Assessment Comments

Assessment based on results of IDNR ambient monitoring.

Basis for Assessment

SUMMARY:  The Class B(LR) aquatic life uses remain assessed as "fully supported / threatened."   EXPLANATION:  The assessment of support of the Class B(LR) uses is based on results of (1) monitoring conducted on Old Mans Creek near Iowa City from March 1996 to September 1998 by USGS as part of the National Water Quality Assessment Program (NAWQA) (eastern Iowa river basins study unit, station 05455100) and (2) a DNR biocriteria sampling in August 1994.   Results of the USGS/NAWQA monitoring showed no violations of Class B(LR) water quality criteria in the 39 samples analyzed for pH, dissolved oxygen, and ammonia.   In addition, no violations of Class B(LR) chronic criteria occurred in the 24 samples analyzed for toxic organic compounds and pesticides.   Although the monitoring results for conventional and toxic parameters suggests "full support" of the aquatic life uses, the assessment of "fully supported / threatened" is used due to concerns with results of past biological monitoring.   Additional biological monitoring is needed to better determine the status of the aquatic communities of this stream.   Although results of USGS/NAWQA monitoring in September 1995 suggest that fish consumption uses are "fully supported" (see assessment for the 1998 report), Class B(LR) streams are not considered designated for fish consumption uses.