South Skunk River IA 03-SSK-934
from the Ames Water Works dam in River Valley Park at Ames (S36 T84N R24W Story Co.) to the Co. Rd. at north line of S6 T85 R23W Story Co (approximately 1 mile NNE of Story City)
- 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 11:54:26 AM
- Updated
- 1/7/2022 11:36:54 AM
Assessment Summary
The Class A1 use was assessed as “not supported” due to levels of indicator bacteria that violated state water quality criteria. The Class BWW1 use was assessed as "not supported" based on biological sampling data. All other designated uses were "not assessed."
Assessment Explanation
Data
Sources: Data Source Data Source ID Data Type Data Age Site ID Site Name Site Description Iowa DNR 6 WQ CY 2012-2014 10850003 South Skunk River Upstream of Ames (US1) Iowa DNR 6 BIO See Below 38 South Skunk River Ames Iowa DNR 6 BIO See Below 972 South Skunk River Ames – US1 Site ID Data Source ID # Samples / # Years 2012 Geometric Mean 2013 Geometric Mean 2014 Geometric Mean Annual Geometric Mean Violation # Violations % Violations Significantly >10% Violations Assessment Type Support Level 10850003 6 22 / 3 46 94 223 Yes 7 32% Yes Evaluated Not Site ID Data Source ID # Samples / # Years Maximum Value Mean Value Median Value # Violations % Violations Significantly >10% Violations Assessment Type Support Level 10850003 6 33 / 3 8.6 8.1 8.1 0 0% No Evaluated Full Site ID Data Source ID Parameter Name # Samples / # Years Maximum Value Mean Value Median Value # Acute / Chronic Violations % Acute/ Chronic Violations Significantly >10% Violations Assessment Type Support Level 10850003 6 Ammonia 33 / 3 1.7 0.15 0.05 0 / 0 0% / 0% No Evaluated Full 10850003 6 Chloride 33 / 3 100 43 35 0 / 0 0% / 0% No Evaluated Full 10850003 6 Dissolved oxygen 33 / 3 16.2 10.7 10.2 NA / 0 NA / 0% No Evaluated Full 10850003 6 pH 33 / 3 8.6 8.1 8.1 0 / NA 0% / NA No Evaluated Full 10850003 6 Sulfate 33 / 3 110 46 41 0 / NA 0% / NA No Evaluated Full 10850003 6 Temperature 33 / 3 27.5 12 12.4 0 / 0 0% / 0% No Evaluated Full Benthic
Macroinvertebrates: BioNet Site ID Date Drainage Area (mi2) Ecoregion Major Drainage/Thermal BM Sample Gear BMIBI score BMIBI Class 47b BMIBI BIT BMIBI Pass/Fail 38 8/31/17 254 47b MS/WW Surb 58 Good 62 Fail 972 9/4/14 315 47b MS/WW Hess 53 Fair 62 Fail 972 9/4/14 315 47b MS/WW ArtSub 38 Fair 62 Fail Fish: BioNet Site ID Date Drainage Area (mi2) Ecoregion Major Drainage/Thermal Riffle Stream? FIBI score FIBI Class 47b FIBI BIT FIBI Pass/Fail 38 8/31/17 254 47b MS/WW No 70 Good 32 Pass 38 7/18/13 254 47b MS/WW No 13 Poor 32 Fail Community Assessment Type Assessment Result Support Level IR Category Reason Benthic Macroinvertebrates Evaluated Fail (0/3) Not Fish Evaluated Fail (1/2) Not Assessment
was evaluated because it included samples Overall Evaluated Fail Not 5bv not
collected in the last five years. The
Class BWW1 use previously resided in IR Category 3b based on the assessment
developed for the 2011 fish kill. Because no additional fish kills were
reported in this segment for at least 10 years post fish kill (2021), the IR
Category for the fish kill assessment was changed from 3b to 3a (not assessed).
DNR believes that any impact from the fish kill from which the impairment was
based has likely dissipated. Details
about the 2011 fish kill can be found here: https://programs.iowadnr.gov/fishkill/Events/832.
Class A1 - Indicator Bacteria:
Class A - pH:
Class BWW1 - Conventional Parameters:
Class BWW1 - Biological Sampling:
Overall:
Class BWW1 - Fish kill Assessment:
Class HH - No Data
Assessment Key Dates
7/18/2013 | Biological Monitoring |
9/4/2014 | Biological Monitoring |
1/10/2012 | Fixed Monitoring Start Date |
9/4/2014 | Fixed Monitoring End Date |
8/31/2017 | Biological Monitoring |
Methods
150 | Monitoring data more than 5 years old |
210 | Fixed station physical/chemical monitoring (conventional pollutants only) |
315 | Regional reference site approach |
320 | Benthic macroinvertebrate surveys |
330 | Fish surveys |
420 | Indicator bacteria monitoring |