Cedar River IA 02-CED-450
from Sugar Cr. (S17 T78N R2W Muscatine Co.) to confluence with Rock Run Cr. in S28 T80N R3W Cedar 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
- 8/3/2016 2:33:24 PM
- Updated
- 9/23/2016 2:11:17 PM
The Class A1 (primary contact recreation) uses remain "not assessed" (IR 3a) due to the lack of water quality information upon which to base an assessment. The Class B(WW1) aquatic life uses remain assessed (evaluated) as "fully supported" (IR 2a) based on results of IDNR/SHL stream REMAP biological sampling in 2006. Fish consumption uses remain assessed (evaluated) as "fully supported" (IR 2a) based on results of U.S. EPA/IDNR fish contaminant (RAFT) monitoring in 2006.
The Class A1 uses remain "not assessed" due to the lack of water quality data or information upon which to base an assessment.
The Class B(WW1) aquatic uses remain assessed (evaluated) as “fully supported" based on data collected in 2006 as part of the IDNR/SHL stream REMAP project. A series of biological metrics that reflect stream water quality and habitat integrity were calculated from the biocriteria sampling data. The biological metrics are based on the numbers and types of benthic macroinvertebrate taxa and fish species collected in the stream sampling reach. The biological metrics were combined to make a fish community index of biotic integrity (FIBI) and a benthic macroinvertebrate index (BMIBI). The indexes rank the biological integrity of a stream sampling reach on a rising scale from 0 (minimum) to 100 (maximum). The 2006 FIBI score was 54 (good) and the BMIBI score was 43 (fair). The aquatic life use support was assessed (evaluated) as fully supporting (=FS), based on a comparison of the FIBI and BMIBI scores with biological impairment criteria (BIC) established 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 site passed the BMIBI BIC using the BMIBI UAV of 8 points. This assessment is considered evaluated because the drainage area (7243 mi2) above this sampling site was greater than the maximum limit (500 mi2) that was used to calibrate the Iowa wadeable stream impairment criteria. Even though this site passed both the FIBI and BMIBI BICs, it is uncertain as to whether or not this segment is meeting the aquatic life criteria because the site used for the assessment doesn’t fall in the calibrated watershed size.
Fish consumption uses remain assessed (evaluated) as “fully supported” based on results of U.S.EPA/IDNR fish contaminant (RAFT) monitoring near West Branch in 2006. The results from the 2006 sampling show low levels of the primary contaminants (chlordane, PCBs and mercury) in the composite sample of common carp fillets: mercury: 0.266 ppm; total PCBs: 0.09 ppm; and technical chlordane: <0.03 ppm. The existence of, or potential for, a fish consumption advisory is the basis for Section 305(b) assessments of support of fish consumption uses in Iowa’s rivers and lakes.
Note: Both the biological and fish tissue data from 2006 are now approaching 10 years old; thus, the data are not considered reliable enough to consider the assessment as "monitored" and likely too old to represent current water quality conditions.