Iowa DNR
Iowa DNR
ADBNet
Water Quality Assessments
Impaired Waters List

North Branch Turkey River IA 01-TRK-223

mouth (S31 T99N R11W Howard Co.) to confluence with unnamed tributary (mouth located on left descending bank) in SE 1/4 S14 T99N R12W Howard Co

Cycle
2024
Release Status
Final
Overall IR
5 - Water is impaired or threatened and a TMDL is needed.
Trend
Unknown
Created
11/1/2023 8:12:45 AM
Updated
1/31/2024 1:51:32 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
Moderate
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 water quality monitoring data and 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

15450016

Turkey River, North Brach at 115 St

TRN10

Iowa DNR

6

BIO

See Below

1023

North Branch Turkey River

Below confluence with West Branch Turkey River


Presumptive Class A1 – Indicator Bacteria: 2012-2014

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

15450016

6

23 / 3

413

1062

214

Yes

16

70%

Yes

Evaluated

Not


Presumptive Class A1- pH: 2012-2014

Site ID

Data Source ID

# Samples / # Years

Maximum Value

Mean Value

Median Value

# Violations

% Violations

Significantly >10% Violations

Assessment Type

Support Level

15450016

6

24 / 3

9.3

8.2

8.1

1

4%

No

Evaluated

Full


Class BWW2 - Binomial Parameters: 2012-2014

Site ID

Data Source ID

Parameter Name

# Samples / # Years

Maximum Value

Mean Value

Median Value

# Acute / Chronic Violations

% Acute/ Chronic Violations

Significantly >10% Violations

Assessment Type

Support Level

15450016

6

Ammonia

16 / 2

0.46

0.08

0.05

0 / 0

0% / 0%

No

Evaluated

Full

15450016

6

Chloride

16 / 2

33

31

33

NA / 0

NA / 0%

No

Evaluated

Full

15450016

6

Dissolved Oxygen

24 / 3

12

8.1

8.5

3 / NA

12% / NA

No

Evaluated

Full

15450016

6

pH

24 / 3

9.3

8.2

8.1

1 / NA

4% / NA

No

Evaluated

Full

15450016

6

Temperature

24 / 3

28

14.3

14.5

NA / 0

NA / 0%

No

Evaluated

Full


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

1023

8/22/19

35

47c

MS

Undetermined

69

Excellent

44/65

Pass

1023

7/30/18

35

47c

MS

Undetermined

67

Excellent

44/65

Pass

1023

8/8/17

35

47c

MS

Undetermined

63

Excellent

44/65

Pass

1023

8/16/16

35

47c

MS

Undetermined

69

Excellent

44/65

Pass


Overall:

Community

Assessment Type

Assessment Result

Support Level

IR Category

Reason

Fish

Monitored

Pass (4/4)

Full

Assessment was monitored because the assessment used multiple

Overall

Monitored

Pass

Full

1

samples collected in a recent five year period to complete the assessment.


Monitoring and Methods
Assessment Key Dates
4/4/2012
Monitoring Start
11/5/2014
Monitoring End
8/16/2016
Biological Monitoring
8/22/2019
Biological Monitoring
8/8/2017
Biological Monitoring
7/30/2018
Biological Monitoring
Methods
150
Monitoring data more than 5 years old
200
Physical/Chemical Monitoring
315
Regional reference site approach
330
Fish surveys
420
Indicator bacteria monitoring