Iowa DNR
Iowa DNR
ADBNet
Water Quality Assessments
Impaired Waters List

Mill Creek IA 06-LSR-1615

mouth (S14 T92N R40W Cherokee Co.) to confluence with Whisky Cr. at east line S29 T94N R41W O'Brien 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 3:11:50 PM
Updated
12/1/2025 9:51:31 AM
Use Support
Class A1
Recreation - Primary contact
Not Assessed
Class BWW2
Aquatic Life - Warm Water Type 2
Not Supported
Support Level
Not Supported
Impairment Code
5b-v - Biological - verified
Cause Magnitude
Slight
Status
Continuing
Source
Unknown: Source Unknown
Source Confidence
Low
Cycle Added
2004
Impairment Rationale
Low Biotic Index
Data Source
Biological monitoring: Iowa DNR WQMA
TMDL Priority
Tier IV
Impairment Delistings
No delistings for this assessment cycle.
Documentation
Assessment Summary

The Class BWW2 use was assessed as “not supported” based on biological sampling data. All other designated uses were "not assessed."

Assessment Explanation

Data Sources:

Data Source

Data Source ID

Data Type

Data Age

Site ID

Site Name

Site Description

Iowa DNR

6

BIO & WQ

See Below

142

Mill Creek

NE of Meriden (REMAP#436)

Iowa DNR

6

BIO

See Below

1203

Mill Creek

Larrabee


Presumptive Class A1 - No Data

Class BWW2 - Biological Sampling:

Benthic Macroinvertebrates:

BioNet Site ID

Date

Drainage Area (mi2)

Ecoregion

Major Drainage/ Thermal

BM Sample Gear

BMIBI score

BMIBI Class

47a BMIBI BIT

BMIBI Pass/Fail

142

9/4/24

259.0

47a

MO/WW

Surber

48

Fair

54

Fail

142

9/14/23

259.0

47a

MO/WW

Surber

43

Fair

54

Fail

142

7/27/21

259.0

47a

MO/WW

Surber

44

Fair

54

Fail


Fish:

BioNet Site ID

Date

Drainage Area (mi2)

Ecoregion

Major Drainage/ Thermal

Riffle Stream?

FIBI score

FIBI Class

47a FIBI BIT

FIBI Pass/Fail

142

7/27/21

259.0

47a

MO/WW

NA

38

Fair

43

Fail

1203

9/17/19

267.0

47a

MO/WW

NA

28

Fair

43

Fail


Overall:

Community

Assessment Type

Assessment Result

Support Level

IR Category

Reason

Benthic Macroinvertebrates

Monitored

Fail (0/3)

Not

Fish

Monitored

Fail (0/2)

Not

Assessment was monitored because the samples used to complete

Overall

Monitored

Fail

Not

5bv

the assessment were collected in a recent five-year period.


Class BWW2- Continuous DO Monitoring:

Site ID

Data Source ID

# Days Monitoring (2016)

DO Criteria Type

# 2016 violations/Violations needed for impairment

Violates Annual Significantly >10% Rule?

Assessment Type

Support Level

24 hr

0/15

No

142

6

98

16 hr

0/15

No

Evaluated

Full

Monitoring and Methods
Assessment Key Dates
9/4/2024
Biological Monitoring
9/17/2019
Biological Monitoring
9/14/2023
Biological Monitoring
7/5/2016
Monitoring Start
10/10/2016
Monitoring End
7/27/2021
Biological Monitoring
Methods
150
Monitoring data more than 5 years old
200
Physical/Chemical Monitoring
315
Regional reference site approach
320
Benthic macroinvertebrate surveys
330
Fish surveys