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
- 2020
- Release Status
- Final
- Data Collection Period
- Overall IR Category
- 5 - Water is impaired or threatened and a TMDL is needed.
- Trend
- Unknown
- Created
- 6/9/2020 10:45:37 AM
- Updated
- 10/15/2020 11:56:21 AM
The Class A1 use remains assessed as “partially supported” due to levels of indicator bacteria that violate state water quality criteria. The Class BWW1use was assessed as "partially supported" based on biological sampling data and on a fish kill investigation. All other designated uses were "not assessed".
Sources of
Data: 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 Class A1 -
Indicator Bacteria: 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 Partial Class A - pH: 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 Class BWW1 -
Conventional Parameters: 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 Class BWW1 - Biological Sampling: 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 Overall: Community Assessment Type Assessment Result Support Level Earned IR Category Actual IR Category Reason Benthic
Macroinvertebrates Monitored Fail (0/3) Partial Fish Evaluated Fail (1/2) Partial Overall Monitored Fail Partial 5bv 5bv Assessment is monitored
because it included all BM samples were collected in the last five years. Class BWW1 - Fishkill Assessment: The Class BWW1 use previously resided in Category 4d based on the assessment developed for the 2011 fish kill. Because no additional fish kills were reported in this segment for at least five years post fish kill (2016), the Category for the fish kill assessment was changed from 4d to 3b (potentially impaired). DNR believes that any impact from the fish kill from which the impairment was based has likely dissipated. If no additional fish kills are reported in the segment for an additional five-year period (2021), the Category will be changed from 3b to 3a (water not assessed). Details about the 2011 fish kill can be found here:https://programs.iowadnr.gov/fishkill/Events/832. Class HH - No data