Mill Creek IA 02-IOW-695

Assessment Comments

Three stream use assessments in Johnson County.

Basis for Assessment

Used a review of the field sheet from the November 1990 DNR stream use assessment to continue to assess support of the Class B(LR) aquatic life uses as PS due to (1) relatively poor fish community diversity (9 species from 2 familes (8 cyprinids & gizzard shad)), (2) presence of less than a majority of the expected fish taxa (4 of 8) for streams in the Southern Iowa Rolling Loess Prairies subecoregion (47f), and (3) indications on field sheets of below average habitat quality (see above assessment prepared for the 1996 report).  The data upon which this assessment is based are more than 5 years old and contain data from fish collections made late in the sampling season (mid-November).   Follow-up monitoring is needed to update this assessment, to better determine the status of the aquatic communities and habitats, and to determine the degree to which the Class B(LR) uses may be impaired.  Effluent from the Solon WWTP was not believed to present a threat to the aquatic life of Mill Creek at the time of the assessment.   Absence of several expected taxa (e.g., bullheads, sunfish, & darters), however, may indicate that a wastewater-related WQ impact does exist.