Iowa DNR

Water Quality Assessments

Impaired Waters List

West Nishnabotna River IA 05-NSH-1441

from confluence with Silver Cr. (S21, T71N, R41W, Mills Co.) to confluence Farm Cr. in S9, T73N, R40W, Mills Co.

Assessment Cycle
Release Status
Result Period
1990 - 1992
Assessment Type
Integrated Report
Category 0
Legacy ADBCode
IA 05-NSH-0080_1
Overall Use Support
Aquatic Life Use Support
Fish Consumption
Not assessed
Assessment Comments

Assessment is based on results of IDNR ambient monthly water quality monitoring near Malvern.

Basis for Assessment

No violations of Class B(WW) WQC; thus should assess as FST due to known threats from agricultural NPS.   Rivers in this portion of the state, however, are impaired due to several factors:  (1) removal of riparian trees with the resultant destabilization of stream banks and habitat degradation; (2) high rates of erosion from agricultural land contribute large amounts of sediment to stream channels with resultant siltation of substrates and habitat degradation; (3) channelization that results in widening of channel and further degradation of habitat.

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