North Fork Yellow River IA 01-YEL-448

mouth (S13 T96N R7W Winneshiek Co.) to confluence with unnamed tributary in S3 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 2016 - 2018
Stream/River Water Quality Data	CY 2016 - 2018
Lake Water Quality Data	CY 2014 - 2018
Biological Sampling Data	CY 2014 - 2018*
Fish Kill Data	CY 2014 - 2018
Fish Tissue Sampling Data	CY 2014 - 2018
Continuous Dissolved Oxygen Sampling Data	CY 2014 - 2018
*Biological sites sampled in both 2013 and 2017 were also assessed.

Open Segment Map
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Cycle: 2020
Release Status: Final
Overall IR: 5 - Water is impaired or threatened and a TMDL is needed.
Trend: Unknown
Created: 10/5/2020 2:49:31 PM
Updated: 10/16/2020 7:24:25 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 BWW2

Aquatic Life - Warm Water Type 2

Partially Supported

Organic Enrichment: Low Dissolved Oxygen

Support Level

Partially Supported

Impairment Code

5a - Pollutant-caused impairment. TMDL needed.

Cause Magnitude

Moderate

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2008

Impairment Rationale

Significantly > 10% of samples fail to meet criterion

Data Source

Watershed project monitoring

TMDL Priority

Tier IV

General Use

General Use water -

Not Assessed

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The presumptive Class A1 use remains assessed as “not supported” due to levels of indicator bacteria (E. coli) that exceeded state water quality criteria. The Class BWW2 use remains assessed as "partially supported" due to violations of criteria for dissolved oxygen. Note: A TMDL for the bacteria impairment for streams in the Yellow River basin was prepared by Iowa DNR in 2012 and was approved by U.S. EPA in February 2013. Due to completion of the TMDL, the Integrated Report category for the Class A1 recreational uses is changed from 5p (impaired; TMDL needed) to 4a (impaired; TMDL approved). Because not all impairments identified for this assessment segment are covered by the TMDL (biological impairment of the aquatic life uses due to low dissolved oxygen), this segment remains in Category 5a of Iowa's Integrated Report (impaired and TMDL required).

Assessment Explanation

Sources of Data:

Data Source	Data Source ID	Data Type	Data Age	Site ID	BioNet Site ID	Site Name	Site Description
Iowa DNR	6	WQ	CY 2014	15960034		North Fork Yellow River at 111th Ave (Site 1)	Class A1
Iowa DNR	6	WQ	CY 2011	15960034		North Fork Yellow River at 111th Ave (Site 1)	Class BWW2

Presumptive Class A1 - Indicator Bacteria: Historical

Site ID	Data Source ID	# Samples / # Years	2014 Geometric Mean	Annual Geometric Mean Violation	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
15960034	6	20 / 1	5621	Yes	19	95%	Yes	Evaluated	Not

Class BWW2 - Conventional Parameters: Historical

Site ID	Data Source ID	Parameter Name	# Samples / # Years	Maximum Value	Mean Value	Median Value	# Acute / Chronic Violations	% Acute/ Chronic Violations	Significantly >10% Violations	Assessment Type	Support Level
15030011	6	Ammonia	8 / 1	0.25	0.07	0.05	0 / 0	0% / 0%	No	Evaluated	Full
15030011	6	Chloride	14 / 1	33	33	33	0 / 0	0% / 0%	No	Evaluated	Full
15030011	6	Dissolved oxygen	14 / 1	13.6	8.4	7.25	NA / 0	NA / 0%	No	Evaluated	Full
15030011	6	Temperature	14 / 1	22.2	13.8	14.3	0 / 0	0% / 0%	No	Evaluated	Full

The Class BW2 aquatic life uses remain assessed as “partially supported” due to violations of aquatic life criteria for dissolved oxygen at station 15960001 during the 2004-06 monitoring period. Based on DNR's assessment methodology, however, two consecutive assessment/listing cycles without significantly greater than 10% of the samples violating the standard are necessary to justify the de-listing of an impairment due to low dissolved oxygen. Therefore, the impairment for dissolved oxygen will remain.

Monitoring and Methods

Assessment Key Dates

4/18/2011

Non-fixed Monitoring Start Date

10/25/2011

Non-fixed Monitoring End Date

4/22/2014

Non-fixed Monitoring Start Date

10/8/2014

Non-fixed Monitoring End Date

Methods

150

Monitoring data more than 5 years old

220

Non-fixed station physical/chemical monitoring (conventional pollutant only)

420

Indicator bacteria monitoring