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
- 2020
- Release Status
- Final
- Data Collection Period
- Overall IR Category
- 5 - Water is impaired or threatened and a TMDL is needed.
- Trend
- Unknown
- Created
- 10/5/2020 2:00:14 PM
- Updated
- 10/16/2020 7:13:03 AM
Assessment Summary
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 presumptive Class A2 use remains assessed as “fully supported” based on the same indicator bacteria monitoring data. The Class BCW1 use remains assessed as "not supported" due to violations of the water quality criterion for dissolved oxygen. 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). Because not all impairments identified for this assessment segment are covered by the TMDL (impairment of aquatic life use due to low dissolved oxygen), this segment remains in Category 5a of Iowa's Integrated Report (impaired and TMDL required).
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 2006-2008 15030008 Norfolk Creek at Co. Rd. W48 Presumptive
Class A1 - Indicator Bacteria: Historical 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 Presumptive
Class A2 - Indicator Bacteria: Historical 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 47 / 3 148 151 214 No 3 6% No Evaluated Full Class
BCW1 - Conventional Parameters: Historical 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 15030008 6 Ammonia 46 / 3 0.05 0.05 0.05 0 / 0 0% / 0% No Evaluated Full 15030008 6 Chloride 38 / 2 16 12.9 13 NA / 0 NA / 0% No Evaluated Full 15030008 6 Dissolved oxygen 27 / 1 13.9 10.0 9.9 0 / NA 0% / NA No Evaluated Full 15030008 6 Temperature 27 / 1 20.8 13.5 15.4 3 / 0 11%/ 0% No Evaluated Full The
results of the water quality monitoring from May 2004 to November 2006 show 26
violations of the Class BCW1 criteria for dissolved oxygen (7.0 mg/l) in the 79
samples collected for a violation frequency of 33%. According to the DNR
assessment and listing methodology, the percentage of violations of the
dissolved oxygen criterion in this stream segment during the 2004-06 period was
significantly greater than 10% and thus the Class BCW1 uses of this segment
were assessed as Section 303(d) impaired for the 2010 cycle. Based on DNR's IR
methodology, two consecutive assessment/listing cycles without significantly
greater than 10% of the samples violating the standard are necessary to suggest
de-listing of an impairment due to low dissolved oxygen. Therefore, the
impairment for dissolved oxygen has remained for the subsequent
assessment/listing cycles. Class
BCW1 – Trout Natural Reproduction: In
contrast to the WQ results, based on the January 2020 trout reproduction in
Iowa streams summary prepared by the DNR Fisheries Bureau, the Class BCW1
coldwater aquatic life use of 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
Assessment Key Dates
| 1/3/2006 | Non-fixed Monitoring Start Date |
| 9/4/2008 | Non-fixed Monitoring End Date |
| 1/1/2020 | Biological Monitoring |
Methods
| 120 | Surveys of fish and game biologists/other professionals |
| 150 | Monitoring data more than 5 years old |
| 220 | Non-fixed station physical/chemical monitoring (conventional pollutant only) |
| 330 | Fish surveys |
| 420 | Indicator bacteria monitoring |