Iowa DNR

Water Quality Assessments

Impaired Waters List

Cedar River IA 02-CED-449

mouth (S20, T75N, R4W, Louisa Co.) to confluence with Sugar Cr. in S17, T78N, R2W, Muscatine Co.

Assessment Cycle
Release Status
Result Period
1994 - 1996
Assessment Type
Integrated Report
Category 0
Legacy ADBCode
IA 02-CED-0010_0
Overall Use Support
Aquatic Life Use Support
Fish Consumption
Primary Contact Recreation
Assessment Comments

Assessment is based on results of (1) DNR monthly ambient station NE of Conesville and (2) USGS NAWQA monitoring of water quality and fish tissue near Conesville.

Basis for Assessment

Used results from the DNR quarterly WQ monitoring station near Conesville to develop assessments of support of designated uses.   The Class B(WW) aquatic life uses were assessed as FS due to lack of violations of Class B(WW) WQ criteria for either conventional or toxic contaminants in the 8 samples collected during the monitoring period.   Class A primary contact uses were assessed as FS due to the relatively low levels of fecal coliform bacteria:  in the three non-flow affected samples, the geometric mean was 78 orgs/100 ml and no samples (0%) exceeded 400 orgs/100 ml (see page 3-34 of the supplement to the EPA guidelines for preparation of the 1998 Section 305(b) reports).   Overall support assessed as FST due to known threats from nonpoint source pollutants.   Used results from fish tissue monitoring conducted for the USGS National Water Quality Assessment (NAWQA) program in the eastern Iowa river basins study area.   The whole-fish composite sample of carp collected in September 1995 at Conesville contained some of the highest levels of the organochlorine compounds detected at the 16 sites in this study.   Levels of all contaminants, however, were below respective FDA action levels, although the level of dieldrin (approximately 0.2 mg/kg) exceeded 1/2 its FDA action level of 0.3 mg/kg.   Thus, assess support of fish consumption uses as fully supported/threatened (FST).  For more information on the USGS study, see USGS Fact Sheet FS-027-97 (March 1997).   Additional monitoring is needed to determine the status of the aquatic communities in this reach of the Cedar River.

Monitoring and Methods
Assessment Key Dates
230 Fixed station physical/chemical (conventional plus toxic pollutants)
Monitoring Levels
Biological 0
Habitat 0
Physical Chemistry 3
Toxic 0
Pathogen Indicators 0
Other Health Indicators 0
Other Aquatic Life Indicators 0
# of Bio Sites 0
BioIntegrity N/A
Causes and Sources of Impairment
Causes Use Support Cause Magnitude Sources Source Magnitude