Assessment Comments

Assessment is based on results of IDNR ambient monthly monitoring near Pisgah (950032 - 21IOWA/DNR) in 2000 & 2001.

Basis for Assessment

[Note:  For the 2002 report, the previous waterbody segment for the Soldier River (IA 06-SOL-0010-0), which extended 35 miles from its mouth to confluence with East Soldier River near Ute in Monona Co., was split into two subsegments:  (1) mouth to confluence with an Jordan Creek near Moorhead (Monona Co.) (IA 06-SOL-0010-1, this one) and (2) Jordan Creek to East Soldier River near Ute, Monona Co.  (IA 06-SOL-0010-2).   See historical assessments from this subsegment for previous Section 305(b) assessments for the original 35-mile river reach.]

SUMMARY:  The Class B(WW) aquatic life uses are assessed as "fully supported / threatened."  Fish consumption uses remain "not assessed."  This assessment is based on results of IDNR monthly ambient monitoring conducted during the 2000-2001 biennial period at the County Road F20 bridge west of Pisgah (station 10430002 (formerly station 950032)).   EXPLANATION:  Monitoring at the IDNR station near Pisgah showed no violations of Class B(WW) water quality criteria during the 2000-2001 biennial period for dissolved oxygen (minimum value = 6.1 mg/l), pH (range = 7.7 to 8.9 units), or ammonia-nitrogen (maximum value = 2.0 mg/l) in the 24 samples analyzed.   In addition, levels of toxic metals in the four samples analyzed were all below the analytical level of detection.   One of the four samples analyzed for pesticides, however, contained chlorpyrifos above the Class B(WW) chronic criterion:  the sample collected on May 2, 2001 contained 0.05 ug/l and thus exceeded the Class B(WW) chronic criterion of 0.041 ug/l.   According to U.S.  EPA guidelines for Section 305(b) reporting (U.S.  EPA 1997b, page 3-18), results for toxic parameters for least 10 samples collected over a three-year perios are needed to develop a "monitored" assessment.   Further, these guidelines allow up to one violation of aquatic life criteria in these 10 samples before "impairment" is suggested.   Because only four samples were collected at the Pisgah during the 2000-2001 biennial period, too few data are available for a "monitored" assessment.   Thus, the aquatic life uses are assessed ("evaluated") as "fully supported / threatened" based, in part, on the single violation of the Class B(WW) chronic criterion for chlorpyrifos.   Fish consumption uses remain "not assessed" due to the lack of recent fish contaminant monitoring in this river segment.