Home Lake IA 05-GRA-1373

Assessment Comments

Assessment is based on: results of the Iowa Voluntary Atrazine Monitoring Program conducted from 2004 through 2006 by Syngenta Crop Protection, Inc.

Basis for Assessment

SUMMARY:  The Class B(LW) (aquatic life) uses are “not assessed” due to the lack of water quality information upon which to base an assessment.   The Class C (drinking water) uses are assessed (monitored) as “fully supported.”  Fish consumption uses remain "not assessed" due to the lack of fish contaminant monitoring in this lake.    The source of data for this assessment is the results of the Iowa Voluntary Atrazine Monitoring Program conducted from 2004 through 2006 by Syngenta Crop Protection, Inc.    

EXPLANATION:  The Class B(LW) (aquatic life) uses remain “not assessed” due to the lack of water quality information for this lake.    

The Class C (drinking water) uses are assessed (monitored) as "fully supported" based on results of sampling conducted as part of the Iowa Voluntary Atrazine Monitoring Program in 2004, 2005, and 2006 by Syngenta Crop Protection, Inc.    Results of monitoring in 2000, 2001, and 2002 suggested that the Class C drinking water uses were “not supported” due to levels of atrazine that exceeded the MCL.   Results of more recent (2003-2006), monitoring, however, suggest a decline in atrazine levels at this lake.   This monitoring showed that the time-weighted mean levels of atrazine in the samples collected in 2004, 2005, and 2006 were all below the MCL of 3.0 ug/L.   The mean and median atrazine level over this three year period (N=97) was 1.8 ug/L.   The maximum single sample atrazine value for this period was 4.8 ug/L, which was the only single sample value that exceeded the MCL.   None of the 65 moving annual averages in 2004, 2005, or 2006 exceeded the MCL (maximum = 2.1 ug/L).   Based on IDNR’s assessment methodology and a continued decrease in atrazine levels at Home Pond the Class C uses are assessed as “fully supported” for the 2008 assessment/listing cycle.  

Fish consumption uses remain "not assessed" due to the lack of fish contaminant monitoring at this lake.