South Skunk River IA 03-SSK-927
from the Highway 63 bridge north of Oskaloosa (S25 T76N R16W Mahaska Co.) to confluence with Elk Cr. in NE 1/4 S19 T77N R17W Mahaska 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 8:54:52 AM
- Updated
- 1/13/2022 11:35:06 AM
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 C use was assessed as "fully supported" based on water quality monitoring data. All other designated uses were "not assessed."
Data Sources: Data Source Data Source ID Data Type Data Age Site ID Site Name Site Description Iowa DNR 6 WQ CY 2018-2020 10620001 South Skunk River near Oskaloosa
Iowa DNR 6 BIO See Below 945 South
Skunk River Oskaloosa 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 10620001 6 8/8/8 327 327 192 YES 3 / 3 5 / 3 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 10620001 6 36 / 3 6.8 8.6 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 10620001 6 Ammonia 36 / 3 0.02 0.74 0.07 NA 0 / 0 7 NO Monitored Full 10620001 6 Chloride 36 / 3 9.6 50 23.6 NA 0 / 0 7 NO Monitored Full 10620001 6 Dissolved Oxygen 36 / 3 5.4 13.7 10.1 0 NA / NA 7 NO Monitored Full 10620001 6 pH 36 / 3 6.8 8.6 8.2 0 NA / NA 7 NO Monitored Full 10620001 6 Sulfate 36 / 3 11 66 30 0 NA / NA 7 NO Monitored Full 10620001 6 Temperature 36 / 3 0 26.4 11.6 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 10620001 6 Aluminum 14 / 3 3.5 1 0.8 0 / 0 NO Monitored Full 10620001 6 Arsenic 13 / 3 3.4 1.7 1.4 0 / 0 NO Monitored Full 10620001 6 Cadmium 13 / 3 0.07 0.03 0.02 0 / 0 NO Monitored Full 10620001 6 Chromium 13 / 3 1.3 0.9 1 0 / 0 NO Monitored Full 10620001 6 Lead 13 / 3 0.99 0.2 0.11 0 / 0 NO Monitored Full 10620001 6 Nickel 13 / 3 4.4 3.1 3.2 0 / 0 NO Monitored Full 10620001 6 Silver 13 / 3 0.025 0.025 0.025 0 / 0 NO Monitored Full 10620001 6 Zinc 13 / 3 4.3 2.1 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 945 9/17/19 1635 47f MS Floating Art Sub 44 Fair 51 Fail 945 9/6/16 1635 47f MS Floating Art Sub 51 Fair 51 Pass Overall: Community Assessment Type Assessment Result Support Level IR Category Reason Benthic
Macroinvertebrates Evaluated Fail (1/2) Not Assessment
was evaluated because the drainage area of the site used for Overall Evaluated Fail WINOFI 3bu the assessment was
greater than the calibrated range. Site ID Data Source ID Parameter Name # Samples / # Years Minimum Value Maximum Value Mean Value Median Value # Violations Violates Significantly >10% Rule? Assessment Type Support Level 10620001 6 Chloride 36 / 3 9.6 50 23.6 22 0 NO Monitored Full 10620001 6 Inorganic nitrogen (nitrate and nitrite) 36 / 3 0.05 9.8 4.6 4.7 0 NO Monitored Full 10620001 6 pH 36 / 3 6.8 8.6 8.2 8.3 0 NO Monitored Full Class C - Toxic
Parameters: 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 10620001 6 Alachlor 11 / 3 0.05 0.05 0.05 11 NO Monitored Full 10620001 6 Atrazine 11 / 3 0.4 0.2 0.05 6 NO Monitored Full 10620001 6 Simazine 11 / 3 0.05 0.05 0.05 11 NO Monitored Full
Class BWW1 - Biological Sampling:
Benthic Macroinvertebrates:
Class C - Conventional Parameters:
Class HH - No Data