Iowa DNR
Iowa DNR

ADBNet

Water Quality Assessments
Impaired Waters List

Little Cedar River IA 02-CED-579

from dam of impoundment at Stacyville (SE 1/4 S31 T100N R16W Mitchell Co.) to the Iowa/Minnesota state line at N line S9 T100N R16W Mitchell Co.

This is a DRAFT assessment
Draft assessments may change without notice
Overall IR
2 - Some of the designated uses are met but there is insufficient data to determine if remaining designated uses are met.
Trend
Stable
Current Phase
Public Comment
Created
10/27/2025 3:10:03 PM by
Updated
1/7/2026 10:32:41 AM by
Use Support
Class A1
Recreation - Primary contact
WINOFI
Impairment Code
3b - Use potentially impaired based on an evaluated assessment.
Cause Magnitude
Moderate
303(d) Listing Status
Continuing
Source
Unknown: Source Unknown
Source Confidence
N/A
Cycle Added
2016
Impairment Rationale
Potential Impairment
Data Source
Ambient monitoring: adjacent state
Class BWW1
Aquatic Life - Warm Water Type 1
Fully Supported
Class HH
Human Health -
Not Assessed
No delistings for this assessment cycle.
Documentation
Assessment Summary

The presumptive Class A1 (primary contact recreation) use remains assessed as "WINOFI" due to the impairment for indicator bacteria (E. coli) in the adjacent upstream segment by the Minnesota Pollution Control Agency (MPCA) in 2012. MPCA finalized a TMDL for the E. coli impairment in 2019. The Class BWW1 use was assessed as "fully supported" based on water quality monitoring 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

MNPCA

15

WQ

CY 2018-2020

99990104

Little Cedar River


Presumptive Class A1:

The presumptive Class A1 (primary contact recreation) uses are assessed as "WINOFI" due to the identification of an impairment for indicator bacteria (E. coli) in the adjacent upstream segment by the Minnesota Pollution Control Agency (MPCA) in 2012. MPCA finalized a TMDL for the E. coli impairment in 2019.

Presumptive Class A1 – pH:

Site ID

Data Source ID

# Samples / # Years

Minimum Value

Maximum Value

Mean Value

# Violations

Violations needed for impairment

Violates Significantly >10% Rule?

Assessment Type

Support Level

99990104

15

28 / 3

6.94

8.38

7.9

0

6

NO

Monitored

Full

Class BWW1 - Binomial Parameters:

Site ID

Data Source ID

Parameter Name

# Samples / # Years

Minimum Value

Maximum Value

Mean Value

# Violations

# Acute / Chronic Violations

Violations needed for impairment

Violates Significantly >10% Rule?

Assessment Type

Support Level

99990104

15

Dissolved Oxygen

28 / 3

6.55

13.93

9.48

0

NA / NA

6

NO

Monitored

Full

99990104

15

pH

28 / 3

6.94

8.38

7.9

0

NA / NA

6

NO

Monitored

Full

99990104

15

Temperature

28 / 3

6.38

24

18.11

0

NA / NA

6

NO

Monitored

Full

Class HH - No Data

Monitoring and Methods
Assessment Key Dates
4/26/2018
Monitoring Start
9/9/2020
Monitoring End
Methods
200
Physical/Chemical Monitoring
420
Indicator bacteria monitoring
860
Other Agencies/Organizations provided monitoring data