Assessment Comments
Assessment remains based on results of U.S. EPA/IDNR fish contaminant (RAFT) monitoring in 2007.
Basis for Assessment
SUMMARY: The Class B(LW) aquatic life uses remain "not assessed" due to a lack of information at this lake. The fish consumption uses remain assessed (monitored) as "fully supported/threatened" based on results of fish contaminant (RAFT) monitoring in 2007.
EXPLANATION: Fish consumption uses remain assessed (monitored) as “fully supported/threatened” based on results of U.S.EPA/IDNR fish contaminant (RAFT) monitoring at Central City Ponds in 2007. The composite samples of fillets from yellow bullhead and largemouth bass had generally low levels of contaminants. Levels of primary contaminants in the composite sample of yellow bullhead fillets were as follows: mercury: 0.0526 ppm; total PCBs: 0.231 ppm; and technical chlordane: <0.13 ppm. Levels of primary contaminants in the composite sample of largemouth bass fillets were as follows: mercury: 0.0788 ppm. The level of total PCBs in the sample of yellow bullhead, however, exceeds the IDNR/IDPH trigger level of 0.2 ppm for a one meal per week consumption advisory. The existence of, or potential for, a fish consumption advisory is the basis for Section 305(b) assessments of the degree to which Iowa’s lakes and rivers support their fish consumption uses. According to the IDNR/IDPH advisory protocol, two consecutive samplings that show contaminant levels are above the trigger level in fillet samples are needed to justify issuance of an advisory. Thus, additional monitoring will be conducted at Central City Ponds to determine whether an advisory is needed for this waterbody. According to IDNR’s assessment methodology, the occurrence of contaminant above an advisory trigger level suggests that “full support” of the fish consumption uses is “threatened.”
