Little Sioux River IA 06-LSR-1577

Assessment Comments

Assessment is based on results of IDNR ambient monthly city monitoring upstream of Spencer in 2000 & 2001.

Basis for Assessment

[Note:  For the 2002 report, the previous waterbody segment for the Little Sioux River (IA 06-LSR-0040-1), which extended 44 miles from the confluence with the Ocheyedan River at Spencer (Clay Co.) to confluence with the West Fork Little Sioux River in Dickinson Co., was split into two subsegments:  (1) Ocheyedan River at Spencer to confluence with Milford Creek (Dickinson Co.) (IA 06-LSR-0040-1) and (2) Milford Creek to confluence with West Fork Little Sioux River (Dickinson Co.) (IA 06-LSR-0040-2).   See previous assessments from this subsegment for historic Section 305(b) assessments for the original 44-mile river reach.]

SUMMARY:  The Class B(WW) aquatic life uses are assessed as "fully supported."  Fish consumption uses remain "not assessed."  The source of data for this assessment is the results of monthly monitoring from October 1999 through September 2001 at the IDNR ambient city monitoring station located upstream from Spencer at the Highway 18 bridge northwest of Spencer (station 10210002).   EXPLANATION:  The biological data upon which the 2000 assessment was based were collected in 1996 (see assessment for the 2000 report above).   These data are now considered too old (greater than five years) for characterizing current water quality conditions.    For the 2002 reporting cycle, the Class B(WW) aquatic life uses are assessed as "fully supported."  Monitoring at the IDNR city station showed no violations of Class B(WW) water quality criteria for dissolved oxygen, pH, or ammonia-nitrogen in the 14 samples collected, for toxic metals in the 14 samples analyzed, or for pesticides in the six samples analyzed, during the 2000-2001 biennial period.   These results suggest full support of the Class B(WW) aquatic life uses.   Fish consumption uses remain "not assessed" due to the lack of recent fish contaminant monitoring data for this river segment.