Iowa River IA 02-IOW-621

Assessment Comments

Assessment is based on results of (1) USGS/NAWQA monitoring at Wapello from 1993-1995.

Basis for Assessment

Relied primarily on USGS WQ monitoring data from Wapello for years 1993 through 1995 (from annual reports on Water Resources Data-Iowa) to assess the B(WW) aquatic life uses as FST due to no violations of WQC during period.   Degree to which Class A uses supported difficult to determine since most flows were > mean monthly flow + 1 SD (i.e., flows materially affected by surface runoff).   In general, however, the summer season data for fecal coliform bacteria at this station are relatively low regardless of flow:  only 2 of seven values exceeded the Class A WQC, and the two non-flow affected values (68 and 100 per 100 ml) were below the WQC.   Thus, use BPJ to assess Class A uses as FST.  Results from fish tissue monitoring for the 1995 RAFT program show that all contaminants in the whole-fish sample of carp were less than 1/2 the FDA action levels; thus, assess support of fish consumption uses as FS.   Support of all uses threatened by agricultural nonpoint sources.