Iowa DNR
Iowa DNR
ADBNet
Water Quality Assessments
Impaired Waters List

Brush Creek IA 01-VOL-317

mouth (S26 T93N R7W Fayette Co.) to confluence with Bear Cr. in S8 T92N R7W Fayette 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 3:09:29 PM
Updated
12/2/2025 9:28:20 AM
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
Moderate
Cycle Added
2016
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 slightly 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

15330002

Brush Creek at Bush Road/C24

BRU10

Iowa DNR

6

BIO

See Below

165

Brush Creek

Wadena


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

15330002

6

24 / 3

113

211

38

Yes

4

17%

No

Evaluated

Not


Class BWW2 - Biological Sampling:

Benthic Macroinvertebrates:

Site ID

Date

Drainage Area (mi2)

Ecoregion

Major Drainage

BM Sample Gear

BMIBI score

BMIBI Class

52b BMIBI BIT

BMIBI Pass/Fail

165

7/30/24

31.7

52b

MS

Hess

81

Excellent

61

Pass

165

9/2/20

31.7

52b

MS

Hess

75

Good

61

Pass


Fish:

Site ID

Date

Drainage Area (mi2)

Ecoregion

Major Drainage

Riffle Stream?

FIBI score

FIBI Class

52b FIBI BIT

FIBI Pass/Fail

165

7/30/24

31.7

52b

MS

NA

90

Excellent

52

Pass

165

9/3/20

31.7

52b

MS

NA

78

Excellent

52

Pass


Overall:

Community

Assessment Type

Assessment Result

Support Level

IR Category

Reason

Benthic Macroinvertebrates

Monitored

Pass (2/2)

Full

Fish

Monitored

Pass (2/2)

Full

Assessment was monitored because the assessment was

Overall

Monitored

Pass

Full

1

based on samples collected in a recent five-year period.

Monitoring and Methods
Assessment Key Dates
4/4/2012
Monitoring Start
11/5/2014
Monitoring End
9/2/2020
Biological Monitoring
9/3/2020
Biological Monitoring
7/30/2024
Biological Monitoring
Methods
150
Monitoring data more than 5 years old
315
Regional reference site approach
320
Benthic macroinvertebrate surveys
330
Fish surveys
420
Indicator bacteria monitoring