Iowa DNR
Iowa DNR

ADBNet

Water Quality Assessments
Impaired Waters List

Duck Creek IA 01-UIA-254

mouth (NE 1/4 S14 T100N R6W Allamakee Co.) to IA/MN state line (S11 T100N R6W Allamakee 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
Unknown
Current Phase
Public Comment
Created
10/27/2025 3:10:43 PM by
Updated
1/2/2026 3:26:03 PM by
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
303(d) Listing Status
Continuing
Source
Unknown: Source Unknown
Source Confidence
N/A
Cycle Added
2014
Impairment Rationale
Geometric mean criterion exceeded
Data Source
Watershed project monitoring
TMDL Priority
Tier III
Class BWW1
Aquatic Life - Warm Water Type 1
Fully Supported
No delistings for this assessment cycle.
Documentation
Assessment Summary

The presumptive Class A1 use was assessed as “not supported” due to violations of Iowa water quality criteria for indicator bacteria (E. coli). The presumptive Class BWW1 use was assessed as "fully supported" based on the trout reproduction in Iowa streams summary prepared by the DNR Fisheries Bureau. Although not designated for coldwater aquatic life uses in the Iowa Water Quality Standards/Surface Water Classification, this stream is considered a trout stream by the DNR Fisheries Bureau and is identified as an "Outstanding Iowa Water" as part of Iowa's anti-degradation program. Thus, this stream segment is assessed as a coldwater stream for the Iowa’s Integrated Reporting cycle.

Assessment Explanation

Data Sources:

Data Source

Data Source ID

Data Type

Data Age

Site ID

Site Name

Site Description

Iowa DNR

6

WQ

CY 2010-2011

13030001

Duck Creek at Waterloo Creek Dr (Site Duck 1)


Presumptive Class A1 - Indicator Bacteria: Historical

Site ID

Data Source ID

# Samples / # Years

2010 Geometric Mean

2011 Geometric Mean

Annual Geometric Mean Violation

# Violations

% Violations

Significantly >10% Violations

Assessment Type

Support Level

13030001

6

30 / 2

530

90

Yes

16

53%

Yes

Evaluated

Not


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 both Category I: streams that exhibit consistent natural reproduction and maintain a wild population of one or more trout species without any stocking and in Category II: streams that exhibit recent but inconsistent reproductive success of one or more trout species.

Monitoring and Methods
Assessment Key Dates
4/20/2010
Monitoring Start
11/1/2011
Monitoring End
1/1/2025
Biological Monitoring
Methods
120
Surveys of fish and game biologists/other professionals
330
Fish surveys
420
Indicator bacteria monitoring