Coldwater Creek IA 01-UIA-280
mouth (S32 T100N R9W Winneshiek Co.) to north line of S31 T100N R9W Winneshiek Co.
- Cycle
- 2026
- Current Phase
- Public Comment
- Overall IR
- 5 - Water is impaired or threatened and a TMDL is needed.
- Trend
- Stable
- Created
- 10/27/2025 3:09:30 PM
- Updated
- 12/23/2025 10:19:07 AM
The presumptive Class A1 use and the Class A2 uses remain assessed as “not supported” due to levels of indicator bacteria (E. coli) that exceeded state water quality criteria. The Class BCW1 use was assessed as "fully supported" based on biological sampling data and on the trout reproduction in Iowa streams summary prepared by the DNR Fisheries Bureau. 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 BIO/WQ See Below 18 Coldwater Creek Coldwater Creek SWMA
- Bluffton Iowa DNR 6 WQ CY 2012-2014 191910003 Coldwater Creek Site 9 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 191910003 19 21 / 3 131 188 1231 Yes 9 43% Yes Evaluated Not 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 191910003 19 21 / 3 131 188 1231 Yes 4 19% No Evaluated Not Class BCW1 - Biological Sampling: Benthic Macroinvertebrates: Site ID Date Drainage Area (mi2) Ecoregion Major Drainage BM Sample Gear CBI score CBI Class CBI BIT CBI Pass/Fail 18 7/24/24 22.4 52b MS Hess 53 NA 60 Fail 18 8/4/20 22.4 52b MS Hess 62 NA 60 Pass 18 9/21/16 22.4 52b MS Hess 61 NA 60 Pass 18 7/19/16 22.4 52b MS Hess 70 NA 60 Pass Community Assessment Type Assessment Result Support Level IR Category Reason Benthic
Macroinvertebrates Evaluated Pass (3/4) Full Assessment was evaluated because the
assessment used samples Overall Evaluated Pass Full 1 collected outside a recent five-year period
to complete the assessment. Site ID Data Source ID # Days Monitoring (2016) DO Criteria Type # 2016 violations/Violations needed for impairment Violates Annual Significantly >10% Rule? Assessment Type Support Level 24 hr 1/7 No 18 6 39 16 hr 0/7 No Evaluated Full
Aquatic Life Use - Trout Natural Reproduction
Based on the latest trout reproduction in Iowa streams summary prepared by the DNR Fisheries Bureau, the aquatic life use was assessed as "fully supported." According to the summary, a portion, or all, of this assessment unit was placed in both Category I: streams that exhibit consistent natural reproduction and maintain a wild population of one or more trout species without any stocking and in Category II: streams that exhibit recent but inconsistent reproductive success of one or more trout species.
Presumptive Class A1 - Indicator Bacteria: 2012-2014
Class A2 - Indicator Bacteria: 2012-2014
Class HH - No Data
Overall:
Class BCW1 - Continuous DO Monitoring: