Rock River IA 06-BSR-1534
mouth (S1 T95N R48W Sioux Co.) to confluence with Little Rock R. in S35 T98N R46W Lyon 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
- Stable
- Created
- 6/18/2020 12:10:37 PM
- Updated
- 10/13/2020 2:34:16 PM
| Cycle Added | Class | Cause | Data Source | Rationale |
|---|---|---|---|---|
| 2004 | Class BWW1 | Fish Kill: Caused By Animal Waste | Biological monitoring: Iowa DNR fish kill follow-up | New data: recovery of fish community from pollutant-caused fish kill |
Assessment Summary
The Class A1 use remains assessed as "partially supported" due to levels of indicator bacteria (E. coli) that violated state water quality criteria. The Class BWW1 use was assessed as “partially supported” based on biological sampling data and on violations of the chronic water quality criteria for selenium. The previous 5b Class BWW1 impairment based on a 2002 fish kill was de-listed based on 2003 fish sampling data. The Class HH use was assessed as "fully supported" based on water quality monitoring data.
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 2014-2016, CY 2016-2018 10840001 Rock River near Hawarden Iowa DNR 6 BIO See Below 365 Rock River Rock Valley – REMAP #244 Iowa DNR 6 BIO See Below 842 Rock River Hawarden Class
A1 - Indicator Bacteria: Site ID Data Source ID # Samples / # Years 2014 Geometric Mean 2015 Geometric Mean 2016 Geometric Mean Annual Geometric Mean Violation # Violations % Violations Significantly >10% Violations Assessment Type Support Level 10840001 6 24 / 3 149 127 681 Yes 14 58% 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 10840001 6 34 / 3 8.6 8.2 8.3 0 0% 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 10840001 6 Ammonia 34 / 3 1.9 0.11 0.02 0 / 0 0% / 0% No Monitored Full 10840001 6 Chloride 36 / 3 32 28 28 0 / 0 0% / 0% No Monitored Full 10840001 6 Dissolved oxygen 36 / 3 14.2 10.2 10.3 NA / 0 NA / 0% No Monitored Full 10840001 6 pH 34 / 3 8.6 8.2 8.3 0 / NA 0% / NA No Monitored Full 10840001 6 Sulfate 36 / 3 120 87 88 0 / NA 0% / NA No Monitored Full 10840001 6 Temperature 36 / 3 27.7 12.4 10.4 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 10840001 6 Aluminum 9 / 2 5.3 1.84 0.94 0 / 0 0% / 0% No Evaluated Full 10840001 6 Arsenic 9 / 2 3.5 2.2 2.1 0 / 0 0% / 0% No Evaluated Full 10840001 6 Cadmium 9 / 2 0.025 0.025 0.025 0 / 0 0% / 0% No Evaluated Full 10840001 6 Chromium 9 / 2 5.5 1.41 0.9 0 / 0 0% / 0% No Evaluated Full 10840001 6 Copper 9 / 2 7.3 1.7 1 0 / 0 0% / 0% No Evaluated Full 10840001 6 Lead 9 / 2 0.5 0.138 0.08 0 / 0 0% / 0% No Evaluated Full 10840001 6 Nickel 9 / 2 6.1 3.2 3 0 / 0 0% / 0% No Evaluated Full 10840001 6 Selenium 9 / 2 6.7 4.3 4 0 / 2 0% / 22% Yes Evaluated Partial 10840001 6 Zinc 9 / 2 3.9 2.1 2.2 0 / 0 0% / 0% No Evaluated Full Class
BWW1 – Fish kill Follow-Up Assessment: BioNet Site ID Stream Name Site Type Ecoregion Sample Date Fish per mile REMAP 25 %
fish/mile >REMAP 25
% fish/mile? 2000 305(b) fish taxa
present 2000 305(b) fish taxa
present % 365 Rock River Wadeable 47a 8/6/2003 1493 524 Yes (Pass) 7/9 78% (Pass) The
Class BWW1 use previously resided in Category 5b based on a 2002 fish kill.
This segment’s fish community was sampled in 2003 as part of the DNR fish
kill follow-up sampling program. The results from this follow-up sampling and
comparison to ecoregion averages suggest that the fish community of this
segment is similar to non-fish kill impacted streams. Based on the results of
the fish kill follow-up sampling, the Category for the fish kill assessment
was changed from 5b to 3a (water not assessed). Class
BWW1 - Biological Sampling: Benthic
Macroinvertebrates: BioNet Site ID Date Drainage Area (mi2) Ecoregion Major Drainage/Thermal BM Sample Gear BMIBI score BMIBI Class 47a BMIBI BIT BMIBI Pass/ Fail 842 10/7/14 1680 47a MO/WW ArtSub 42 Fair 54 Fail 842 9/4/13 1680 47a MO/WW ArtSub 21 Poor 54 Fail Overall: Community Assessment Type Assessment Result Support Level Earned IR Category Actual IR Category Reason Benthic
Macroinvertebrates Evaluated Fail (0/2) Partial 3bu 3bu Assessment
is evaluated because the drainage area of the sample site was larger than the
calibrated range. 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 10840001 6 Cadmium 9 / 2 0.025 0.025 0.025 9 No Evaluated Full 10840001 6 Chromium 9 / 2 5.5 1.41 0.9 0 No Evaluated Full 10840001 6 Copper 9 / 2 7.3 1.7 1 0 No Evaluated Full 10840001 6 Nickel 9 / 2 6.1 3.2 3 0 No Evaluated Full 10840001 6 Selenium 9 / 2 6.7 4.3 4 0 No Evaluated Full 10840001 6 Zinc 9 / 2 3.9 2.1 2.2 0 No Evaluated Full
Assessment Key Dates
| 1/8/2014 | Fixed Monitoring Start Date |
| 12/7/2016 | Fixed Monitoring End Date |
| 8/6/2003 | Biological Monitoring |
| 9/4/2013 | Biological Monitoring |
| 10/7/2014 | Biological Monitoring |
| 1/5/2016 | Fixed Monitoring Start Date |
| 12/5/2018 | Fixed Monitoring End Date |
Methods
| 150 | Monitoring data more than 5 years old |
| 230 | Fixed station physical/chemical (conventional plus toxic pollutants) |
| 315 | Regional reference site approach |
| 320 | Benthic macroinvertebrate surveys |
| 330 | Fish surveys |
| 420 | Indicator bacteria monitoring |