Volga River IA 01-VOL-294

Assessment Comments

Assessment is based on results of (1) IDNR/UHL TMDL monitoring in 2000 and (2) biological monitoring in 2000 conducted by the IDNR Fisheries Bureau [Fish IBI = 79 (excellent)].

Basis for Assessment

EXPLANATION:  The Class B(WW) aquatic life uses were assessed (evaluated) as "fully supported" based on (1) the lack of violations of state water quality criteria for pH and dissolved oxygen in the nine samples collected in 2000 from the TMDL monitoring station on the Volga River near at White Pine Forrest Preserve upstream from Volga (Site 36) and (2) results of IDNR/Fisheries Bureau biological monitoring in 2000.   The samples from the TMDL station were not analyzed for either ammonia, toxic metals, or other toxic organic compounds.   The fish consumption uses remain "not assessed" due to the lack of recent fish tissue monitoring in this river reach.   This is the same assessment as that developed for the 2004 assessment/listing cycle.

The assessment of the Class B(WW) uses 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 = 79 (excellent).   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.