Shell Rock River IA 02-SHL-783
from south corporate limit of Shell Rock (S12 T91N R15W Butler Co.) to confluence with Flood Cr. in S27 T93N R16W Butler Co.
- 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
- 9/4/2020 10:13:52 AM
- Updated
- 10/14/2020 1:38:49 PM
Assessment Summary
The Class A1 use was assessed as "partially supported" based on levels of indicator bacteria (E. coli) that exceeded state water quality criteria. The Class BWW1 use was assessed as "fully supported" based on biological sampling data and water quality monitoring data. The Class HH use remains assessed as "partially supported" based on fish tissue sampling data and due to the existence of a one meal per week fish consumption advisory for mercury.
Assessment Explanation
Sources
of Data: Data Source Data Source ID Data Type Data Age Site ID Site Name Site Description Iowa DNR 6 WQ CY 2016-2018 10120001 Shell Rock River at Shell Rock Iowa DNR 6 BIO See Below 843 Shell Rock River Shell Rock Iowa DNR 6 FT See Below 68 Shell Rock River W of Clarksville Shell Rock Class
A1 - Indicator Bacteria: Site ID Data Source ID # Samples / # Years 2016 Geometric Mean 2017 Geometric Mean 2018 Geometric Mean Annual Geometric Mean Violation # Violations % Violations Significantly >10% Violations Assessment Type Support Level 10120001 6 22 / 3 129.04 81.8 263 Yes 6 27% Yes Monitored Partial Class
A1 - pH: Site ID Data Source ID # Samples / # Years Maximum Value Mean Value Median Value # Violations % Violations Significantly >10% Violations Assessment Type Support Level 10120001 6 36 / 3 9.3 8.2 8.2 1 3% No Monitored 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 10120001 6 Ammonia 36 / 3 0.77 0.06 0.02 0 / 0 0% / 0% No Monitored Full 10120001 6 Chloride 36 / 3 29 19.5 19 0 / 0 0% / 0% No Monitored Full 10120001 6 Dissolved oxygen 36 / 3 14.5 11 11 NA / 0 NA / 0% No Monitored Full 10120001 6 pH 36 / 3 9.3 8.2 8.2 1 / NA 3% / NA No Monitored Full 10120001 6 Sulfate 36 / 3 56 31 27 0 / NA 0% / NA No Monitored Full 10120001 6 Temperature 36 / 3 23.8 11.2 10.6 0 / 0 0% / 0% 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 % Acute/ Chronic Violations >1 Acute / Chronic Violation Assessment Type Support Level 10120001 6 Aluminum 9 / 2 0.85 0.32 0.28 0 / 0 0% / 0% No Evaluated Full 10120001 6 Arsenic 9 / 2 2 1.34 1.2 0 / 0 0% / 0% No Evaluated Full 10120001 6 Cadmium 9 / 2 0.025 0.025 0.025 0 / 0 0% / 0% No Evaluated Full 10120001 6 Chromium 9 / 2 1.2 0.88 0.88 0 / 0 0% / 0% No Evaluated Full 10120001 6 Copper 9 / 2 2.4 0.85 0.7 0 / 0 0% / 0% No Evaluated Full 10120001 6 Lead 9 / 2 0.09 0.051 0.06 0 / 0 0% / 0% No Evaluated Full 10120001 6 Nickel 9 / 2 3.1 2.4 2.4 0 / 0 0% / 0% No Evaluated Full 10120001 6 Selenium 9 / 2 2.1 1.32 1.3 0 / 0 0% / 0% No Evaluated Full 10120001 6 Zinc 9 / 2 2.6 1.48 1.2 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 47c BMIBI BIT BMIBI Pass/ Fail 843 8/15/16 1730 47c MS/WW Hess 81 Excellent 70 Pass 843 9/8/14 1730 47c MS/WW Float ArtSub 65 Good 52 Pass 843 9/8/14 1730 47c MS/WW Hess 65 Good 70 Fail Overall Assessment: Community Assessment Type Assessment Result Support Level Earned IR Category Actual IR Category Reason Benthic Macroinvertebrates Evaluated Pass (2/3) Full 1 1 Assessment is evaluated
because the drainage area of the sample site is larger than calibrated range. Class HH – Fish Tissue
Sampling: Site ID Date Species Name Biopart # in sample chlordane result chlordane violation (>0.6)? PCBs result PCBs violation (>0.2)? Hg result Hg violation (>0.3)? Assessment Type Support Level 68 8/2/2012 walleye plug 3 0.285 No Evaluated Full 68 8/23/2011 walleye plug 4 0.753 Yes Evaluated Partial 68 8/23/2011 common carp fillet 5 <0.03 No <0.09 No 0.206 No Evaluated Full Follow-up monitoring
was conducted in 2012 to better define the level of mercury in Shell Rock
River fish and to provide information for any changes needed to the
consumption advisory. Results showed that the average level of mercury in
tissue samples from three Walleye was just below the consumption advisory
threshold of 0.3 ppm (ave = 0.285, sd = 0.078). A one meal/week consumption advisory for mercury exists on this segment of the Shell Rock River – seeIowa Consumption Advisories Because a one meal per
week fish consumption advisory covers this waterbody, the fish consumption
uses are assessed as “partially supported.” Class
HH-F - 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 10120001 6 Cadmium 9 / 2 0.025 0.025 0.025 9 No All Non-Detect Full 10120001 6 Chromium 9 / 2 1.2 0.88 0.88 0 No Evaluated Full 10120001 6 Copper 9 / 2 2.4 0.85 0.7 0 No Evaluated Full 10120001 6 Nickel 9 / 2 3.1 2.4 2.4 0 No Evaluated Full 10120001 6 Selenium 9 / 2 2.1 1.32 1.3 0 No Evaluated Full 10120001 6 Zinc 9 / 2 2.6 1.48 1.2 0 No Evaluated Full
Assessment Key Dates
| 8/23/2011 | Fish Tissue Monitoring |
| 8/25/2016 | Biological Monitoring |
| 1/7/2016 | Fixed Monitoring Start Date |
| 12/11/2018 | Fixed Monitoring End Date |
| 8/2/2012 | Fish Tissue Monitoring |
| 9/8/2014 | Biological Monitoring |
Methods
| 230 | Fixed station physical/chemical (conventional plus toxic pollutants) |
| 260 | Fish tissue analysis |
| 315 | Regional reference site approach |
| 320 | Benthic macroinvertebrate surveys |
| 420 | Indicator bacteria monitoring |