Assessment Comments

Assessment is based on results of (1) IDNR/UHL ambient monthly water quality monitoring near Missouri Valley from 2002-04 and (2) USGS ambient monitoring in 2004.

Basis for Assessment

SUMMARY:  The Class B(WW) aquatic life uses are assessed (monitored) as "fully supported" based on results of chemical/physical water quality monitoring conducted from 2002 through 2004.   Fish consumption uses remain "not assessed" due to the lack of fish contaminant monitoring in this river segment.   This assessment is based on results of (1) IDNR/UHL monthly ambient monitoring conducted during the 2002-2004 assessment period at the County Road F-58 bridge NE of Missouri Valley (STORET station 10430001 (formerly station 822304)) and (2) USGS chemical/physical water quality monitoring at Logan from March 2004 through September 2004.  

EXPLANATION:  Monitoring at the IDNR station near Missouri Valley showed no violations of Class B(WW) water quality criteria for dissolved oxygen, pH, or ammonia in the 36 samples analyzed during the 2002-2004 period.   The maximum value of ammonia-nitrogen was 0.8 mg/l.   In addition, levels of pesticides in the seven samples analyzed, and levels of toxic metals in the ten samples analyzed, were all below the respective Class B(WW) criteria.   Similarly, no violations of state water quality criteria occurred in the approximately ten samples collected from the USGS station at Logan that were analyzed for dissolved oxygen, pH, ammonia, chlorpyrifos, DDE, and dieldrin.   The results from both the IDNR and USGS monitoring stations suggest "full support" of the Class B(WW) aquatic life uses.  

Fish consumption uses remain "not assessed" due to the lack of fish contaminant monitoring in this river segment.