Shell Rock River IA 02-SHL-786

Assessment Comments

Assessment is based on results of water quality monitoring and RAFT fish tissue monitoring.

Basis for Assessment

SUMMARY:  The Class A uses remain "not assessed;' the Class B(WW) aquatic life uses remain assessed as "fully supported / threatened."  Fish consumption uses were assessed as "fully supported."  EXPLANATION:  Due to problems with data acquisition, the assessments of support of the Class A uses ("not assessed") and the Class B(WW) uses ("fully supported / threatened) developed for the 1998 report were used for the 2000 report.   Although the 1996-1997 monitoring results from the MPCA station near Gordonsville suggest "full support" of the Class B(WW) aquatic life uses, the apparent nutrient enrichment of this river reach should be considered a "threat" to full support.   Anecdotal information received by DNR/EPD over the last five years suggests that growth of phytoplankton is excessive, especially in the upper reaches of the Shell Rock River.   Fish consumption uses were assessed as "fully supported" based on results of EPA/DNR fish tissue (RAFT) monitoring south of Northwood in 1999 that showed (1) very low levels of very few contaminants in the composite sample of carp fillets (4 of 23 contaminants were above detection levels) and (2) levels of all contaminants were much less than ½ of their respective FDA action levels.