Lindsey Creek IA 01-MAQ-54

mouth (S3 T89N R5W Delaware Co.) to north line S16 T90N R5W Delaware Co. (prior to 1990 designated for Class B(w) uses.)

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.

Open Segment Map
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Cycle: 2018
Release Status: Final
Overall IR: 5 - Water is impaired or threatened and a TMDL is needed.
Trend: Unknown
Created: 7/18/2019 8:48:49 AM
Updated: 7/18/2019 8:49:48 AM

Use Support

Class A1

Presumptive Use

Recreation - Primary contact

Not Supported

Bacteria: Indicator Bacteria- E. coli

Support Level

Not Supported

Impairment Code

5p - Impairment occurs on a waterbody with a presumptive A1 or B(WW1) use.

Cause Magnitude

High

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

Low

Cycle Added

2014

Impairment Rationale

Geometric mean criterion exceeded

Data Source

Watershed project monitoring

TMDL Priority

Tier III

Class BWW1

Presumptive Use

Aquatic Life - Warm Water Type 1

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 (monitored) as “partially supported” due to levels of indicator bacteria that exceed state water quality criteria. The presumptive Class B(WW1) aquatic life uses remain "not assessed" due to the lack of information upon which to base an assessment. The source of data used for this assessment is the results of bacterial monitoring conducted from April to July 2014 on Lindsey Creek at 165th Avenue in Delaware County.

Assessment Explanation

The Class A1 (primary contact recreation) uses are assessed (monitored) as "not supported" due to violations of Iowa’s water quality criteria for indicator bacteria. The geometric mean of E. coli in the eight samples collected at the monitoring station on Lindsey Creek from April to July 2014 was 2,274 orgs/100 ml. All eight samples (100%) exceeded Iowa’s single-sample maximum criterion of 235 orgs/100 ml. According to U.S. EPA guidelines for Section 305(b) reporting and DNR’s assessment/listing methodology, if the geometric mean of E. coli is greater than the state criterion of 126 orgs/100 ml., the primary contact recreation uses should be assessed as impaired (see pgs 3-33 to 3-35 of U.S. EPA 1997b). Thus, the Class A1 uses of this segment are assessed as “not supported”.

Monitoring and Methods

Assessment Key Dates

4/1/2014

Fixed Monitoring Start Date

7/15/2014

Fixed Monitoring End Date

Methods

420

Indicator bacteria monitoring