West Nishnabotna River IA 05-NSH-1441
from confluence with Silver Cr. (S21 T71N R41W Mills Co.) to confluence Farm Cr. in S9 T73N R40W Mills Co.
- Assessment Cycle
- 2024
- Release Status
- Pending
- Data Collection Period
- Overall IR Category
- 5 - Water is impaired or threatened and a TMDL is needed.
- Trend
- Unknown
- Created
- 11/1/2023 8:13:02 AM
- Updated
- 1/3/2024 9:37:49 AM
Assessment Summary
The Class A1 use was assessed as "not supported" due to levels of indicator bacteria (E. coli) that violated state water quality criteria. The Class BWW1 use was assessed as "WINOFI" based on biological sampling data. The Class HH use was assessed as "fully supported" based on water quality monitoring data.
Assessment Explanation
Data Sources: Data Source Data Source ID Data Type Data Age Site ID Site
Name Site
Description Iowa DNR 6 WQ CY 2014-2016, 2020-2022 10650001 West
Nishnabotna River near Malvern
Iowa DNR 6 BIO See Below 935 West
Nishnabotna River Malvern Site ID Data Source ID # Samples / # Years 2014 Geo. Mean 2015 Geo. Mean 2016 Geo. Mean Annual Geometric Mean Violation # Violations % Violations Significantly >10% Violations Assessment Type Support Level 10650001 6 24 / 3 1295 1293 661 Yes 18 75% Yes Evaluated 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 10650001 6 36 / 3 7.4 8.6 8.2 0 7 NO Mon 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 10650001 6 Chloride 36 / 3 14 27 19 NA 0 / 0 7 NO Mon Full 10650001 6 Dissolved Oxygen 36 / 3 7.4 13.7 10.2 0 NA / NA 7 NO Mon Full 10650001 6 pH 36 / 3 7.4 8.6 8.2 0 NA / NA 7 NO Mon Full 10650001 6 Sulfate 36 / 3 21 42 31 0 NA / NA 7 NO Mon Full 10650001 6 Temperature 36 / 3 0 30 15 0 NA / NA 7 NO Mon 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 10650001 6 Ammonia 36 / 3 0.1 0.03 0.02 0 / 0 NO Mon Full 10650001 6 Cadmium 19 / 3 0.5 0.4 0.5 0 / 0 NO Mon Full 10650001 6 Chromium 19 / 3 6 0.97 0.74 0 / 0 NO Mon Full 10650001 6 Lead 19 / 3 1 0.9 1 0 / 0 NO Mon Full 10650001 6 Nickel 19 / 3 3.3 1.7 1.5 0 / 0 NO Mon Full 10650001 6 Selenium 18 / 2 7 3 3 0 / 1 NO Mon Full 10650001 6 Silver 19 / 3 1 0.897 1 0 / 0 NO Mon Full 10650001 6 Zinc 19 / 3 5 1.2 0.5 0 / 0 NO Mon Full Site ID Date Drainage Area (mi2) Ecoregion Major Drainage BM Sample Gear BMIBI score BMIBI Class 47e BMIBI BIT BMIBI Pass/Fail 935 8/13/20 967 47e MO Floating Art Sub 22 Poor 54 Fail 935 9/7/16 967 47e MO Floating Art Sub 42 Fair 54 Fail Community Assessment Type Assessment Result Support Level IR Category Reason Benthic
Macroinvertebrates Evaluated Fail (0/2) WINOFI Assessment was evaluated because the
drainage area of the sample site Overall Evaluated Fail WINOFI 3bu was greater than the calibrated range. 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 10650001 6 Selenium 18 / 2 7 3 3 0 NO Mon Full
Class A1 - Indicator Bacteria: 2014-2016
Class A1 – pH:
Class BWW1 - Binomial Parameters:
Class BWW1 - Toxic Parameters:
Class BWW1 - Biological Sampling:
Benthic Macroinvertebrates:
Overall:
Class HH-F - Toxic Parameters:
Assessment Key Dates
| 8/13/2020 | Biological Monitoring |
| 1/7/2014 | Monitoring Start |
| 12/6/2016 | Monitoring End |
| 9/7/2016 | Biological Monitoring |
| 1/6/2020 | Monitoring Start |
| 12/12/2022 | Monitoring End |
Methods
| 150 | Monitoring data more than 5 years old |
| 200 | Physical/Chemical Monitoring |
| 315 | Regional reference site approach |
| 320 | Benthic macroinvertebrate surveys |
| 420 | Indicator bacteria monitoring |