West Lake Corning IA 05-NOD-1394

Assessment Comments

Assessment remains based on (1) results of sampling and analysis of this lake’s fish populations conducted by the IDNR Fisheries Bureau in 2003, and (2) results of U.S. EPA/IDNR fish tissue (RAFT) monitoring at West Corning Reservoir in 2007.

Basis for Assessment

SUMMARY:  The Class B(LW) aquatic life uses remain assessed (evaluated) as “fully supported” based on results of sampling and analysis of this lake’s fish populations in 2003.   The Class C (drinking water) uses remain “not assessed” due to the lack of recent information upon which to base an assessment.   This lake is not designated for contact recreation uses in Iowa's Surface Water Classification (http://www.iowadnr.gov/water/standards/files/swcdoc2.pdf).   The fish consumption uses remain assessed (monitored) as "fully supported" based on fish tissue monitoring in 2007.   The sources of data for this assessment include (1) results of lake fish surveys by the IDNR Fisheries Bureau in 2003 and (2) results of U.S.  EPA/IDNR fish contaminant (RAFT) monitoring in 2007.   This lake is not part of the IDNR/ISU, 2000-2007 statewide survey of Iowa lakes nor has this lake been monitored as part of the IDNR/UHL 2005-2008 ambient monitoring program.  

Note:  A TMDL for siltation at West Lake Corning was prepared by IDNR and approved by EPA in 2001; thus, this lake was placed into IR Category 4a (TMDL approved) for the 2004 assessment/listing cycle.   Based on subsequent monitoring, the fish populations were shown as not being impacted by siltation.   Thus, this waterbody was moved from IR Category 4a to Category 2a (not impaired) for the 2006 assessment/listing cycle.   West Lake Corning remained in IR Category 2a for the 2008 assessment/listing cycle and remains in IR Category 2a for the current (2014) cycle.    

EXPLANATION:  The Class B(LW) aquatic life uses of West Corning Lake remain assessed (monitored) as “fully supported.”  Staff from the IDNR Fisheries Bureau sampled the fish population of this lake September 8, 10, and 17, 2003.   Night electro-fishing was used on September 8 with daytime electrofishing, fyke nets on the 10th, and trap nets on the 17th, respectively.   Based on the analysis of the fish populations at this lake performed by IDNR Fisheries Biologists, (i.e., length/frequency analysis, growth rates (relative weight analysis), and population estimates), the fish population of West Corning Lake appears to meet expectations, thus suggesting an “full support” of the Class B(LW) aquatic life use.   Comments from IDNR Biologists, based on their 2003 sampling and analysis, suggest that the sport fishery of this lake is in quite good condition with large numbers of healthy bluegill, largemouth bass, and crappie.   Population estimates show abundant numbers of largemouth bass, bluegill and other fish species.   No undesirable fish were found.   A similar sample in 2002 showed similar catches and no undesirable fish species.   IDNR Fisheries staff note that the presence of yellow bass and common carp in nearby lakes (for example, Binder Lake) keeps the West Corning Lake fishery at risk.   It is unlikely that either species currently exists in West Corning Lake, but their introduction to the lake is still possible.   This possibility, combined with the risk of future species contamination from water pumped between the West Corning, Binder, and Icaria lake systems, makes future sampling imperative and renovation of West Corning Lake’s fish population probable.    

The Class C (drinking water) uses remain “not assessed” due to the lack of recent monitoring data upon which to base an assessment.   In previous 305(b) assessment cycles, the Class C uses were assessed  as "fully supported/threatened” (not impaired) based on results of sampling conducted by UHL in January 1995.   These data, however, are now far greater than 10 years in age and are thus considered too old to accurately characterize current water quality conditions.  

Fish consumption uses remain assessed (monitored) as “fully supported” based on results of U.S.   EPA/IDNR fish contaminant (RAFT) monitoring at West Corning Reservoir in 2007.   The composite samples of fillets from channel catfish and an unknown fish had low levels of contaminants.   Levels of primary contaminants in the composite sample of channel catfish fillets were as follows: mercury: 0.0181 ppm; total PCBs: 0.09 ppm; and technical chlordane: <0.03 ppm.   Levels of primary contaminants in the composite sample of the unknown fish fillets were as follows: mercury: 0.0426 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 2007 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.