Red Rock Reservoir IA 04-LDM-1017

Sources of Data:

Class A1 - Indicator Bacteria:

Class A1 - pH:

Class A1 - Lake TSI's

Class BWW1 - Conventional Parameters:

Class BWW1 - Lake Planktonic Cyanobacteria:

Class BWW1 - Fish Kill:

The Class BWW-1 uses are assessed (evaluated) as “partially supported” due to fish kills that occurred in Noverber of 2016.Because the cause of the fish kill was not identified, or the fish kill was attributed to a non-pollutant cause (e.g., winterkill), the assessment type is “evaluated.” Segments assessed using “evaluated” assessments are placed in Category 3b and are added to the state list of waters in need of further investigation. If no additional fish kills are reported in the segment for a 10 year period, the Category will be changed from 3b to 3a (water not assessed).

Details about the 2009 fish kill can be found here:https://programs.iowadnr.gov/fishkill/Events/915

Class HH - Fish Tissue Sampling:

Fish consumption uses were assessed (monitored) as “fully supported” based on results of ACOE/ISU fish contaminant monitoring at Red Rock Lake in 2012, 2013, and 2014. The composite samples of whole-fish common carp had low levels of contaminants. Levels of total chlordane in the composite samples were as follows: 2012: 0.003 ppm; 2013: 0.003 ppm; 2014: 0.130 ppm. None of these levels approach the advisory trigger level of 0.6 ppm for chlordane. In 2012, 2013, and 2014, composite samples of whole-fish carp were analyzed for total PCBs and Aroclors 1248, 1254, and 1260. Total PCBs in composite samples of whole-fish carp were 0.002 ppm (2012) and 0.002 (2013). PCB Aroclors 1248, 1254, and 1260 were all 0.0002 ppm (2014). In addition, the 2009 and 2010 composite samples of whole-fish carp were analyzed for PCBs (Aroclors), and composite samples of fillets from a predator species (largemouth bass (Micropterus salmoides)) were analyzed for mercury. Levels of PCBs in composite whole-fish carp samples for all Aroclors analyzed (1016, 1221, 1232, 1242, 1248, 1254, and 1260) were all below levels of detection (range from 0.02 to 0.09 ppm). The average level of mercury in the composite sample of largemouth bass fillets in 2009 was 0.1 ppm and in 2010 was 0.12 ppm. The levels of PCBs and mercury seen in fish tissue samples from ISU/ACOE station 8 in Red Rock Reservoir are well below the one meal per week advisory trigger of 0.20 ppm for total PCBs (sum of Aroclors 1248, 1254, and 1260) and for mercury (0.30 ppm).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. The levels of contaminants do not exceed any of the advisory trigger levels, thus indicating no justification for issuance of a consumption advisory for this waterbody.