Little Turkey River IA 01-TRK-162

from the Clayton/Delaware county line to south line of S11 T90N R3W in Delaware 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 2016 - 2018
Stream/River Water Quality Data	CY 2016 - 2018
Lake Water Quality Data	CY 2014 - 2018
Biological Sampling Data	CY 2014 - 2018*
Fish Kill Data	CY 2014 - 2018
Fish Tissue Sampling Data	CY 2014 - 2018
Continuous Dissolved Oxygen Sampling Data	CY 2014 - 2018
*Biological sites sampled in both 2013 and 2017 were also assessed.

Open Segment Map
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Cycle: 2020
Release Status: Final
Overall IR: 5 - Water is impaired or threatened and a TMDL is needed.
Trend: Unknown
Created: 8/14/2020 3:05:36 PM
Updated: 10/15/2020 7:22:24 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

N/A

Cycle Added

2012

Impairment Rationale

Geometric mean criterion exceeded

Data Source

TMDL monitoring: Iowa DNR

TMDL Priority

Tier III

Class A2

Presumptive Use

Recreation - Secondary 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

N/A

Cycle Added

2012

Impairment Rationale

Geometric mean criterion exceeded

Data Source

TMDL monitoring: Iowa DNR

TMDL Priority

Tier III

Class BCW1

Aquatic Life - Cold Water Type 1

Partially Supported

Biological: low aquatic macroinvertebrate IBI

Support Level

Partially Supported

Impairment Code

5b-t - Biological - tentative

Cause Magnitude

Slight

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

Low

Cycle Added

2008

Impairment Rationale

Low Biotic Index

Data Source

Special project/study

TMDL Priority

Tier IV

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 and Class A2 uses remain assessed as "not supported” due to high levels of indicator bacteria (E. coli) that exceeded state water quality criteria. The Class BCW1 use remains assessed as "partially supported" based on biological sampling data. All other designated uses were "not assessed".

Assessment Explanation

Sources of Data:

Data Source	Data Source ID	Data Type	Data Age	Site ID	Site Name	Site Description
Iowa DNR	6	WQ	CY 2010	11280002	Little Turkey River	Near Colesburg (Site LTR1)
Iowa DNR	6	BIO	See Below	631	Little Turkey River	Colesburg (DS)

Presumptive Class A1 - Indicator Bacteria:

Site ID	Data Source ID	# Samples / # Years	2010 Geometric Mean	Annual Geometric Mean Violation	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
11280002	6	16 / 1	2523	Yes	14	88%	Yes	Evaluated	Not

Presumptive Class A2 - Indicator Bacteria:

Site ID	Data Source ID	# Samples / # Years	2010 Geometric Mean	Annual Geometric Mean Violation	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
11280002	6	16 / 1	2523	Yes	9	56%	Yes	Evaluated	Not

Class BCW1 - Biological Sampling:

Benthic Macroinvertebrates:

BioNet Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage/Thermal	BM Sample Gear	CBI score	CBI Class	CBI BIT	CBI Pass/ Fail
631	7/18/12	7	52b	MS/CW	Hess	34	NA	60	Fail

Overall Assessment:

Community	Assessment Type	Assessment Result	Support Level	Earned IR Category	Actual IR Category	Reason
Benthic Macroinvertebrates	Evaluated	Fail (0/1)	Partial	3bc	5bt	Assessment is evaluated because it was based on an old single sample.

Class BCW1 - Trout Natural Reproduction:

In contrast to the benthic macroinvertebrate data, based on the January 2020 trout reproduction in Iowa streams summary prepared by the DNR Fisheries Bureau, the Class BCW1 coldwater aquatic life use of the Little Turkey River was assessed as "fully supported". According to the updated summary, this stream was placed in Category II: streams that exhibit recent but inconsistent reproductive success and occasional stocking may be needed to maintain the trout population(s).

Class HH - No Data

Monitoring and Methods

Assessment Key Dates

3/10/2010

Fixed Monitoring Start Date

7/26/2010

Fixed Monitoring End Date

1/1/2020

Biological Monitoring

7/18/2012

Biological Monitoring

Methods

120

Surveys of fish and game biologists/other professionals

150

Monitoring data more than 5 years old

315

Regional reference site approach

320

Benthic macroinvertebrate surveys

330

Fish surveys

420

Indicator bacteria monitoring