Beaver Creek IA 04-UDM-1233
mouth (S17 T79N R24W Polk Co.) to the Polk/Dallas county line (west line S18 T80N R25W Polk 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
- 9/15/2020 1:19:45 PM
- Updated
- 11/12/2020 11:55:33 AM
| Cycle Added | Class | Cause | Data Source | Rationale |
|---|---|---|---|---|
| 2016 | Class BWW2 | Biological: low aquatic macroinvertebrate IBI | Biological monitoring: Iowa DNR WQMA | New data: recovery of fish/invertebrate community |
Assessment Summary
The presumptive Class A1 use was assessed as "not supported" due to levels of indicator bacteria (E. coli) that violated state water quality criteria. The Class BWW2 use was assessed as "fully supported" based on biological sampling data and water quality monitoring data. The "fully supported" assessment of the Class BWW2 use results in a de-listing of a previous Category 5bv impairment.
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 10770001 Beaver Creek near Grimes Iowa DNR 6 BIO See Below 910 Beaver Creek Grimes Presumptive 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 10770001 6 24 / 3 677.96 487.52 1465.3 Yes 20 83% Yes Monitored Not Presumptive 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 10770001 6 34 / 3 8.5 8.2 8.3 0 0% No Monitored 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 10770001 6 Ammonia 34 / 3 0.99 0.07 0.02 0 / 0 0% / 0% No Monitored Full 10770001 6 Chloride 36 / 3 86 30 23 0 / 0 0% / 0% No Monitored Full 10770001 6 Dissolved oxygen 36 / 3 17.3 10.6 10.4 NA / 0 NA / 0% No Monitored Full 10770001 6 pH 34 / 3 8.5 8.2 8.3 0 / NA 0% / NA No Monitored Full 10770001 6 Sulfate 36 / 3 250 42.4 24.5 0 / NA 0% / NA No Monitored Full 10770001 6 Temperature 36 / 3 28 13 12 0 / 0 0% / 0% No Monitored Full Class BWW2 - 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 10770001 6 Aluminum 9 / 2 5.9 1.532 0.43 0 / 0 0% / 0% No Evaluated Full 10770001 6 Arsenic 9 / 2 2.8 2 1.7 0 / 0 0% / 0% No Evaluated Full 10770001 6 Cadmium 9 / 2 0.28 0.059 0.025 0 / 0 0% / 0% No Evaluated Full 10770001 6 Chromium 9 / 2 3.2 1.21 1 0 / 0 0% / 0% No Evaluated Full 10770001 6 Copper 9 / 2 3.8 1.6 1.4 0 / 0 0% / 0% No Evaluated Full 10770001 6 Lead 9 / 2 0.22 0.083 0.09 0 / 0 0% / 0% No Evaluated Full 10770001 6 Nickel 9 / 2 4.7 3.2 3.3 0 / 0 0% / 0% No Evaluated Full 10770001 6 Selenium 9 / 2 3.1 1.89 1.7 0 / 0 0% / 0% No Evaluated Full 10770001 6 Zinc 9 / 2 5.5 2.23 1.5 0 / 0 0% / 0% No Evaluated Full Class BWW2 - 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 910 8/31/16 358 47b MS/WW Float ArtSub 67 Good 62 Pass 910 9/16/15 358 47b MS/WW Float ArtSub 67 Good 62 Pass Overall: Community Assessment Type Assessment Result Support Level Earned IR Category Actual IR Category Reason Benthic Macroinvertebrates Monitored Pass (2/2) Full 1 1 Assessment is monitored because all samples
were collected in the last five years.
Assessment Key Dates
| 1/6/2016 | Fixed Monitoring Start Date |
| 12/6/2018 | Fixed Monitoring End Date |
| 9/16/2015 | Biological Monitoring |
| 8/31/2016 | Biological Monitoring |
Methods
| 230 | Fixed station physical/chemical (conventional plus toxic pollutants) |
| 315 | Regional reference site approach |
| 320 | Benthic macroinvertebrate surveys |
| 420 | Indicator bacteria monitoring |