Centerville Reservoir Lower IA 05-CHA-1319

Appanoose County S12T68NR18W near Centerville.

Open Data Collection Period Modal

For purposes of developing stream/river water quality assessments for integrated reporting, three years of water quality data are typically used for both conventional pollutant parameters (e.g., indicator bacteria) and the less frequently monitored toxic parameters (e.g., toxic metals). Since the 2004 IR cycle, DNR has used a three-year data gathering period for streams, rivers, and beaches. For most assessments, the use of three years of data increases the number of samples upon which the decision on use support is based and helps address the problem of weather-related year-to-year fluctuations in water quality.

Due to the lower sampling frequency in Iowa’s ambient lake, biological, fish kill, and fish tissue monitoring programs, five years of data are used for developing IR assessments and for identifying Section 303(d) listings.

Data Type	Data Timeframe
Beach Sampling Data	CY 2012 - 2014
Stream/River Water Quality Data	CY 2012 - 2014
Lake Water Quality Data	CY 2010 - 2014
Biological Sampling Data	CY 2010 - 2014*
Fish Kill Data	CY 2010 - 2014
Fish Tissue Sampling Data	CY 2010 - 2014
Continuous Dissolved Oxygen Sampling Data	CY 2010 - 2014
*Biological sites sampled in both 2009 and 2013 were also assessed.

Open Segment Map
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Cycle: 2016
Release Status: Final
Overall IR: 2 - Some of the designated uses are met but there is insufficient data to determine if remaining designated uses are met.
Trophic: Unknown
Trend: Stable
Created: 5/19/2016 9:35:53 AM
Updated: 5/19/2016 9:35:53 AM

Use Support

Class A1

Recreation - Primary contact

Not Assessed

Class BLW

Aquatic Life - Lakes and wetlands

Not Assessed

Class C

Drinking Water -

Fully Supported

Class HH

Human Health -

Not Assessed

General Use

General Use water -

Not Assessed

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The Class A1 (primary contact recreation), Class B(LW) (aquatic life) uses and fish consumption uses remain "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" due to continued decrease in average levels of atrazine. 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. NOTE: Centerville Reservoir was not monitored through the Syngenta Voluntary Atrazine Monitoring Program from 2007 through 2010.

Assessment Explanation

The Class A1 and Class B(LW) uses remain not assessed due to the lack of water quality information needed to assess these uses.   This lake is not monitored as part of Iowa's ambient statewide lake monitoring network.

The Class C (drinking water) uses remain assessed (monitored) as “fully supported” based on results of the Syngenta “Iowa Voluntary Atrazine Monitoring Program” from 2004 through 2006.   NOTE: Centerville Reservoir was not monitored through the Syngenta Voluntary Atrazine Monitoring Program from 2007 through 2010.   The monitoring from 2004 through 2006 showed that the time-weighted mean levels of atrazine in the samples were well below the MCL of 3.0 ug/L.   The mean and median atrazine concentrations over this three-year period (N= 82) were 1.0 ug/L and 0.9 ug/L, respectively.   The maximum value for this period was 2.5 ug/L.   None of the 49 moving annual averages for atrazine for 2004, 2005, or 2006 at Centerville Reservoir exceeded the MCL of 3.0 ug/L.   Based on IDNR’s assessment methodology, if the average contaminant level in source water is less than the MCL, the Class C uses of the source water should be assessed as “fully supported.”

The Class C (drinking water) uses were assessed as “not supported” for the 2004 assessment/listing cycle based on results of sampling conducted as part of the Iowa Voluntary Atrazine Monitoring Program in 2000, 2001, and 2002 by Syngenta Crop Protection, Inc.   Results of this program from 2000 through 2002 showed thirty-two of the 48 moving annual averages calculated for the 2000-02 period were above the MCL of 3 ug/l (range:  3.5 to 4.9 ug/l).   Based on DNR's Section 305(b) assessment methodology, the Class C (drinking water) uses of Lower Centerville Reservoir were assessed as "not supported" for the 2004 reporting cycle.   Data used for the 2006 assessment/listing cycle suggested that levels of atrazine were below the MCL and suggested “full support” of the Class C uses.   Centerville Reservoir, however, remained on the 303d list to ensure that atrazine levels were consistently below the MCL.   Results from 2004-2006 again suggest that annual average levels of atrazine have not exceeded the MCL.   Therefore, based on continued low levels of atrazine at Centerville Reservoir, the Class C uses are assessed as “fully supported” and the lake is proposed for removal from the state’s 303d list.

Fish consumption uses remain not assessed due to a lack of fish tissue data at this lake.

Monitoring and Methods

Assessment Key Dates

1/13/2004

Fixed Monitoring Start Date

5/15/2006

Fixed Monitoring End Date

Methods

270

PWS chemical monitoring (ambient water)