Big Creek Lake IA 04-UDM-1242

Assessment Comments

Basis for Assessment

SUMMARY:  Assessed support of the Class A (primary contact recreation) uses as "fully supported."  The Class B(LW) aquatic life uses remained assessed as "fully supporting / threatened."  Fish consumption uses remain assessed as "fully supporting." EXPLANATION:  Levels of indicator bacteria at Big Creek beach were monitored approximately twice per week during summer 1999 by DNR Parks, Recreation and Preserves Division as part of a beach monitoring program at 11 state-owned lakes.   Results of the 34 samples collected at Big Creek beach showed that levels of indicator bacteria (fecal coliforms) were generally low, with the overall geometric mean (38 orgs/100 ml) well below the state WQ criterion of 200 orgs/100 ml.   The maximum level of fecal coliforms in the 34 samples was 770 orgs/100 ml on June 7, 1999; this was the only sample that exceeded the EPA-recommended single sample maximum density for fecal coliform bacteria of 400 orgs/100ml.   None of the sixteen 30-day periods had geometric means (N from 6 to 10) greater than the state WQ standard of 200 orgs/100ml.; the maximum 30-day geometric mean was 38 orgs/100ml.   Thus, the Class A (primary contact recreation) uses were assessed as "fully supported."  The Class B(LW) aquatic life uses remain assessed as fully supporting / threatened based on review and approval of the previous (1998) assessment (see above) by the DNR Fisheries Bureau in 2000.   Fish consumption uses remained assessed as "fully supported" based on results of EPA/DNR fish tissue (RAFT) monitoring in 1994 that showed levels of all contaminants were less than ½ of the respective FDA action levels and DNR levels of concern in the composite sample of fillets from channel catfish (see assessment for the 1996 report above).