Yellow River IA 01-YEL-2060

from confluence with unnamed tributary in SE 1/4 S8 T96N R7W to headwaters (T96N R8W Sec3 Winneshiek Co.)

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 2020 - 2022
Stream/River Water Quality Data	CY 2020 - 2022
Lake Water Quality Data	CY 2018 - 2022
Biological Sampling Data	CY 2018 - 2022*
Fish Kill Data	CY 2018 - 2022
Fish Tissue Sampling Data	CY 2018 - 2022
Continuous Dissolved Oxygen Sampling Data	CY 2018 - 2022
*Biological sites sampled in both 2017 and 2021 were also assessed.

Open Segment Map
View assessment methodology in new window

Cycle: 2024
Release Status: Final
Overall IR: 5 - Water is impaired or threatened and a TMDL is needed.
Trend: Unknown
Created: 11/1/2023 8:13:28 AM
Updated: 12/27/2023 11:46:25 AM

Use Support

Class A1

Presumptive Use

Recreation - Primary contact

Not Supported

Bacteria: Indicator Bacteria- E. coli

Support Level

Not Supported

Impairment Code

5p - Impairment occurs on a waterbody with a presumptive A1 or B(WW1) use.

Cause Magnitude

High

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2014

Impairment Rationale

Geometric mean criterion exceeded

Data Source

Special project/study: Iowa DNR

TMDL Priority

Tier III

Class BWW1

Presumptive Use

Aquatic Life - Warm Water Type 1

Fully Supported

Impairment Delistings

Cycle Added	Class	Cause	Data Source	Rationale
2016	Class A1	pH	Ambient monitoring: Iowa DNR-rivers	New data: WQ improvement (chemical / physical / bacterial)
2014	Class BWW1	pH	Ambient monitoring: Iowa DNR-rivers	New data: WQ improvement (chemical / physical / bacterial)

Documentation

Assessment Summary

The presumptive Class A1 use was assessed as "not supported” based on violations of water quality criteria for indicator bacteria (E. coli). The presumptive Class BWW1 use was assessed as “fully supported” based on water quality monitoring data.

Assessment Explanation

Data Sources:

Data Source	Data Source ID	Data Type	Data Age	Site ID	Site Name	Site Description
Iowa DNR	6	WQ	CY 2014, CY 2021-2022	11960008	Yellow River near Castalia	Site YeRi5
Iowa DNR	6	WQ	CY 2014	15960042	Yellow River at Sand Rd	Site 9

Presumptive Class A1 - Indicator Bacteria: CY 2014

Site ID	Data Source ID	# Samples / # Years	2014 Geometric Mean	Annual Geometric Mean Violation	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
11960008	6	20 / 1	736	Yes	15	75%	Yes	Evaluated	Not
15960042	6	19 / 1	1092	Yes	17	89%	Yes	Evaluated	Not

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
11960008	6	10 / 2	7.69	8.07	7.88	0	3	NO	Mon	Full

Presumptive 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
11960008	6	Dissolved Oxygen	10 / 2	8.28	12.58	10.36	0	NA / NA	3	NO	Mon	Full
11960008	6	pH	10 / 2	7.69	8.07	7.88	0	NA / NA	3	NO	Mon	Full
11960008	6	Temperature	10 / 2	5.636	21.957	15.369	0	NA / NA	3	NO	Mon	Full

Monitoring and Methods

Assessment Key Dates

4/22/2014

Monitoring Start

10/8/2014

Monitoring End

5/21/2021

Monitoring Start

9/12/2022

Monitoring End

Methods

150

Monitoring data more than 5 years old

200

Physical/Chemical Monitoring

420

Indicator bacteria monitoring