Assessment Comments
Assessment is based on 2002 DNR/UHL REMAP data: Fish IBI= 36 (fair), BM-IBI= 43 (fair) and on 1998 DNR/UHL biocriteria data: Fish IBI=43 (fair), BM-IBI=75 (good).
Basis for Assessment
SUMMARY: For the 2004 reporting period, the assessment of Class B(LR) aquatic life uses was downgraded to "partially supporting" (PS) from "fully supported / threatened" (FS/T) for the 2002 reporting period. The assessment segment includes data collected in 1998 and 2002 as part of the DNR/UHL stream biocriteria and REMAP projects. The 1998 Fish IBI score was 43 (fair) and the BM-IBI score was 75 (good). The 2002 Fish IBI score was 36 (fair) and the BM-IBI score was 43 (fair). Relying on the more recent (2002) data, the aquatic life use support was assessed as partially supporting (=PS). The assessment was based on a comparison of the F-IBI and BM-IBI scores 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.
EXPLANATION: The 2004 assessment relies on more recent (2002) sample data collected from a different (upstream) area of the assessment segment. This area exhibited degraded physical habitat and water quality conditions compared with stream reference site conditions. Elevated levels of total phosphorus, TSS, and turbidity were found in two summer base flow water samples. Seston (water column) chlorophyll a, and high estimated rates of gross primary production and community respiration were indicative of a nutrient/organically-enriched environment. Several types of physical habitat alteration were evident, including removal (grazing) of riparian vegetation, bank destabilization, channel widening, and excessive sediment deposition.
