North Raccoon River IA 04-RAC-1140
from confluence with Drainage Ditch 101 (S36 T91N R36W Buena Vista Co.) to confluence with unnamed tributary in S4 T92N R36W Buena Vista Co.
- Cycle
- 2018
- Release Status
- Final
- Overall IR
- 3 - Insufficient data exist to determine whether any designated uses are met.
- Trend
- Unknown
- Created
- 7/8/2019 1:47:18 PM
- Updated
- 8/5/2019 12:04:18 PM
The presumptive Class A1 (primary contact recreation) uses remain "not assessed" due to the lack of information upon which to base an assessment. The Class B(WW2) aquatic life uses remain assessed as "partially supported" based on a 2013 fish kill and on the results of biological monitoring and habitat assessment conducted as part on an October 1994 DNR stream use assessment.
The fish kill occurred on or before August 30, 2013 with no known cause, source or responsible party identified. Approximately 558 dead fish were found in 0.50 miles of affected stream. According to DNR’s assessment/listing methodology, the occurrence of a single pollutant-caused fish kill, or a fish kill of unknown origin, on a waterbody or waterbody reach during the most recent assessment period indicates a severe stress to the aquatic community and suggests that the aquatic life uses should be assessed as “impaired”. If a cause of the kill was not identified during the DNR investigation, or if the kill was attributed to non-pollutant causes (e.g., winterkill), the assessment type will be considered “evaluated.” Such assessments, although suitable for Section 305(b) reporting, lack the degree of confidence to support addition to the state Section 303(d) list of impaired waters (IR Category 5). Waterbodies affected by such fish kills will be placed in IR subcategories 2b or 3b and will be added to the state list of waters in need of further investigation. Because no cause or source was identified for this 2013 fish kill, the Class B(WW2) aquatic life uses are placed in Category 3b for the current IR cycle. The Class B(WW2) aquatic life uses remain assessed (evaluated) as "partially supported" based on results of biological monitoring and habitat assessment conducted as part on an October 1994 DNR stream use assessment. A review of the field sheet from the October 1994 DNR stream use assessment showed a fish community of 4 species. Most of the expected species/genera of Class B(LR) streams in the Des Moines Lobe sub-ecoregion were not present during this assessment (only 3 of the 11 expected fish taxa for Des Moines Lobe streams were present). Although the data upon which this assessment were originally based have aged well beyond 10 years (now 20+ years)--and are thus considered far too old to characterize current water quality conditions--the indication of a potential impairment suggests that this stream segment should remain assessed (evaluated) as "partially supported" and thus remain in IR Category 3b (i.e., on Iowa's list of waters in need of further investigation). Follow-up monitoring is needed to update this assessment, to determine the status of the aquatic communities of this stream, and to determine the degree to which the aquatic life uses may be impaired.