Middle River IA 04-LDM-1086
from confluence with Clanton Cr. (S28T76N R25W Warren Co.) to confluence with Bush Branch in S8 T75N R29W Madison Co.
- Cycle
- 2016
- Release Status
- Final
- Overall IR
- 2 - Some of the designated uses are met but there is insufficient data to determine if remaining designated uses are met.
- Trend
- Unknown
- Created
- 9/20/2016 10:17:56 AM
- Updated
- 10/18/2016 4:35:24 PM
The Class A1 (primary contact recreation) uses remain "not assessed" (IR 3a) due to the lack of information upon which to base an assessment. The Class B(WW1) aquatic life uses are assessed (evaluated) as "fully supported” (2a) based on results of biological sampling in 1998, 2004 and 2012. Fish consumption uses are assessed (evaluated) as "fully supported" (IR 2a) based on results of fish contaminant monitoring in 2002 and 2014. Sources of data for this assessment include (1) results of IDNR/SHL biological sampling conducted in 1998, 2004 and 2012 as part of the stream biocriteria project, (2) a report of a fish kill on July 20, 2002, and (3) results of U.S. EPA/IDNR fish contaminant (RAFT) monitoring in 2014.
The Class B(WW1) aquatic life uses are assessed (evaluated) as "fully supported” based on results of IDNR/SHL biological sampling conducted on this stream segment in 1998, 2004 and 2012. The 1998 FIBI score was 38 (fair) and the BMIBI score was 61 (good). The 2004 FIBI score was 32 (fair) and the BMIBI score was 53 (fair). The 2012 FIBI score was 40 (fair) and the BMIBI score was 63 (good). The aquatic life use support was assessed as fully supporting (=FS), based on a comparison of the FIBI and BMIBI scores with biological impairment criteria (BIC) established for previous Section 305(b) reports. The biological impairment criteria were determined from a statistical analysis of data collected at stream ecoregion reference sites from 1994-2008. The FIBI BIC for this ecoregion is 36 and the BMIBI BIC for this ecoregion is 51. This segment passed the FIBI BIC 2/3 times and passed the BMIBI BIC 3/3 times in the last 17 years. This aquatic life assessment is now considered "evaluated" based on a change in the 2010 IDNR assessment methodology. IDNR now requires a segment have two or more biological samples collected from the segment in multiple years over a recent five-year period to be considered “monitored”. This segment had multiple samples collected in the previous 17 years (1998-2014); however, the multiple samples were not collected during a five-year period. A fish kill occurred in this river segment on July 20, 2002 near the Middle River Park south of Winterset. This kill is believed due to warm water temperatures, low river flow, and the die-off of an algae bloom that reduced levels of dissolved oxygen below that needed to sustain large fish. At the time of the kill, levels of dissolved oxygen were in the vicinity of 3 mg/l; the water was brownish, probably due to the senescence of the algal bloom. Because this kill is largely due to natural causes (low flow; high water temperatures), the kill does not influence the assessment of support of the designated aquatic life uses of this stream segment. Fish consumption uses are assessed (monitored) as “fully supported” based on results of U.S.EPA/IDNR fish contaminant (RAFT) monitoring southwest of Winterset in 2014. The composite samples of fillets from channel catfish and flathead catfish had low levels of contaminants. Levels of primary contaminants in the composite sample of channel catfish fillets were as follows: mercury: 0.08 ppm; total PCBs: 0.06 ppm; and technical chlordane: <0.05 ppm. The average level of mercury in the five flathead catfish analyzed was 0.07 ppm. These levels of contaminants are far below Iowa DNR/Iowa Dept. of Public Health consumption advisory thresholds and thus suggest “full support” of fish consumption uses.