Assessment Comments

Assessment is based on results of IDNR/UHL ambient monthly water quality monitoring near Missouri Valley from 2000-02.

Basis for Assessment

[Note:  For the 2002 report, the previous waterbody segment for the Boyer River (IA 06-BOY-0020-0), which extended 46 miles from Willow Creek in Harrison County to East Boyer R.  in Crawford County, was split into two subsegments:  (1) Willow Creek to the Harrison/Crawford county line (IA 06-BOY-0020-1) and (2) Harrison/Crawford county line to East Boyer River near Denison (IA 06-BOY-0020-2).   See previous Section 305(b) assessments from this subsegment (IA 06-BOY-0020-1) for assessments of the original 46-mile stream segment.]

SUMMARY:  The Class B(WW) aquatic life uses are assessed (monitored) as "fully supported" based on results of chemical/physical water quality monitoring.   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 IDNR/UHL monthly ambient monitoring conducted during the 2000-2002 assessment period at the County Road F-58 bridge NE of Missouri Valley (STORET station 10430001 (formerly station 822304)).  

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 nitrogen (maximum value = 2.0 mg/l) in the 36 samples analyzed during the 2000-2002 period.   The maximum value of ammonia-nitrogen (2.0 mg/l) occurred in the sample collected on March 5, 2001; this level did not exceed the Class B(WW) criterion.   In addition, levels of pesticides in the nine samples analyzed were all below the analytical level of detection.   These results 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.