Iowa DNR
Iowa DNR

ADBNet

Water Quality Assessments
Impaired Waters List

Middle Fork Little Maquoketa River IA 01-TRK-138

Alternate name(s) for this segment: Bankston Creek

from west line of S31 T90N R1E (Dubuque Co.) to north line of S33 T90N R1W Dubuque Co.

This is a DRAFT assessment
Draft assessments may change without notice
Overall IR
5 - Water is impaired or threatened and a TMDL is needed.
Trend
Stable
Current Phase
Public Comment
Created
10/27/2025 3:09:02 PM by
Updated
1/9/2026 12:36:52 PM by
Use Support
Class A1
Recreation - Primary contact
Not Assessed
Class A2
Recreation - Secondary contact
Not Assessed
Class BCW1
Aquatic Life - Cold Water Type 1
Not Supported
Support Level
Not Supported
Impairment Code
5b-v - Biological - verified
Cause Magnitude
Moderate
303(d) Listing Status
Continuing
Source
Unknown: Source Unknown
Source Confidence
Low
Cycle Added
2006
Impairment Rationale
Low Biotic Index
Data Source
Biological monitoring: Iowa DNR WQMA
TMDL Priority
Tier IV
Class HH
Human Health -
Not Assessed
No delistings for this assessment cycle.
Documentation
Assessment Summary

The Class BCW1 use was assessed as "not supported" based on 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

419

Middle Fork Little Maquoketa River

Rickardsville – REMAP #261


Presumptive Class A1 - No Data

Class A2 - No Data

Class HH - No Data

Class BCW1 - Biological Sampling:

Benthic Macroinvertebrates:

BioNet Site ID

Date

Drainage Area (mi2)

Ecoregion

Major Drainage/Thermal

BM Sample Gear

CBI score

CBI Class

CBI BIT

CBI Pass/Fail

419

8/31/16

13

52b

MS/CW

Hess

45

NA

60

Fail

419

7/18/16

13

52b

MS/CW

Hess

49

NA

60

Fail


Overall Assessment:

Community

Assessment Type

Assessment Result

Support Level

IR Category

Reason

Benthic Macroinvertebrates

Evaluated

Fail (0/2)

Not

5bv

Assessment was evaluated because it was based on samples not collected in a recent five-year period.


Class BCW1 – Continuous DO Monitoring: 2016

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

4/12

No

419

6

72

16 hr

0/12

No

Evaluated

Full


Aquatic Life Use - Trout Natural Reproduction

Based on the latest trout reproduction in Iowa streams summary prepared by the DNR Fisheries Bureau, the aquatic life use was assessed as "fully supported." According to the summary, a portion, or all, of this assessment unit was placed in Category I: streams that exhibit consistent natural reproduction and maintain a wild population of one or more trout species without any stocking.

Monitoring and Methods
Assessment Key Dates
7/18/2016
Biological Monitoring
8/31/2016
Biological Monitoring
1/1/2025
Biological Monitoring
7/18/2016
Monitoring Start
8/31/2016
Monitoring End
Methods
315
Regional reference site approach
320
Benthic macroinvertebrate surveys
330
Fish surveys