Assessment Comments
Assessment based on 2000 Fisheries data: Fish IBI = 51 (good).
Basis for Assessment
The assessment was based on data collected in 2000 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 2000 evaluated Fish IBI was 51 (good). The aquatic life use support was assessed (evaluated) as Partially Supporting (=PS), 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.
The assessment type is considered as “evaluated” status because the size of the segment’s watershed exceeds the range of reference condition watershed sizes used to calibrate the benthic macroinvertebrate and fish bioassessment indexes. For this assessment, the drainage area for the segment (approximately 1,000 mi2) exceeds the maximum drainage area cutoff (500 mi2) that IDNR has established for use of BMIBI and FIBI data. Therefore, IDNR considers the aquatic life use impairments indicated by these data as “evaluated” assessments that are not appropriate for Section 303(d) listing (Category 5). IDNR does, however, consider these impairments as appropriate for listing under either Category 2b or 3b of the Integrated Report (waters potentially impaired and in need of further investigation).
In addition, The Fisheries Bureau sample data from this segment lack the necessary documentation or metadata to determine whether the data meet quality and completeness criteria required of “monitored” assessments. With respect to FIBI sample results, the following criteria are considered: sampling conditions; sampling gear; crew size; and length of stream sampled. One or more of these sample descriptors are not available for the Fisheries Bureau data from 1999-2002. Therefore, IDNR considers the aquatic life use impairments indicated by these data as “evaluated” assessments and thus as not appropriate for Section 303(d) listing (Category 5).
