Iowa DNR
Iowa DNR
ADBNet
Water Quality Assessments
Impaired Waters List

Little Maquoketa River IA 01-TRK-131

mouth (Dubuque Co.) to confluence with Hogans Br. in S36 T89N R1W Dubuque 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
12/2/2025 11:17:33 AM
Use Support
Class A1
Recreation - Primary contact
Not Assessed
Class BWW1
Aquatic Life - Warm Water Type 1
Not Supported
Support Level
Not Supported
Impairment Code
5b-v - Biological - verified
Cause Magnitude
Slight
Status
Continuing
Source
Unknown: Source Unknown
Source Confidence
N/A
Cycle Added
2022
Impairment Rationale
Low Biotic Index
Data Source
Biological monitoring: Iowa DNR WQMA
TMDL Priority
Tier IV
Class HH
Human Health -
Not Assessed
Impairment Delistings
No delistings for this assessment cycle.
Documentation
Assessment Summary

The Class BWW1 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

See Below

40

Little Maquoketa River

Twin Springs Road - Dubuque


Presumptive Class A1 – No Data

Class BWW1 - 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

40

8/20/24

46

52b

MS

Hess

67

Good

61

Pass

40

7/22/20

46

52b

MS

Hess

58

Good

61

Fail


Fish:

Site ID

Date

Drainage Area (mi2)

Ecoregion

Major Drainage

Riffle Stream?

FIBI score

FIBI Class

52b FIBI BIT

FIBI Pass/Fail

40

8/20/24

46

52b

MS

NA

62

Good

52

Pass

40

7/22/20

46

52b

MS

NA

65

Good

52

Pass


Overall:

Community

Assessment Type

Assessment Result

Support Level

IR Category

Reason

Benthic Macroinvertebrates

Evaluated

Fail (1/2)

Not

Assessment was evaluated because even though the samples

Fish

Monitored

Pass (2/2)

Full

used to complete the assessment were collected in a recent

Overall

Evaluated

Fail

Not

5bv

five-year period, the BMIBI assessment was inconclusive.


Class HH – No Data

Monitoring and Methods
Assessment Key Dates
7/22/2020
Biological Monitoring
8/20/2024
Biological Monitoring
Methods
315
Regional reference site approach
320
Benthic macroinvertebrate surveys
330
Fish surveys