Assessment Comments
Assessment is based on results of (1) 1995 DNR stream use assessment, (2) a 1994 DNR/UHL biocriteria sampling (Fish IBI= 57(good), BM-IBI= 64(good)), and (3) occurrence of fish kills. See attached document for details.
Basis for Assessment
SUMMARY: The Class B(WW) aquatic life uses were assessed as "partially supported." Fish consumption uses remain "not assessed." EXPLANATION: The previous assessment of the Class B(WW) uses was based on results from (1) a DNR/UHL bioassessment in 1994 and a DNR stream use assessment survey in 1995 (see assessment developed for the 1998 report above). An updated interpretation of the results of the DNR/UHL biocriteria sampling of fish and benthic macroinvertebrates in 1994 continues to suggest that the aquatic life uses are "fully supported / threatened." That is, based on a comparison to results of ecoregion reference site sampling, the fish community was rated "good" (Fish IBI=57) and the benthic macroinvertebrate community was also rated "good" (MB IBI=64). These results suggest that the Class B(WW) uses are "fully supported / threatened." The current assessment of aquatic life uses, however, is based primarily on the occurrence of a fish kill during the most recent three-year period. As noted in the assessment developed for the 1998 report (above), a fish kill occurred on this reach of Crane Creek in September 1997. According to DNR's Section 305(b) assessment methodology, the occurrence of this pollution-caused fish kill within the last three years suggests that the aquatic life uses should be assessed as "partially supported." An additional, more recent kill occurred on August 28, 1998, on a tributary of this segment of Crane Creek. This kill was attriubted to animal waste from a beef cattle feedlot; an estimated 11,534 fish were killed. This kill was apparently confined to the unnamed tributary and did not affect Crane Creek. Thus, although results of biological monitoring in 1994 and 1995 suggest only threats to the full support of the aquatic life uses, the recent occurrence of a fish kill in Crane Creek suggests an impairment of the Class B(WW) aquatic life uses. The fish consumption uses remain "not assessed" due to the lack of recent fish contaminant monitoring in this stream reach.
