Turkey River IA 01-TRK-148

mouth (Clayton Co.) to confluence with Volga R. in S26 T92N R4W Clayton 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: 10/27/2025 3:09:37 PM
Updated: 1/9/2026 11:17:06 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

Slight

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2008

Impairment Rationale

Geometric mean criterion exceeded

Data Source

Ambient monitoring: Iowa DNR-rivers

TMDL Priority

Tier III

Class BWW1

Aquatic Life - Warm Water Type 1

Fully Supported

Class HH

Human Health -

Not Supported

Fish Consumption Advisory: Mercury

Support Level

Not Supported

Impairment Code

5a - Pollutant-caused impairment. TMDL needed.

Cause Magnitude

Slight

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2014

Impairment Rationale

Fish consumption advisory in effect: no more than 1 meal/week

Data Source

Fish contaminant monitoring: Iowa DNR

TMDL Priority

Tier IV

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The presumptive Class A1 use was assessed as "not supported" due to levels of indicator bacteria (E. coli) that exceeded state water quality criteria. The Class BWW1 use was assessed as "fully supported" based on biological sampling data and water quality monitoring data. The Class HH use remains assessed as "not supported" based on fish tissue sampling data and the historic existence of a one meal per week mercury consumption advisory.

Assessment Explanation

Data Sources:

Data Source	Data Source ID	Data Type	Data Age	Site ID	Site Name	Site Description
Iowa DNR	6	WQ	CY 2022-2024	10220001	Turkey River at Garber
Iowa DNR	6	BIO	See Below	390	Turkey River	Garber – REMAP #70
Iowa DNR	6	BIO	See Below	840	Turkey River	Garber
Iowa DNR	6	FT	See Below	1124	Turkey River	S of Garber

Presumptive Class A1 - Indicator Bacteria:

Site ID

Data Source ID

# Samples per Year (2022/ 2023/2024)

2022 Geometric Mean

2023 Geometric Mean

2024 Geometric Mean

Violates Annual Geometric Mean?

# 2022 SSM violations / SSM Violations needed for impairment

# 2023 SSM violations / SSM Violations needed for impairment

# 2024 SSM violations / SSM Violations needed for impairment

Violates Annual SSM Significantly >10% Rule?

Assessment Type

Support Level

10220001

8/8/8

176

207

YES

4 / 3

1 / 3

4 / 3

YES

MONITORED

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
10220001	6	35 / 3	7.9	8.5	8.2	0	7	NO	MONITORED	FULL

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
10220001	6	Chloride	36 / 3	7.7	30	17.9	NA	0 / 0	7	NO	MONITORED	FULL
10220001	6	Dissolved Oxygen	36 / 3	7.6	15.2	11.4	0	NA / NA	7	NO	MONITORED	FULL
10220001	6	pH	35 / 3	7.9	8.5	8.2	0	NA / NA	7	NO	MONITORED	FULL
10220001	6	Sulfate	36 / 3	8.7	27	20.6	0	NA / NA	7	NO	MONITORED	FULL
10220001	6	Temperature	36 / 3	0	25.8	12.1	0	NA / NA	7	NO	MONITORED	FULL

Class BWW1 - Toxic Parameters:

Site ID	Data Source ID	Parameter Name	# Samples / # Years	Maximum Value	Mean Value	Median Value	# Acute / Chronic Violations	>1 Acute / Chronic Violation	Assessment Type	Support Level
10220001	6	Ammonia	35 / 3	0.47	0.05	0.02	0 / 0	NO	MONITORED	FULL
10220001	6	Cadmium	18 / 2	0.5	0.5	0.5	0 / 0	NO	MONITORED	FULL
10220001	6	Chromium	18 / 2	10	1.8	1	0 / 0	NO	MONITORED	FULL
10220001	6	Copper	18 / 2	6.3	1.4	1	0 / 0	NO	MONITORED	FULL
10220001	6	Lead	18 / 2	2.5	1.1	1	0 / 0	NO	MONITORED	FULL
10220001	6	Nickel	18 / 2	3.5	1	0.9	0 / 0	NO	MONITORED	FULL
10220001	6	Selenium	36 / 3	1.5	0.7	0.5	0 / 0	NO	MONITORED	FULL
10220001	6	Silver	18 / 2	1	1	1	0 / 0	NO	MONITORED	FULL
10220001	6	Zinc	18 / 2	8	1.3	0.5	0 / 0	NO	MONITORED	FULL

