East Branch Iowa River IA 02-IOW-771

from confluence with Ditch No. 9 (S31 T95N R23W Hancock Co.) to confluence with unnamed tributary at Garner in SE 1/4 S25 T96N R24W Hancock 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 2018 - 2020
Stream/River Water Quality Data	CY 2018 - 2020
Lake Water Quality Data	CY 2016 - 2020
Biological Sampling Data	CY 2016 - 2020*
Fish Kill Data	CY 2016 - 2020
Fish Tissue Sampling Data	CY 2016 - 2020
Continuous Dissolved Oxygen Sampling Data	CY 2016 - 2020
*Biological sites sampled in both 2015 and 2019 were also assessed.

Open Segment Map
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Cycle: 2022
Release Status: Final
Overall IR: 4 - Water is impaired or threatened and a TMDL has been completed or is not needed.
Trend: Unknown
Created: 1/10/2022 2:47:47 PM
Updated: 2/9/2022 11:54:57 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

Moderate

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2012

Impairment Rationale

Geometric mean criterion exceeded

Data Source

Special project/study

Class BWW2

Aquatic Life - Warm Water Type 2

Fully Supported

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The presumptive Class A1 use was assessed as “not supported” due to violations of Iowa water quality criteria for indicator bacteria (E. coli). The Class BWW2 use remains assessed as “fully supported” based on water quality monitoring data. Note: A TMDL covering the bacteria impairments for all segments, with the segment code prefix "IA 02-IOW" in the Iowa River Basin, was approved by EPA in 2018. Due to the completion of the TMDL, the IR category for the Class A1 use was changed from 5p (impaired; TMDL needed) to 4a (impaired; TMDL approved).

Assessment Explanation

Data Sources:

Data Source	Data Source ID	Data Type	Data Age	Site ID	Site Name	Site Description
Iowa DNR	6	WQ	CY 2010-2012	13410001	East Branch Iowa River near Garner	Upstream
Iowa DNR	6	WQ	CY 2010-2012	13410009	East Branch Iowa River at 200	Site 5a
Iowa DNR	6	WQ	CY 2010	13410010	East Branch Iowa River at 190	Site 6
Iowa DNR	6	WQ	CY 2010	13410011	East Branch Iowa River at Hwy 69	Site 7

Presumptive Class A1 - Indicator Bacteria:

Site ID	Data Source ID	# Samples / # Years	2010 Geometric Mean	2011 Geometric Mean	2012 Geometric Mean	Annual Geometric Mean Violation	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
13410001	6	35 / 3	534	408	129	Yes	23	66%	Yes	Evaluated	Not
13410009	6	32 / 3	713	448	117	Yes	21	66%	Yes	Evaluated	Not
13410010	6	10 / 1	794	NA	NA	Yes	9	90%	Yes	Evaluated	Not
13410011	6	9 / 1	483	NA	NA	Yes	7	78%	Yes	Evaluated	Not

Presumptive Class A1 - pH:

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
13410001	6	pH	13 / 1	8.8	8.5	8.6	0 / 0	0% / 0%	No	Evaluated	Full
13410009	6	pH	13 / 1	9.3	8.7	8.7	1 / 0	8% / 0%	No	Evaluated	Full

Class BWW2 – Conventional Parameters

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
13410001	6	Ammonia	11 / 1	0.15	0.08	0.05	0 / 0	0% / 0%	No	Evaluated	Full
13410001	6	Dissolved oxygen	13 / 1	14.8	8.4	8	NA / 0	NA / 0%	No	Evaluated	Full
13410001	6	pH	13 / 1	8.8	8.5	8.6	0 / NA	0% / NA	No	Evaluated	Full
13410001	6	Temperature	13 / 1	31.2	19.3	20.4	0 / 0	0% / 0%	No	Evaluated	Full
13410009	6	Ammonia	9 / 1	0.05	0.05	0.05	0 / 0	0% / 0%	No	Evaluated	Full
13410009	6	Dissolved oxygen	13 / 1	14.7	9	8.6	NA / 0	NA / 0%	No	Evaluated	Full
13410009	6	pH	13 / 1	9.3	8.7	8.7	1 / NA	8% / NA	No	Evaluated	Full
13410009	6	Temperature	13 / 1	31.4	19.7	21.4	0 / 0	0% / 0%	No	Evaluated	Full

Monitoring and Methods

Assessment Key Dates

6/2/2010

Non-fixed Monitoring Start Date

11/14/2012

Non-fixed Monitoring End Date

3/9/2018

TMDL Completed

Methods

150

Monitoring data more than 5 years old

220

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

420

Indicator bacteria monitoring