Iowa DNR

Water Quality Assessments

Impaired Waters List

East Nishnabotna River IA 05-NSH-1415

from confluence with Fisher Cr. (S27, T69N, R40W, Fremont Co.) to Page/Montgomery county line

Assessment Cycle
Release Status
Result Period
1994 - 1996
Assessment Type
Integrated Report
Category 0
Legacy ADBCode
IA 05-NSH-0020_2
Overall Use Support
Aquatic Life Use Support
Fish Consumption
Not assessed
Assessment Comments

Assessment is based on results from the DNR monthly water quality monitoring station at Hwy 59 near Shenandoah.

Basis for Assessment

Due to lack of biolgoical information, based the assessment of the Class B(WW) aquatic life uses on results of monthly water quality monitoirng at the DNR station at Shenandoah:  no violations Class B(WW) WQ criteria for either conventional or toxic pollutants occurred in the 24 samples collected during the October 1995 to September 1997 period.  Although this reach is not designated for Class C drinking water uses, results of pesticide monitoring show no levels of atrazine or alachlor in the 24 samples collected from Oct 95 through Sept.  1997 that exceed MCLs (ranges:  atrazine:  0.1-1.7 ug/l; alachlor:  0.1-0.4 ug/l).   Data for levels of toxic contaminants in fish are from the 1990 RAFT and are thus considered too old (>5 years) for making "monitored" Section 305(b) assessments.  The assessment of support of the Class B(WW) aquatic life uses was developed without the benefit of biological information.  Monitoring is needed to determine the status of the aquatic communities and habitats in this reach of river and to determine to what degree the Class B(WW) uses may be impaired.  Assessment of the Class B(WW) aquatic life uses was set at FST due to potential impacts of extensive channelization and other impact in the riparian corridor of this stream (e.g., stream bank erosion and removal of natural riparian vegetation).

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