FULL 10030002 6 Cadmium 18 / 2 0.5 0.5 0.5 0 / 0 NO MONITORED FULL 10030002 6 Chromium 18 / 2 15 1.9 1 0 / 1 NO MONITORED FULL 10030002 6 Copper 18 / 2 2.1 0.8 0.5 0 / 0 NO MONITORED FULL 10030002 6 Lead 18 / 2 1 1 1 0 / 0 NO MONITORED FULL 10030002 6 Nickel 18 / 2 1.8 0.9 0.8 0 / 0 NO MONITORED FULL 10030002 6 Selenium 36 / 3 1.1 0.5 0.5 0 / 0 NO MONITORED FULL 10030002 6 Silver 18 / 2 1 1 1 0 / 0 NO MONITORED FULL 10030002 6 Zinc 18 / 2 1.2 0.6 0.5 0 / 0 NO MONITORED FULL Class BWW1 -
Biological Sampling: Benthic Macroinvertebrates: Site ID Date Drainage Area (mi2) Ecoregion Major Drainage BM Sample Gear BMIBI score BMIBI Class 52b BMIBI BIT BMIBI Pass/Fail 141 9/5/24 221.0 52b MS Hess 59 Good 61 Fail 1149 7/15/21 221.0 52b MS Hess 61 Good 61 Pass 141 8/20/20 224.4 52b MS Hess 57 Good 61 Fail Site ID Date Drainage Area (mi2) Ecoregion Major Drainage Riffle Stream? FIBI score FIBI Class 52b FIBI BIT FIBI Pass/Fail 141 9/9/24 224.4 52b MS NA 71 Excellent 52 Pass 141 8/20/20 224.4 52b MS NA 50 Fair 52 Fail Community Assessment Type Assessment Result Support Level IR Category Reason Benthic
Macroinvertebrates Monitored Fail (1/3) Not Fish Evaluated Fail (1/2) WINOFI Assessment was monitored because the BMIBI samples used to complete Overall Monitored Fail Not 5bv the assessment were collected in a recent five-year period.
Aquatic Life Use - Trout Natural Reproduction
Based on the latest trout reproduction in Iowa streams summary prepared by the DNR Fisheries Bureau, the aquatic life use was assessed as "fully supported." According to the summary, a portion, or all, of this assessment unit was placed in Category I: streams that exhibit consistent natural reproduction and maintain a wild population of one or more trout species without any stocking.
Class HH-F - Toxic
Parameters:
Class BWW1 - Conventional Parameters:
Fish:
Overall: