Assessment Comments
Basis for Assessment
SUMMARY: The Class B(LW) aquatic life uses and the fish consumption uses remain "not assessed." The Class C (drinking water) uses were assessed as "fully supported / threatened." EXPLANATION: The Class B(LW) uses were not assessed due to a lack of information on the aquatic communities of this lake. The Class C (drinking water) uses were assessed as "fully supported / threatened" based on the 1998 results of the Novartis "Iowa Voluntary Atrazine Monitoring Program." This monitoring showed that the time-weighted mean level of atrazine in samples collected from January to December 1998 (1.6 ug/l, N=31, maximum=4.3 ug/l) was below the MCL of 3.0 ug/l. Based on DNR's Section 305(b) assessment methodology, if the average contaminant level in source water is less than the MCL, but a level in one or more samples is above the MCL, the Class C (drinking water) uses of the source water should be assessed as "fully supported / threatened." Thus, the Class C uses of Fairfield Municipal Reservoir 1 were assessed as "fully supported / threatened." Fish consumption uses were "not assessed" due to the lack of fish contaminant monitoring at this lake.
