Iowa DNR

Water Quality Assessments

Impaired Waters List

Iowa River IA 02-IOW-641

from confluence Timber Cr. (S3 T83N R17W Marshall Co.) to confluence with Asher Cr. in S27 T84N R18W Marshall Co.

Assessment Cycle
Result Period
1996 - 1998
Assessment Type
Integrated Report
Category 0
Legacy ADBCode
IA 02-IOW-0060_4
Overall Use Support
Aquatic Life Use Support
Fish Consumption
Not assessed
Primary Contact Recreation
Assessment Comments

Assessment is based on results of IDNR ambient monthly monitoring downstream from Marshalltown.

Basis for Assessment

SUMMARY:  The Class A (primary contact recreation) uses remain assessed as "partially supported," and the Class B(WW) aquatic life uses remain assessed as "fully supported / threatened."  Fish consumption uses remain "not assessed."  EXPLANATION:  Due to the absence of recent water quality information, continued to use the assessments of support of the Class A and Class B(WW) uses developed for the 1998 report (see above).   These assessments were based on results of water quality monitoring during the 1996-1997 biennial period from the DNR quarterly monitoring station at Marshalltown.   Results from stations monitored monthly or more frequently, however, are preferred for Section 305(b) assessments in order to improve the accuracy and confidence level of the assessment.   As part of DNR's expanded water quality monitoring program, monthly monitoring at the Marshalltown station began in October 1999.   The fish consumption uses remained "not assessed" due to a lack of recent fish tissue monitoring in this river reach.

Monitoring and Methods
Assessment Key Dates
420 Water column surveys (e.g. fecal coliform)
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