South Skunk River IA 03-SSK-931
from confluence with Indian Creek (S32 T80N R20W Jasper Co.) to outfall of Ames wastewater treatment plant in SW 1/4 S32 T83N R23W Story 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
- 12/22/2021 11:52:54 AM
- Updated
- 12/27/2021 9:02:49 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 BWW2 use was assessed as "fully supported" based on biological sampling data and 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 2018-2020 10850002 South Skunk River near Cambridge (DS1)
Iowa DNR 6 BIO See Below 286 South
Skunk River Cambridge 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 10850002 6 7/6/8 564 208 144 YES 5 / 3 1 / NA 4 / 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 10850002 6 36 / 3 7 8.4 8 0 7 NO Monitored Full Class BWW2 -
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 10850002 6 Ammonia 35 / 3 0.025 1.3 0.1 NA 0 / 0 7 NO Monitored Full 10850002 6 Chloride 36 / 3 12 81 33 NA 0 / 0 7 NO Monitored Full 10850002 6 Dissolved Oxygen 36 / 3 7.3 13.8 10.1 0 NA / NA 7 NO Monitored Full 10850002 6 pH 36 / 3 7 8.4 8 0 NA / NA 7 NO Monitored Full 10850002 6 Sulfate 36 / 3 9.9 95 37.2 0 NA / NA 7 NO Monitored Full 10850002 6 Temperature 35 / 3 0.7 27.2 12.3 0 NA / NA 7 NO Monitored Full Class BWW2 -
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 10850002 6 Aluminum 14 / 3 4.5 1.2 0.4 0 / 0 NO Monitored Full 10850002 6 Arsenic 13 / 3 2.3 1.6 1.5 0 / 0 NO Monitored Full 10850002 6 Cadmium 13 / 3 0.09 0.04 0.02 0 / 0 NO Monitored Full 10850002 6 Chromium 13 / 3 1.4 0.9 1.1 0 / 0 NO Monitored Full 10850002 6 Lead 13 / 3 0.27 0.16 0.16 0 / 0 NO Monitored Full 10850002 6 Nickel 13 / 3 4.9 3.5 3.2 0 / 0 NO Monitored Full 10850002 6 Silver 13 / 3 0.025 0.025 0.025 0 / 0 NO Monitored Full 10850002 6 Zinc 13 / 3 12 3.6 2.3 0 / 0 NO Monitored Full Site ID Date Drainage Area (mi2) Ecoregion Major Drainage BM Sample Gear BMIBI score BMIBI Class 47b BMIBI BIT BMIBI Pass/Fail 286 7/23/20 605 47b MS Floating Art Sub 66 Good 62 Pass 286 8/17/16 605 47b MS Floating Art Sub 55 Fair 62 Fail 286 7/21/15 605 47b MS Floating Art Sub 75 Good 62 Pass Overall: Community Assessment Type Assessment Result Support Level IR Category Reason Benthic
Macroinvertebrates Evaluated Pass (2/3) Full Assessment was evaluated
because the drainage area of the site Overall Evaluated Pass Full 1 was greater than the
calibrated range.
Class BWW2 - Biological Sampling:
Benthic Macroinvertebrates:
Assessment Key Dates
7/23/2020 | Biological Monitoring |
1/4/2018 | Fixed Monitoring Start Date |
12/2/2020 | Fixed Monitoring End Date |
7/21/2015 | Biological Monitoring |
8/17/2016 | Biological Monitoring |
Methods
230 | Fixed station physical/chemical (conventional plus toxic pollutants) |
315 | Regional reference site approach |
320 | Benthic macroinvertebrate surveys |
420 | Indicator bacteria monitoring |