Beaver Creek IA 02-CED-555

Assessment Comments

Assessment is based on results of: (1) IDNR/UHL ambient monthly monitoring NW of Cedar Falls from 2000-02 and (2) 2001 Fisheries data: Fish IBI = 61 (good).

Basis for Assessment

SUMMARY:  The Class B(WW) aquatic life uses are assessed (monitored) as “fully supported” based on results of ambient water quality monitoring and IDNR Fisheries data.   Fish consumption uses remained "not assessed" due to the lack of fish contaminant monitoring in this stream segment.   The source of data for this assessment is the results of IDNR monthly ambient monitoring from January 2000 through December 2002 at the county road T75 bridge approximately 3.5 miles northwest of Cedar Falls (STORET station 10070001) and 2001 IDNR Fisheries sampling results.

EXPLANATION:  Results of IDNR ambient water quality monitoring station NW of Cedar Falls during the 2000-2002 assessment period showed no violations of Class B(WW) water quality criteria.   That is, no violations of state water quality criteria for conventional parameters (dissolved oxygen, pH, and ammonia-nitrogen) occurred in the 39 samples collected during this monitoring period; levels of pesticides were below levels of detection in the nine samples analyzed during the assessment period.   Fish consumption uses remain "not assessed" due to the lack of fish contaminant monitoring in this stream reach.

The assessment was partially based on data collected in 2001 as part of a DNR Fisheries stream sampling project: Manchester research station.   A series of biological metrics which reflect stream water quality and habitat integrity were calculated from the Fisheries sampling data.   The biological metrics are based on the numbers and types of fish species that were collected in the stream sampling reach.   The biological metrics were combined to make a fish community index of biotic integrity (F-IBI).   The index ranks the biological integrity of a stream sampling reach on a rising scale from 0 (minimum) to 100 (maximum).   The 2001 evaluated Fish IBI = 61 (good).   The aquatic life use support was assessed (evaluated) as Fully Supporting (=FS), based on a comparison of the F-IBI score with biological assessment criteria established for previous Section 305(b) reports.   The biological assessment criteria were determined from a statistical analysis of data collected at stream ecoregion reference sites from 1994-2001.