Unnamed Tributary to Yellow River IA 01-YEL-2059

mouth (S14 T96N R7W Winneshiek Co.) to headwaters in NW1/4 S26 T96N. R7W 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
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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 8:11:39 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

Watershed project monitoring

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. The presumptive Class BWW1 use was assessed as “fully supported” based on biological sampling data and 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 2021-2022	15960037	Unnamed Creek at 135th St (Site 5)
Iowa DNR	6	BIO	See Below	578	Unnamed Tributary to Yellow River	Castalia – YeRi2

Presumptive Class A1 - Indicator Bacteria: 2021-2022

Site ID

Data Source ID

# Samples per Year (2020/ 2021/2022)

2020 Geometric Mean

2021 Geometric Mean

2022 Geometric Mean

Violates Annual Geometric Mean?

# 2020 SSM violations / SSM Violations needed for impairment

# 2021 SSM violations / SSM Violations needed for impairment

# 2022 SSM violations / SSM Violations needed for impairment

Violates Annual SSM Significantly >10% Rule?

Assessment Type

Support Level

15960037

0/4/6

1763

663

YES

4 / NA

YES

Eval

Not

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
15960037	6	20 / 1	903	Yes	17	85%	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
15960037	6	10 / 2	7.5	8.4	8	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
15960037	6	Dissolved Oxygen	10 / 2	9.11	13.58	10.36	0	NA / NA	3	NO	Mon	Full
15960037	6	pH	10 / 2	7.5	8.4	8	0	NA / NA	3	NO	Mon	Full
15960037	6	Temperature	10 / 2	5.921	20.027	15.667	0	NA / NA	3	NO	Mon	Full

Presumptive Class BWW1 - Biological Sampling:

Benthic Macroinvertebrates:

BioNet Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage/Thermal	BM Sample Gear	BMIBI score	BMIBI Class	52b BMIBI BIT	BMIBI Pass/Fail
578	9/27/22	3.7	52b	MS/WW	Hess	73	Good	61	Pass

Fish:

BioNet Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage/Thermal	Riffle Stream?	FIBI score	FIBI Class	52b FIBI BIT	FIBI Pass/Fail
578	9/27/22	3.7	52b	MS/WW	NA	73	Excellent	52	Pass

Overall:

Community	Assessment Type	Assessment Result	Support Level	IR Category	Reason
Benthic Macroinvertebrates	Evaluated	Pass (1/1)	Full
Fish	Evaluated	Pass (1/1)	Full	1	Assessment was evaluated because it was based on a single sample and the
Overall	Evaluated	Pass	Full		drainage area of the sample site was smaller than the calibrated range.

Monitoring and Methods

Assessment Key Dates

5/20/2021

Monitoring Start

9/12/2022

Monitoring End

4/1/2014

Monitoring Start

10/31/2014

Monitoring End

Methods

150

Monitoring data more than 5 years old

200

Physical/Chemical Monitoring

315

Regional reference site approach

320

Benthic macroinvertebrate surveys

330

Fish surveys

420

Indicator bacteria monitoring