Iowa DNR
Iowa DNR
ADBNet
Water Quality Assessments
Impaired Waters List

Little Waterman Creek IA 06-LSR-1621

mouth (S4 T95N R39W O'Brien Co.) to headwaters in S15 T96N R40W O'Brien Co.

This is a DRAFT assessment
Draft assessments may change without notice
Cycle
2026
Current Phase
Public Comment
Overall IR
3 - Insufficient data exist to determine whether any designated uses are met.
Trend
Declining
Trend Comment
New presumptive Class BWW1 benthic macroinvertebrate WINOFI listing (potential impairment).
Created
10/27/2025 3:08:47 PM
Updated
2/11/2026 9:39:27 AM
Use Support
Class A1
Recreation - Primary contact
Not Assessed
Class BWW1
Aquatic Life - Warm Water Type 1
WINOFI
Impairment Code
3b-u - Use potentially biologically impaired based on uncalibrated IBI metrics.
Cause Magnitude
Slight
Status
New
Source
Unknown: Source Unknown
Source Confidence
Low
Cycle Added
2026
Impairment Rationale
Potential Impairment
Data Source
Biological monitoring: Iowa DNR WQMA
Impairment Delistings
No delistings for this assessment cycle.
Documentation
Assessment Summary

The presumptive Class BWW1 use was assessed as “WINOFI” based on biological sampling data. All other designated uses were "not assessed."

Assessment Explanation

Data Source:

Data Source

Data Source ID

Data Type

Data Age

Site ID

Site Name

Site Description

Iowa DNR

6

BIO

See Below

50

Little Waterman Creek

Waterman Creek SWMA -Hartley


Presumptive Class A1 – No Data

Presumptive Class BWW1 - Biological Sampling:

Benthic Macroinvertebrates:

Site ID

Date

Drainage Area (mi2)

Ecoregion

Major Drainage

BM Sample Gear

BMIBI score

BMIBI Class

47a BMIBI BIT

BMIBI Pass/Fail

50

9/16/24

17.1

47a

MO

Surber

52

Fair

54

Fail

50

8/23/23

17.1

47a

MO

Surber

51

Fair

54

Fail

50

7/27/22

17.1

47a

MO

Surber

47

Fair

54

Fail

50

7/20/21

17.1

47a

MO

Surber

63

Good

54

Pass

50

8/5/20

17.1

47a

MO

Surber

55

Fair

54

Pass


Fish:

Site ID

Date

Drainage Area (mi2)

Ecoregion

Major Drainage

Riffle Stream?

FIBI score

FIBI Class

47a FIBI BIT

FIBI Pass/Fail

50

9/16/24

17.1

47a

MO

NA

58

Good

43

Pass

50

8/23/23

17.1

47a

MO

NA

55

Good

43

Pass

50

7/27/22

17.1

47a

MO

NA

59

Good

43

Pass

50

7/20/21

17.1

47a

MO

NA

46

Fair

43

Pass

50

8/5/20

17.1

47a

MO

NA

47

Fair

43

Pass


Overall:

Community

Assessment Type

Assessment Result

Support Level

IR Category

Reason

Benthic Macroinvertebrates

Evaluated

Fail (2/5)

WINOFI

Fish

Evaluated

Pass (5/5)

Full

Assessment was evaluated because the drainage area of

Overall

Evaluated

Fail

WINOFI

3bu

the sample site was smaller than the calibrated range.

Monitoring and Methods
Assessment Key Dates
7/27/2022
Biological Monitoring
8/23/2023
Biological Monitoring
7/20/2021
Biological Monitoring
9/16/2024
Biological Monitoring
8/5/2020
Biological Monitoring
Methods
315
Regional reference site approach
320
Benthic macroinvertebrate surveys
330
Fish surveys