Norfolk Creek IA 01-YEL-444
mouth (S6 T96N R5W Allamakee Co.) to confluence with Teeple Cr. in S24 T97N R6W Allamakee Co.
- Assessment Cycle
- 2024
- Release Status
- Pending
- Data Collection Period
- Overall IR Category
- 4 - Water is impaired or threatened and a TMDL has been completed or is not needed.
- Trend
- Unknown
- Created
- 11/1/2023 8:13:49 AM
- Updated
- 2/6/2024 7:40:00 AM
| Cycle Added | Class | Cause | Data Source | Rationale |
|---|---|---|---|---|
| 2006 | Class BCW1 | Organic Enrichment: Low Dissolved Oxygen | Ambient monitoring: Iowa DNR-rivers | New data: WQ improvement (chemical / physical / bacterial) |
Assessment Summary
The presumptive Class A1 use was assessed as “not supported” due to levels of indicator bacteria (E. coli) that exceeded state water quality criteria. The Class A2 use was assessed as “fully supported” based on pH monitoring data. The Class BCW1 use was assessed as "fully supported" based on water quality monitoring and on the trout reproduction in Iowa streams summary prepared by the DNR Fisheries Bureau. All other designated uses were “not assessed.” Note: A TMDL for the bacterial impairment for streams in the Yellow River basin was prepared by Iowa DNR in 2012 and was approved by U.S. EPA in February 2013. Due to completion of the TMDL, the Integrated Report category for the Class A1 recreational use was changed from 5p (impaired; TMDL needed) to 4a (impaired; TMDL approved).
Assessment Explanation
Data Sources: Data Source Data Source ID Data Type Data Age Site ID Site
Name Site
Description Iowa DNR 6 WQ CY 2006-2008, CY 2021-2022 15030008 Norfolk
Creek at Co. Rd. W48
Site ID Data Source ID # Samples / # Years 2006 Geometric Mean 2007 Geometric Mean 2008 Geometric Mean Annual Geometric Mean Violation # Violations % Violations Significantly >10% Violations Assessment Type Support Level 15030008 6 37 / 3 223 467 415 Yes 17 46% Yes Evaluated Not Site ID Data Source ID # Samples / # Years Minimum Value Maximum Value Mean Value # Violations Violations needed for impairment Violates Significantly >10% Rule? Assessment Type Support Level 15030008 6 10 / 2 7.18 8.13 7.83 0 3 NO Mon Full Site ID Data Source ID Parameter Name # Samples / # Years Minimum Value Maximum Value Mean Value # Violations # Acute / Chronic Violations Violations needed for impairment Violates Significantly >10% Rule? Assessment Type Support Level 15030008 6 Dissolved Oxygen 10 / 2 6.65 12.31 9.27 1 NA / NA 3 NO Mon Full 15030008 6 pH 10 / 2 7.18 8.13 7.83 0 NA / NA 3 NO Mon Full 15030008 6 Temperature 10 / 2 6.10 20.04 14.06 1 NA / NA 3 NO Mon Full Based on the January 2024 summary of trout reproduction in Iowa streams
prepared by the DNR Fisheries Bureau, the Class BCW1 coldwater aquatic life use
Norfolk Creek was assessed as "fully supported." According to the
updated summary, this stream was placed in Category I: streams that exhibit
consistent natural reproduction and maintain a wild population of one or more
trout species without any stocking. Class HH - No Data
Presumptive Class A1 -
Indicator Bacteria: 2006-2008
Class A2 - Indicator
Bacteria: No Data
Presumptive Class A1 and Class A2 – pH: 2021-2022
Class BCW1 - Binomial Parameters: 2021-2022
Class BCW1 – Trout Natural Reproduction:
Assessment Key Dates
| 1/3/2006 | Monitoring Start |
| 9/4/2008 | Monitoring End |
| 1/1/2024 | Biological Monitoring |
| 1/1/2012 | TMDL Completed |
| 5/27/2021 | Monitoring Start |
| 9/13/2022 | Monitoring End |
Methods
| 120 | Surveys of fish and game biologists/other professionals |
| 150 | Monitoring data more than 5 years old |
| 200 | Physical/Chemical Monitoring |
| 330 | Fish surveys |
| 420 | Indicator bacteria monitoring |