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 2014 - 2016
Stream/River Water Quality Data	CY 2014 - 2016
Lake Water Quality Data	CY 2012 - 2016
Biological Sampling Data	CY 2012 - 2016*
Fish Kill Data	CY 2012 - 2016
Fish Tissue Sampling Data	CY 2012 - 2016
Continuous Dissolved Oxygen Sampling Data	CY 2012 - 2016
*Biological sites sampled in both 2011 and 2015 were also assessed.

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Cycle: 2018
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: 10/16/2018 2:25:06 PM
Updated: 8/27/2019 2:31:23 PM

Use Support

Class A1

Recreation - Primary contact

Fully Supported

Class BLW

Aquatic Life - Lakes and wetlands

Not Assessed

Class C

Drinking Water -

Not Assessed

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 presumptive Class A1(primary contact recreation) uses are assessed as "fully supporting". 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 The sources of data for this assessment include results of (1) IDNR/UHL beach monitoring from 2014 through 2016 and (2) Voluntary Atrazine Monitoring Program conducted in 2000 and 2001 by Syngenta Crop Protection, Inc.

Assessment Explanation

NOTE: Presumptive Class A1(primary contact recreation) was added to this segment this cycle due to the presence of a monitored swimming beach on this lake.

Results of DNR beach monitoring from 2014 through 2016 suggest that the Class A1 uses are "Fully Supported." Levels of indicator bacteria at Fairfield Waterworks Park Beach were monitored once per week during the primary contact recreation seasons (May through September) of 2014 (13 samples), 2015 (14 samples) and 2016 (14 samples), as part of the DNR beach monitoring program. According to DNR’s assessment methodology two conditions need to be met for results of beach monitoring to indicate “full support” of the Class A1 (primary contact recreation) uses: (1) the geometric mean of the samples from each recreation season of the three-year assessment period are less than the state's geometric mean criterion of 126 E. coli orgs/100 ml and (2) not more than 10% of the samples during any one recreation season exceeds the state's single-sample maximum value of 235 E. coli orgs/100 ml. If a sampling season geometric mean exceeds the state criterion of 1000 orgs/100 ml during the three-year assessment period, the Class A1 uses should be assessed as “not supported.” Also, if a sampling season geometric mean exceeds the state criterion of 126 orgs/100 ml during the three-year assessment period and/or if significantly more than 10% of the samples in any one of the three recreation seasons exceed Iowa's single-sample maximum value of 235 E. coli orgs/100 ml, the Class A1 uses should be assessed as “partially supported.” This assessment approach is based on U.S. EPA guidelines (see pgs 3-33 to 3-35 of U.S. EPA 1997b).

At Fairfield Waterworks Park Beach, the geometric means from 2014, 2015 and 2016 were all below the Iowa water quality standard of 126 E. coli orgs/100 ml. The geometric mean was 19 E. coli orgs/100 ml in 2014, 22 E. coli orgs/100 ml in 2015 and 14 E. coli orgs/100 ml in 2016. The percentage of samples exceeding Iowa's single-sample maximum criterion (235 E. coli orgs/100 ml) was 8% in 2014, 7% in 2015 and 0% in 2016. None of these are significantly greater than 10% of the samples and therefore do not suggest impairment of the Class A1 uses. According to DNR's assessment methodology and U.S. EPA guidelines, these results suggest "Fully Supported" of the Class A1 uses, however, this lake is not designated for Class A1 use and will be assessed as "not assessed" for Class B(LW) (aquatic life) uses.

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

The Class C (drinking water) uses are considered "not assessed" due to the lack of information upon which to base an assessment. The previous assessments of the Class C uses at this lake ["fully supported"] were based on results of sampling conducted by Syngenta "Iowa Voluntary Atrazine Monitoring Program" in 2000 and 2001. However, because these data are now considered too old (greater than ten years) to accurately characterize current water quality conditions, these uses are now considered "not assessed."

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

Monitoring and Methods

Assessment Key Dates

6/2/2014

Fixed Monitoring Start Date

8/22/2016

Fixed Monitoring End Date

Methods

270

PWS chemical monitoring (ambient water)