Iowa DNR
Iowa DNR

ADBNet

Water Quality Assessments
Impaired Waters List

Cedar Creek IA 04-RAC-1819

from confluence with Little Cedar Cr. (S15 T90N R34W Pocahontas Co.) to confluence with Drainage Ditch 21 in S7 T91N R33W Pocahontas Co.

This is a DRAFT assessment
Draft assessments may change without notice
Overall IR
3 - Insufficient data exist to determine whether any designated uses are met.
Trend
Unknown
Current Phase
Public Comment
Created
10/27/2025 3:10:16 PM by
Updated
2/5/2026 9:31:11 AM by
Use Support
Class A1
Recreation - Primary contact
Not Assessed
Class BWW1
Aquatic Life - Warm Water Type 1
WINOFI
Impairment Code
3b-c - Use potentially biologically impaired based on calibrated IBI metrics.
Cause Magnitude
Moderate
303(d) Listing Status
Continuing
Source
Unknown: Source Unknown
Source Confidence
Low
Cycle Added
2004
Impairment Rationale
Potential Impairment
Data Source
Biological monitoring: Iowa DNR WQMA
Impairment Code
3b - Use potentially impaired based on an evaluated assessment.
Cause Magnitude
Moderate
303(d) Listing Status
New
Source
Unknown: Source Unknown
Source Confidence
N/A
Cycle Added
2026
Impairment Rationale
Potential Impairment
Data Source
Fish kill investigation: Iowa DNR
No delistings for this assessment cycle.
Documentation
Assessment Summary

The presumptive Class BWW1 use was assessed as "WINOFI" based on biological sampling data and a 2023 fish kill. 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

228

Big Cedar Creek

Fonda


Presumptive Class A1 - No Data

Presumptive Class BWW1 - Biological Sampling:

Benthic Macroinvertebrates:

BioNet Site ID

Date

Drainage Area (mi2)

Ecoregion

Major Drainage

BM Sample Gear

BMIBI score

BMIBI Class

47b BMIBI BIT

BMIBI Pass/Fail

228

9/27/06

81

47b

MS

Hess

38

Fair

62

Fail


Fish:

BioNet Site ID

Date

Drainage Area (mi2)

Ecoregion

Major Drainage

Riffle Stream?

FIBI score

FIBI Class

47b FIBI BIT

FIBI Pass/Fail

228

9/27/06

81

47b

MS

Yes

57

Good

53

Pass


Overall:

Community

Assessment Type

Assessment Result

Support Level

IR Category

Reason

Benthic Macroinvertebrates

Evaluated

Fail (0/1)

WINOFI

Fish

Evaluated

Pass (1/1)

Full

Assessment was evaluated because it was based on samples

Overall

Evaluated

Fail

WINOFI

3bc

on samples not collected in a recent five-year period.


Presumptive Class BWW1 - Fish Kill Assessment:

The presumptive Class BWW1 use assessment based on the 2023 fish kill placed this segment in Category 3b.
This assessment was “evaluated” because there was a single fish kill on this segment in the last five years. Segments assessed using “evaluated” assessments are placed in Category 3b and are added to the state list of Waters In Need Of Further Investigation (WINOFI). If no additional fish kills are reported in this segment for a 5-year period (2024-2028), the category will be changed from 3b to 3a (not assessed).

Details about the 2023 fish kill can be found here:https://programs.iowadnr.gov/fishkill/events/1054

Monitoring and Methods
Assessment Key Dates
9/27/2006
Biological Monitoring
7/17/2023
Fish Kill
Methods
140
Incidence of spills and/or fish kills
150
Monitoring data more than 5 years old
315
Regional reference site approach
320
Benthic macroinvertebrate surveys
330
Fish surveys