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
1994 - 1996
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

Upgraded the assessment of support of the Class B(WW) aquatic life uses from PS to FST due to (1) lack of violations of Class B(WW) WQ criteria in the 8 samples collected from November 1989 and September 1991 (thus suggesting full support of use) and (2) lack of additional information (e.g., biological information) for determining whether the Class B(WW) uses are impaired.   Additional monitoring is needed to determine the status of the aquatic communities and habitats of this river and to determine the degree to which the Class B(WW) uses might be impaired.   The WQ data from the DNR quarterly monitoring station are more than 5 years old; thus, the assessment category was downgraded to "evaluated."  Another two-year cycle of quarterly WQ monitoring at this station began in October 1998.

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