Iowa DNR
Iowa DNR
ADBNet
Water Quality Assessments
Impaired Waters List

Cedar River IA 02-CED-457

from confluence with Bear Cr. (NE 1/4 S21 T84N R8W Linn Co.) to confluence with Hinkle Cr. in SW 1/4 S16 T85N R10W Benton 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
Stable
Created
10/27/2025 3:09:32 PM
Updated
2/11/2026 9:32:06 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
Continuing
Source
Unknown: Source Unknown
Source Confidence
Low
Cycle Added
2014
Impairment Rationale
Potential Impairment
Data Source
Biological monitoring: Iowa DNR WQMA
Class HH
Human Health -
Not Assessed
Impairment Delistings
No delistings for this assessment cycle.
Documentation
Assessment Summary

The Class BWW1 use was assessed as "WINOFI" 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

WQ

CY 2022

14000349

Cedar River

Iowa DNR6BIOSee Below869Cedar RiverPalo (dstr of DAEC)


Class A1 - Indicator Bacteria: No Data

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

14000349

6

7 / 1

8.08

8.77

8.53

0

3

NO

EVALUATED

FULL


Class HH: No Data

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

14000349

6

Dissolved Oxygen

7 / 1

8

15.5

12.4

0

NA / NA

3

NO

EVALUATED

FULL

14000349

6

pH

7 / 1

8.08

8.77

8.53

0

NA / NA

3

NO

EVALUATED

FULL

14000349

6

Temperature

7 / 1

7.24

25.93

18.95

0

NA / NA

3

NO

EVALUATED

FULL


Class BWW1 - Biological Sampling:

Benthic Macroinvertebrates:

BioNet Site ID

Date

Drainage Area (mi2)

Ecoregion

Major Drainage

BM Sample Gear

BMIBI score

BMIBI Class

47c BMIBI BIT

BMIBI Pass/Fail

869

10/7/11

6238

47c

MS

Hess

45

Fair

70

Fail


Overall Assessment:

Community

Assessment Type

Assessment Result

Support Level

IR Category

Reason

Benthic Macroinvertebrates

Evaluated

Fail (0/1)

WINOFI

3bu

Assessment was evaluated because the drainage area of the site was larger than the calibrated range.

Monitoring and Methods
Assessment Key Dates
10/7/2011
Biological Monitoring
4/20/2022
Monitoring Start
10/17/2022
Monitoring End
Methods
150
Monitoring data more than 5 years old
200
Physical/Chemical Monitoring
315
Regional reference site approach
320
Benthic macroinvertebrate surveys