Yellow River IA 01-YEL-436

from old Hwy 51 crossing (NE 1/4 S11 T96N R6W Allamakee Co.) to confluence with N. Fk. Yellow R. in S13 T96N R7W Winneshiek Co.

This is a DRAFT assessment

Draft assessments may change without notice

Open Data Collection Period Modal

For purposes of developing stream/river water quality assessments for integrated reporting, three years of water quality data are typically used for both conventional pollutant parameters (e.g., indicator bacteria) and the less frequently monitored toxic parameters (e.g., toxic metals). Since the 2004 IR cycle, DNR has used a three-year data gathering period for streams, rivers, and beaches. For most assessments, the use of three years of data increases the number of samples upon which the decision on use support is based and helps address the problem of weather-related year-to-year fluctuations in water quality.

Due to the lower sampling frequency in Iowa’s ambient lake, biological, fish kill, and fish tissue monitoring programs, five years of data are used for developing IR assessments and for identifying Section 303(d) listings.

Data Type	Data Timeframe
Beach Sampling Data	CY 2022 - 2024
Stream/River Water Quality Data	CY 2022 - 2024
Lake Water Quality Data	CY 2020 - 2024
Biological Sampling Data	CY 2020 - 2024*
Fish Kill Data	CY 2020 - 2024
Fish Tissue Sampling Data	CY 2020 - 2024
Continuous Dissolved Oxygen Sampling Data	CY 2020 - 2024
*Biological sites sampled in both 2019 and 2023 were also assessed.

Open Segment Map
View 2026 assessment summary page

Cycle: 2026
Current Phase: Public Comment
Overall IR: 5 - Water is impaired or threatened and a TMDL is needed.
Trend: Stable
Created: 11/25/2025 8:22:26 AM
Updated: 1/6/2026 10:00:28 AM

Use Support

Class A1

Presumptive Use

Recreation - Primary contact

Not Supported

Bacteria: Indicator Bacteria- E. coli

Support Level

Not Supported

Impairment Code

4a - Pollutant-caused impairment. TMDL has been completed.

Cause Magnitude

High

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2008

Impairment Rationale

Geometric mean criterion exceeded

Data Source

Watershed project monitoring

Class A2

Recreation - Secondary contact

Not Supported

Bacteria: Indicator Bacteria- E. coli

Support Level

Not Supported

Impairment Code

4a - Pollutant-caused impairment. TMDL has been completed.

Cause Magnitude

High

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2002

Impairment Rationale

Geometric mean criterion exceeded

Data Source

Watershed project monitoring

Class BCW1

Aquatic Life - Cold Water Type 1

Not Supported

Fish Kill: Due To Unknown Toxicity

Support Level

Not Supported

Impairment Code

5b - Biological impairment or pollutant-caused fish kill - unknown source. No administrative action.

Cause Magnitude

Moderate

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2016

Impairment Rationale

Pollutant-caused fish kill

Data Source

Fish kill investigation: Iowa DNR

TMDL Priority

Tier IV

Class HH

Human Health -

Not Assessed

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The presumptive Class A1 use and Class A2 use were assessed as “not supported” due to levels of indicator bacteria (E. coli) that exceeded state water quality criteria. The Class BCW1 use was assessed as "not supported" based on a fish kill investigation. All other designated uses were "not assessed." Note: A TMDL for the bacteria impairment for Yellow River basin streams was approved by U.S. EPA in 2013. Due to TMDL completion, the Integrated Report categories for the Class A1 and Class A2 recreational uses were changed from 5p to 4a.

Assessment Explanation

Data Sources:

Data Source	Data Source ID	Data Type	Data Age	Site ID	Site Name	Site Description
Iowa DNR	6	WQ	CY 2009	11030001	Yellow River	Mainstem 1

Presumptive Class A1 - Indicator Bacteria: 2009

Site ID	Data Source ID	# Samples / # Years	2009 Geometric Mean	Annual Geometric Mean Violation	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
11030001	6	13 / 1	13288	Yes	13	100%	Yes	Evaluated	Not

Class A2 - Indicator Bacteria: 2009

Site ID	Data Source ID	# Samples / # Years	2009 Geometric Mean	Annual Geometric Mean Violation	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
11030001	6	13 / 1	13288	Yes	9	69%	Yes	Evaluated	Not

Class BCW1 – Fishkill Assessment:

The Class BCW1 use assessment based on the 2000 fish kill placed this segment in Category 5b. The fish kill was caused by a “pollutant” or was suspected to be caused by a “pollutant”; therefore, the Class BCW1 use was considered impaired. Because the source of the pollutant was not identified and/or the enforcement actions taken against the responsible party have not been resolved, the Class BCW1 use was placed in Category 5b. Due to uncertainty regarding the recovery of the aquatic life following the fish kill, any existing fish kill 5b impairment will remain in Category 5b until more recent sampling has shown recovery of the aquatic community or the responsible party has paid restitution.

Details about the 2000 fish kill can be found here: https://programs.iowadnr.gov/fishkill/Events/462

Class HH – No Data

Monitoring and Methods

Assessment Key Dates

3/17/2000

Fish Kill

5/20/2009

Monitoring Start

7/13/2009

Monitoring End

2/1/2013

TMDL Completed

Methods

120

Surveys of fish and game biologists/other professionals

140

Incidence of spills and/or fish kills

150

Monitoring data more than 5 years old

420

Indicator bacteria monitoring