ADBNet

The Class B(LW) aquatic life uses of this lake are "not assessed" due to a lack of information upon which to base an assessment.

Fish consumption uses are assessed (monitored) as “fully supported” based recent data for fish contaminants that show declining levels of PCBs in Cedar Lake fish. 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. A fish consumption advisory has existed at this lake since 1986, first due to high levels of chlordane and later due to high levels of PCBs. Because of this advisory, Cedar Lake has been monitored as part of the RAFT program on an approximately every-other-year basis since 1986. Results of ongoing DNR fish contaminant monitoring in Iowa and at Cedar Lake have shown steady declines in these long-banned compounds in Iowa fish.

Results from the 2008 (0.034 ppm )and 2010(<0.03 ppm)monitoring showed that the level of technical chlordane in the composite sample of common carp fillets was far below the advisory trigger level. Additionally, the level of technical chlordane in channel catfish fillets in 2014 (<0.05,0.07ppm) and 2016 (0.05 ppm) was also well below the one meal per week consumption advisory trigger level of 0.6 ppm. These results do not suggest an impairment of the fish consumptionat Cedar Lake based ontechnical chlordane.

Results from the 2008 2008 (0.105 ppm) and 2010 (0.19 ppm) monitoring showed that the level of totalPCBsin the composite sample of common carp fillets was far below the advisory trigger level. Additionally, the level of total PCBs in channel catfish fillets in 2014 (<0.06 ppm) and 2016 (<0.06 ppm) was also well below the one meal per week consumption advisory trigger level of 0.6 ppm. These results do not suggest an impairment of the fish consumptionat Cedar Lake based ontotal PCBs.

Levels of mercury in Cedar Lake fish have generally been well below the "one meal per week" advisory threshold of 0.3 ppm. In the 2016 sample, the level of mercury in composite samples of largemouth bass (0.050 ppm)were well below this advisory trigger level.

In addition to fish tissue monitoring, turtle tissue samples were collected in 2009. Levels of primary contaminants in the shoulder tissue of snapping turtle were all below the advisory trigger level. Results from the 2009 turtle tissue monitoring were as follows: mercury: 0.0486 ppm; total PCBs: 0.113 ppm; and technical chlordane: <0.03 ppm. These results do not suggest an impairment of the fish consumption uses at Cedar Lake.

Note:A TMDL for chlordane at Cedar Lake was prepared by DNR and approved by EPA in 2001. Subsequently, levels of chlordane in Cedar Lake fish have fallen well-below DNR/IDPH consumption advisory threshold.