Fairfield Reservoir 1 IA 03-SKU-909

Alternate name(s) for this segment: Bonnifield Lake | Fairfield Municipal Reservoir 1

Jefferson County S13&24T72NR10W near Fairfield

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.

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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: Unknown
Created: 5/23/2016 2:59:44 PM
Updated: 5/23/2016 2:59:44 PM

Use Support

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 B(LW) (aquatic life) uses and the 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 (evaluated) as "fully supported" based on the results of the Iowa Voluntary Atrazine Monitoring Program conducted in 2000 and 2001 by Syngenta Crop Protection, Inc.

Assessment Explanation

The Class B(LW) uses remain not assessed due to a lack of information on the aquatic communities of this lake.

The assessment of support of the Class C (drinking water) uses remains based on the results of the Syngenta "Iowa Voluntary Atrazine Monitoring Program" in 2000 and 2001. Because these data are now too old (greater than five years) the assessment is considered evaluated (lower confidence), not monitored (of higher confidence). Results of this monitoring showed that the time-weighted mean levels of atrazine in samples collected from this reservoir in these two calendar years were below the MCL of 3.0 ug/l. The time-weighted mean of atrazine in 2000 (N=30) was 1.6 ug/l and in 2001 (N=31) was 1.2 ug/l. Only one of the combined 60 samples collected from this reservoir in 2000 and 2001 exceeded the MCL of 3.0 ug/l with a value of 3.6 ug/l. Based on DNR's Section 305(b) assessment methodology, if the average contaminant levels in source water are less than the MCL, the Class C (drinking water) uses of the source water should be assessed as "fully supported." This waterbody remains in IR Category 2a.

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

Monitoring and Methods

Assessment Key Dates

1/10/2000

Fixed Monitoring Start Date

12/10/2001

Fixed Monitoring End Date

Methods

270

PWS chemical monitoring (ambient water)