Assessment Comments
Assessment is based on results of a fish kill investigation in August 2007 and results of U.S. EPA/IDNR fish contaminant (RAFT) monitoring in 2009.
Basis for Assessment
SUMMARY: The Class B(LW) aquatic life uses of this waterbody are assessed (evaluated) as “partially supported” due to a fish kill in August 2007. The kill was attributed to natural causes. This impairment is appropriate for Category 2b of Iowa’s 2014 Integrated Report. The fish consumption uses are assessed as "fully supported" based on fish tissue monitoring in 2009.
EXPLANATION: The fish kill occurred on or before August 16, 2007. The kill was attributed to unknown causes, however human causes were suspected. The kill claimed 922 fish, including 710 crappie, 198 bluegill, seven bullheads and seven green sunfish; no estimate of the value of these fish was made.
The DNR plans to continue to investigate the source, which may be a substance from Harlan’s storm sewer. A storm sewer outfall from the City of Harlan sends storm water into Little Lake George without treatment. While high water temperatures can stress fish during summer months, samples collected at the lake by DNR staff showed high levels of dissolved oxygen, indicating the fish kill was likely caused by a pollutant.
This is the same assessment as that developed for the 2010 and 2012 assessment/listing cycles. The continuance of the IR Category 3b listing is based on IDNR's 2014 assessment methodology that states the following: the occurrence of a single pollutant-caused fish kill, or a fish kill of unknown origin, on a waterbody or waterbody reach during the most recent assessment period (2008-2011) indicates a severe stress to the aquatic community and suggests that the aquatic life uses should be assessed as “impaired”. If a cause of the kill was not identified during the IDNR investigation, or if the kill was attributed to non-pollutant causes (e.g., winterkill), the assessment type will be considered “evaluated” and will be placed in IR subcategories 2b or 3b and will be added to the state list of waters in need of further investigation. Thus, this assessment segment will remain in Category 2b of Iowa’s 2014 Integrated Report.
Fish consumption uses were assessed (monitored) as “fully supported” based on results of U.S. EPA/IDNR fish contaminant (RAFT) monitoring at Little George Pond in 2009. The composite samples of fillets from channel catfish and largemouth bass had low levels of contaminants. Levels of primary contaminants in the composite sample of channel catfish fillets were as follows: mercury: 0.0078 ppm; total PCBs: 0.09 ppm; and technical chlordane: <0.03 ppm. Levels of primary contaminants in the composite sample of largemouth bass fillets were as follows: mercury: 0.0839 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 fish contaminant data generated from the 2009 RAFT sampling conducted at this lake show that 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.
