Silver Creek IA 01-TRK-192
mouth (S16 T94N R5W Clayton Co.) to confluence with unnamed tributary in S32 T95N R5W Clayton Co.
- Cycle
- 2020
- Release Status
- Final
- Overall IR
- 5 - Water is impaired or threatened and a TMDL is needed.
- Trend
- Unknown
- Created
- 8/21/2020 8:38:28 AM
- Updated
- 10/15/2020 12:44:34 PM
The presumptive Class A1 use remains assessed as “not supported” due to levels of indicator bacteria (E. coli) that exceeded state water quality criteria. The Class BWW2 use remains assessed as "partially supported" based on biological sampling data and "not supported" due to historic violations of the dissolved oxygen state water quality criterion. Note: The Iowa DNR TMDL for biology, sediment, and ammonia for this segment of Silver Creek was approved by U.S. EPA in July 2012. Because not all the impairments identified for this assessment segment were covered by the TMDL (i.e., indicator bacteria and dissolved oxygen), this segment remains impaired and in IR Category 5.
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 11220014 Silver
Creek at 172 ST Site
SC04/SiCR1 Iowa
DNR 6 BIO See
Below 571 Silver
Creek Monona–
SiCR1 Iowa
DNR 6 BIO See
Below 973 Silver
Creek Luana Presumptive
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 11220014 6 24 / 3 1559 1667 699 Yes 16 67% Yes Evaluated Not 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 11220014 6 22 / 3 8.8 8.29 8.26 0 0% No Evaluated Full Class
BWW2 - 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 11220014 6 Ammonia 14 / 2 1.1 0.31 0.12 0 / 0 0% / 0% No Evaluated Full 11220014 6 Chloride 19 / 3 59 35 33 NA / 0 NA / 0% No Evaluated Full 11220014 6 Dissolved Oxygen 24 / 3 12 8 9 3 / NA 12% / NA No Evaluated Full 11220014 6 pH 22 / 3 8.8 8.29 8.26 0 / 0 0% / 0% No Evaluated Full 11220014 6 Temperature 24 / 3 24.4 15 16.6 NA / 0 NA / 0% No Evaluated Full Although results of monitoring for the 2016 IR cycle did not suggest an impairment of the Class BWW2 aquatic life use due to dissolved oxygen, this impairment remains in effect because additional dissolved oxygen monitoring has not been conducted in this segment and removal of an impairment requires two consecutive fully supported cycles. Class
BWW2 - Biological Sampling: Benthic
Macroinvertebrates: BioNet Site ID Date Drainage Area (mi2) Ecoregion Major Drainage/ Thermal BM Sample Gear BMIBI score BMIBI Class 52b BMIBI BIT BMIBI Pass/ Fail 571 8/20/18 27 52b MS/WW Surb 61 Good 61 Pass 571 8/14/14 27 52b MS/WW Surb 55 Fair 61 Fail 973 8/14/14 17 52b MS/WW Surb 44 Fair 61 Fail Fish: BioNet Site ID Date Drainage Area (mi2) Ecoregion Major Drainage/ Thermal Riffle Stream? FIBI score FIBI Class 52b FIBI BIT FIBI Pass/ Fail 571 8/20/18 27 52b MS/WW NA 44 Fair 52 Fail 571 8/14/14 27 52b MS/WW NA 46 Fair 52 Fail 973 8/14/14 17 52b MS/WW NA 41 Fair 52 Fail Overall: Community Assessment Type Assessment Result Support Level Earned IR Category Actual IR Category Reason Benthic
Macroinvertebrates Monitored Fail (1/3) Partial Fish Monitored Fail (0/3) Partial Overall Monitored Fail Partial 5bv 4a Assessment
is monitored because the samples used to complete the assessment were
collected in the last five years. Impairment is covered by 2012 TMDL.