Little Turkey River IA 01-TRK-160

mouth (S10 T91N R2W Clayton Co.) to confluence with White Pine Hollow in S31 T91N R2W Clayton Co.

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: 5 - Water is impaired or threatened and a TMDL is needed.
Trend: Unknown
Created: 4/8/2016 10:24:31 AM
Updated: 9/29/2016 7:47:37 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

Slight

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2014

Impairment Rationale

Geometric mean criterion exceeded

Data Source

Watershed project monitoring

TMDL Priority

Tier III

Class BWW1

Aquatic Life - Warm Water Type 1

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 presumptive Class A1 (primary contact recreation) uses are assessed (monitored) as “partially supported” (IR 5p) due to levels of indicator bacteria that slightly exceed state water quality criteria. The Class B(WW1) aquatic life uses are assessed (monitored) as “fully supported” (IR 2a) based on results of water quality monitoring from April 2012 to October 2014. Fish consumption uses remain not assessed (IR 3a) due to lack of data upon which to base an assessment. The data used for this assessment are from STORET station 15220015 (LIT10) at Highway 52 approximately six miles south of Guttenberg in Clayton County.

Assessment Explanation

The presumptive Class A1 (primary contact recreation) uses are assessed (monitored) as "partially supported" based on levels of indicator bacteria that slightly exceeded state water quality criteria. The geometric means of indicator bacteria (E. coli) in the 23 samples collected during the recreational seasons of 2012 through 2014 at monitoring station 15220015 were as follows: the 2012 geometric mean was 415 orgs/100 ml, the 2013 geometric mean was 586 orgs/100 ml, and the 2014 geometric mean of eight samples was 147 orgs/100 ml. All three geometric means exceed the Class A1 criterion of 126 orgs/100 ml. Eleven of the 23 samples (48%) exceeded the Class A1 single-sample maximum criterion of 235 orgs/100 ml. According to U.S. EPA guidelines for Section 305(b) reporting and IDNR’s assessment/listing methodology, if a recreation season geometric mean exceeds the respective water quality criterion, the contact recreation uses should be assessed as "impaired" (see pgs 3-33 to 3-35 of U.S. EPA 1997b). Thus, because at least one recreation season geometric mean exceeded criteria for Class A1 uses, these uses are assessed as “impaired.”

Results of chemical/physical water quality monitoring from 2014 through 2014 do not suggest impairment of the Class B(WW1) aquatic life uses. Monitoring at station 15220015 (LIT10) showed no violations of Class B(WW1) water quality criteria for ammonia (13 samples), dissolved oxygen (23 samples), pH (22 samples), temperature (23 samples), or chloride (13 samples). Thus, the Class B(WW1) aquatic life uses are assessed (monitored) as “fully supported”.

The Class HH (fish consumption) uses remain “not assessed” due to the lack of information upon which to base an assessment.

Monitoring and Methods

Assessment Key Dates

4/4/2012

Fixed Monitoring Start Date

10/1/2014

Fixed Monitoring End Date

Methods

220

Non-fixed station physical/chemical monitoring (conventional pollutant only)

420

Indicator bacteria monitoring