Assessment Comments

Assessment is based on (1) results of IDNR/UHL ambient monthly water quality monitoring from 2000-02 near Ackworth and (2) best professional judgement of IDNR staff.

Basis for Assessment

SUMMARY:  The Class B(LR) aquatic life are assessed (evaluated) as "fully supported / threatened" based on historical assessments that have suggested minor impacts due to poor quality aquatic habitat in this river segment.   The sources of data for this assessment include (1) the results of IDNR ambient monthly monitoring during the 2000-2002 assessment period at STORET station 10910003 (formerly station 426046) at the Highway 92 bridge near Ackworth and (2) best professional judgment of IDNR staff.  

EXPLANATION:  The Class B(LR) aquatic life uses were assessed as "fully supported / threatened" due to modifications of the aquatic habitat of this river segment.   Results of ambient water quality monitoring, however, suggest good water quality and “full support” of these uses.   None of the 36 samples collected during the 2000-2002 assessment period at the IDNR/UHL monthly station violated Class B(LR) water quality criteria for pH, dissolved oxygen, or ammonia-nitrogen; no violations occurred in the nine samples analyzed for pesticides and other toxic organic compounds.   These results suggest full support of the Class B(LR) aquatic life uses.   Although results of chemical monitoring suggest relatively good water quality and “full support” of the aquatic life uses of this river segment, previous assessments have indicated potential impacts due to alteration of aquatic habitats (see, for example, the  assessment for the 1994 305(b) report).   Thus, the Class B(WW) aquatic life uses remain assessed (evaluated) as "fully supported /threatened."  Biological monitoring is needed to better define the status of aquatic communities in this river segment.