Assessment Comments

Assessment is based on results of IDNR monthly ambient monitoring 4 mi N of Indianola during 2000 & 2001.

Basis for Assessment

SUMMARY:  The Class B(WW) aquatic life remain assessed (evaluated) as "fully supported / threatened."  Fish consumption uses remain "not assessed."  The primary source of data for this assessment is the results of IDNR ambient monthly monitoring during the 2000-2001 biennial period at station 10910001 (formerly station 200551) at the USGS gaging station approximately 1.5 miles west of Highway 65-69 near Indianola.   EXPLANATION:  The Class B(WW) aquatic life uses are assessed as "fully supported / threatened."  None of the 24 samples collected during the 2000-2001 biennial period at the IDNR monthly station violated Class B(WW) water quality criteria for pH or ammonia-nitrogen; no violations occurred in the four samples analyzed for toxic metals or in the 6 samples analyzed for pesticides and other toxic organic compounds.   However, one of the 24 samples violated the Class B(WW) criterion for dissolved oxygen:  the sample collected on December 13, 2000 contained 4.8 mg/l of dissolved oxygen.   According to U.S.  EPA guidelines for Section 305(b) water quality assessments (U.S.  EPA 1997b, page 3-17), the percentage of violations for dissolved oxygen at this station (4.2%) does not suggest a water quality impairment (the EPA guidelines allow up to 10% violations of these conventional parameters before impairment of water quality is indicated).   Although results of chemical monitoring suggest relatively good water quality and full support of the aquatic life uses of this river segment, previous assessments has indicated potential impacts due to alteration of aquatic habitats (see assessments for previous 305(b) reports above).   Thus, the Class B(WW) aquatic life uses remain assessed as "fully supported /threatened."  Fish consumption uses remain "not assessed" due to the lack of recent fish contaminant monitoring in this stream segment.