Class BWW1 - Biological Sampling:

Benthic Macroinvertebrates:

Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage	BM Sample Gear	BMIBI score	BMIBI Class	52b BMIBI BIT	BMIBI Pass/Fail
840	10/6/21	1553.3	52b	MS	Hess	75	Good	61	Pass
390	8/31/20	1553.1	52b	MS	Floating Art Sub	54	Fair	61	Fail
840	9/21/17	1553.3	52b	MS	Floating Art Sub	70	Good	61	Pass

Fish:

Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage	Riffle Stream?	FIBI score	FIBI Class	52b FIBI BIT	FIBI Pass/Fail
390	8/31/20	1553	52b	MS	NA	74	Excellent	52	Pass

Overall:

Community	Assessment Type	Assessment Result	Support Level	IR Category	Reason
Benthic Macroinvertebrates	Evaluated	Pass (2/3)	Full
Fish	Evaluated	Pass (1/1)	Full	1	Assessment was evaluated because the drainage areas of the sample sites
Overall	Evaluated	Pass	Full		were greater than the calibrated range.

Class BWW1 - Continuous DO Monitoring:

Site ID	Data Source ID	# Days Monitoring (2020)	DO Criteria Type	# 2020 violations/ Violations needed for impairment	Violates Annual Significantly >10% Rule?	Assessment Type	Support Level
			24 hr	0/4	No
390	6	14	16 hr	0/4	No	Evaluated	Full

Class HH - Fish Tissue Sampling:

Site ID	Biopart	Year	Species	# in sample / # of samples	Avg Length (cm)	(Avg) Hg (ppm)	Chlordane (ppm)	Sum PCBs (ppm)
1124	tissue plug	2012	smallmouth bass	5	34.6	0.467
1124	tissue plug	2011	smallmouth bass	5	41.7	0.376
Support Level	Not	A historic one meal/week mercury consumption advisory existed on this segment. Based on IR Methodology, the Class HH (fish consumption) use was assessed as “not supported.”

Class HH-F - Toxic Parameters:

Site ID	Data Source ID	Parameter Name	# Samples / # Years	Maximum Value	Mean Value	Median Value	Number of Non - Detects	Mean Value > Criterion or MCL	Assessment Type	Support Level
10220001	6	Copper	18 / 2	6.3	1.4	1	8	NO	MONITORED	FULL
Site ID	Data Source ID	Parameter Name	# Samples per Year (2022/ 2023/2024)	2022 Mean	2023 Mean	2024 Mean	# Non-Detects per Year (2022/ 2023/2024)	Support Level per Year (2022/ 2023/2024)	Assessment Type	Support Level
10220001	6	Selenium	12/12/12	0.667	0.542	0.75	8/11/8	FS/FS/FS	MONITORED	FULL

Monitoring and Methods

Assessment Key Dates

8/31/2020

Biological Monitoring

9/22/2011

Fish Tissue Monitoring

8/14/2012

Fish Tissue Monitoring

1/6/2022

Monitoring Start

9/21/2017

Biological Monitoring

10/6/2021

Biological Monitoring

12/3/2024

Monitoring End

Methods

150

Monitoring data more than 5 years old

200

Physical/Chemical Monitoring

260

Fish tissue analysis

315

Regional reference site approach

320

Benthic macroinvertebrate surveys

330

Fish surveys

420

Indicator bacteria monitoring