Assessment Comments

Assessment is based on results of IDNR ambient monthly monitoring SW of Waterloo, fish tissue (RAFT) monitoring near Hudson in 1998. See attached document for details.

Basis for Assessment

SUMMARY:  The Class A (primary contact recreation) uses were considered "not assessed."  The Class B(WW) aquatic life uses remained assessed as "fully supported / threatened."  The fish consumption uses were assessed as "fully supported."  EXPLANATION:  The DNR quarterly water quality monitoring station on Black Hawk Creek near Waterloo, upon which previous (1994 and 1996) assessments of support of the Class A and Class B(WW) uses were based, has not been monitored since the 1994-95 biennial period.   These data are now considered too old (greater than five years) for developing a valid assessment of support of the Class B(WW) uses.   As part of DNR's expanded water quality monitoring program, monthly monitoring at the Waterloo station began in October 1999.   Results from this monitoring will allow development of an updated assessment of support of beneficial uses for the 2002 report.   The Class B(WW) uses remain assessed as "fully supported / threatened" based on results of DNR biocriteria sampling in this stream reach in July 1996 (see assessment for the 1998 report above).   Fish consumption uses were assessed as "fully supported" based on results of EPA/DNR fish tissue (RAFT) monitoring in 1998 near Hudson that showed levels of contaminants in composite samples of fillets from channel catfish were less than ½ the respective FDA action levels and DNR levels of concern.   Levels of the primary contaminants of concern in the 1998 sample were as follows (all values are wet weight):  technical chlordane:  0.055 mg/kg; dieldrin:  0.096 mg/kg; PCB-Aroclor 1260:  0.016 mg/kg (Aroclors 1248 and 1254 were not found above detection levels); and mercury:  0.102 mg/kg.