West Nishnabotna River IA 05-NSH-1441

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.