Iowa DNR
Iowa DNR
ADBNet
Water Quality Assessments
Impaired Waters List

Turkey River IA 01-TRK-156

from confluence with N. Br. Turkey R. (S31 T99N R11W Howard Co.) to confluence with S. Br. Turkey R. in S2 T98N R12W Howard Co.

This is a DRAFT assessment
Draft assessments may change without notice
Cycle
2026
Current Phase
Public Comment
Overall IR
5 - Water is impaired or threatened and a TMDL is needed.
Trend
Stable
Created
10/27/2025 3:09:35 PM
Updated
12/3/2025 2:04:09 PM
Use Support
Class A1
Recreation - Primary contact
Not Supported
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 BWW2
Aquatic Life - Warm Water Type 2
Fully Supported
Impairment Delistings
No delistings for this assessment cycle.
Documentation
Assessment Summary

The presumptive Class A1 use remains assessed as “not supported” due to levels of indicator bacteria (E. coli) that exceeded state water quality criteria. The Class BWW2 use was assessed as "fully supported" based on biological sampling data.

Assessment Explanation

Data Sources:

Data Source

Data Source ID

Data Type

Data Age

Site ID

Site Name

Site Description

Iowa DNR

6

WQ

CY 2012-2014

15450015

Turkey River @ V46

TR90

Iowa DNR

6

BIO

See Below

1022

Turkey River

US confluence with North Fork Turkey – TK008


Presumptive Class A1 - Indicator Bacteria:

Site ID

Data Source ID

# Samples / # Years

2012 Geometric Mean

2013 Geometric Mean

2014 Geometric Mean

Annual Geometric Mean Violation

# Violations

% Violations

Significantly >10% Violations

Assessment Type

Support Level

15450015

6

23 / 3

284

606

163

Yes

14

61%

Yes

Evaluated

Not


Class BWW2 - Biological Sampling:

Fish:

Site ID

Date

Drainage Area (mi2)

Ecoregion

Major Drainage

Riffle Stream?

FIBI score

FIBI Class

47c FIBI BIT

FIBI Pass/Fail

1022

8/21/19

28

47c

MS

Undetermined

65

Good

44

Pass

1022

7/31/18

28

47c

MS

Undetermined

63

Good

44

Pass

1022

8/7/17

28

47c

MS

Undetermined

64

Good

44

Pass

1022

8/16/16

28

47c

MS

Undetermined

71

Excellent

44

Pass


Overall:

Community

Assessment Type

Assessment Result

Support Level

IR Category

Reason

Fish

Evaluated

Pass (4/4)

Full

Overall

Evaluated

Pass

Full

1

Assessment was evaluated because the assessment used sample(s) collected more than five years ago.


Monitoring and Methods
Assessment Key Dates
4/4/2012
Monitoring Start
11/5/2014
Monitoring End
8/21/2019
Biological Monitoring
8/16/2016
Biological Monitoring
8/7/2017
Biological Monitoring
7/31/2018
Biological Monitoring
Methods
150
Monitoring data more than 5 years old
315
Regional reference site approach
330
Fish surveys
420
Indicator bacteria monitoring