Iowa River IA 02-IOW-646
from confluence with South Fork Iowa R. (S25 T87N R20W Hardin Co.) to confluence with Pine Cr. in S8 T87N R19W Hardin Co.
- Assessment Cycle
- 2022
- Release Status
- Final
- Data Collection Period
- Overall IR Category
- 5 - Water is impaired or threatened and a TMDL is needed.
- Trend
- Unknown
- Created
- 12/27/2021 5:48:52 AM
- Updated
- 1/4/2022 12:02:16 PM
Assessment Summary
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 "fully supported" based on water quality monitoring data and biological sampling data. The Class HH (fish consumption) use was assessed as “not supported” due to a one meal/week mercury consumption advisory for any predator fish in this segment. Note: A TMDL covering the bacteria impairments for all segments, with the segment code prefix "IA 02-IOW" in the Iowa River Basin, was approved by EPA in 2018. Due to the completion of the TMDL, the IR category for the Class A1 use was changed from 5a (impaired; TMDL needed) to 4a (impaired; TMDL approved). Because not all impairments identified for this segment are covered by the TMDL, this segment remains in Category 5 of Iowa's Integrated Report (impaired; TMDL needed).
Assessment Explanation
Data Sources: Data Source Data Source ID Data Type Data Age Site ID Site Name Site Description Iowa DNR 6 WQ CY 2018-2020 10420001 Iowa River near
Gifford Iowa DNR 6 BIO See Below 839 Iowa River Gifford
Class A1 -
Indicator Bacteria: Site ID Data Source ID # Samples per Year (2018/ 2019/2020) 2018 Geometric Mean 2019 Geometric Mean 2020 Geometric Mean Violates Annual Geometric Mean? # 2018 SSM violations / SSM Violations
needed for impairment # 2019 SSM violations / SSM Violations
needed for impairment # 2020 SSM violations / SSM Violations
needed for impairment Violates Annual SSM Significantly >10%
Rule? Assessment Type Support Level 10420001 6 7/7/8 276 208 83 YES 3 / 3 2 / 3 2 / 3 YES Monitored Not Class A - 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 10420001 6 36 / 3 7.2 8.9 8.2 0 7 NO Monitored Full Class BWW1 -
Conventional 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 10420001 6 Ammonia 36 / 3 0.025 1.2 0.1 NA 0 / 0 7 NO Monitored Full 10420001 6 Chloride 36 / 3 9.5 31 19.1 NA 0 / 0 7 NO Monitored Full 10420001 6 Dissolved Oxygen 36 / 3 7.9 14.1 10.8 0 NA / NA 7 NO Monitored Full 10420001 6 pH 36 / 3 7.2 8.9 8.2 0 NA / NA 7 NO Monitored Full 10420001 6 Sulfate 36 / 3 14 55 28 0 NA / NA 7 NO Monitored Full 10420001 6 Temperature 36 / 3 0 27.1 10.9 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 10420001 6 Aluminum 14 / 3 1.7 0.5 0.2 0 / 0 NO Monitored Full 10420001 6 Arsenic 13 / 3 2.6 1.8 1.7 0 / 0 NO Monitored Full 10420001 6 Cadmium 13 / 3 0.025 0.025 0.025 0 / 0 NO Monitored Full 10420001 6 Chromium 13 / 3 1.5 1.1 1.1 0 / 0 NO Monitored Full 10420001 6 Lead 13 / 3 0.23 0.12 0.11 0 / 0 NO Monitored Full 10420001 6 Nickel 13 / 3 4.4 3.2 3.2 0 / 0 NO Monitored Full 10420001 6 Silver 13 / 3 0.025 0.025 0.025 0 / 0 NO Monitored Full 10420001 6 Zinc 13 / 3 3 1.93 2.1 0 / 0 NO Monitored Full Site ID Date Drainage Area (mi2) Ecoregion Major Drainage BM Sample Gear BMIBI score BMIBI Class 47f BMIBI BIT BMIBI Pass/Fail 839 8/2/19 775 47f MS Floating Art Sub 66 Good 51 Pass Overall: Community Assessment Type Assessment Result Support Level IR Category Reason Benthic
Macroinvertebrates Evaluated Pass (1/1) Full Assessment was evaluated
because the drainage area of the sample site Overall Evaluated Pass Full 1 was greater than the
calibrated range. Class HH - Fish
Tissue Sampling: Support Level Not A one meal/week mercury consumption advisory for any
predator fish exists on this segment. Based on IR Methodology, the Class HH
(fish consumption) use was assessed as “not supported.”
Class BWW1 - Biological Sampling:
Benthic Macroinvertebrates:
Assessment Key Dates
1/4/2018 | Fixed Monitoring Start Date |
12/2/2020 | Fixed Monitoring End Date |
8/2/2019 | Biological Monitoring |
3/9/2018 | TMDL Completed |
Methods
150 | Monitoring data more than 5 years old |
230 | Fixed station physical/chemical (conventional plus toxic pollutants) |
260 | Fish tissue analysis |
315 | Regional reference site approach |
320 | Benthic macroinvertebrate surveys |
420 | Indicator bacteria monitoring |