Nodaway River (aka West Nodaway R.) IA 05-NOD-1389

from confluence with East Nodaway R. (S6 T67N R36W Page Co.) to confluence with Middle Nodaway R. in S33 T71N R36W Montgomery 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 3:09:47 PM
Updated: 2/11/2026 10:16:50 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

Moderate

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

Low

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

WINOFI

Biological: low aquatic macroinvertebrate IBI

Support Level

Further Investigation Needed

Impairment Code

3b-u - Use potentially biologically impaired based on uncalibrated IBI metrics.

Cause Magnitude

Moderate

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

Low

Cycle Added

2008

Impairment Rationale

Potential Impairment

Data Source

Biological monitoring: Iowa DNR WQMA

Class C

Drinking Water -

Fully Supported

Class HH

Human Health -

Fully Supported

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 violated water quality criteria. The Class BWW1 use was assessed as "WINOFI" based on biological sampling data. The Class C use as assessed as “fully supported” based on water quality monitoring data and drinking water compliance monitoring required by the DNR. The Class HH use as 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 2014-2016, 2022-2024	10730001	West Nodaway River at Shambaugh
USGS	11	WQ	CY 2024-2024	99990198	Nodaway River at Clarinda, IA
IA PWS	27	WQ	CY 2022-2024	99990206	Nodaway River
Iowa DNR	6	BIO	See Below	936	West Nodaway River	Shambaugh

Presumptive Class A1 - Indicator Bacteria: 2014-2016

Site ID	Data Source ID	# Samples / # Years	2014 Geo. Mean	2015 Geo. Mean	2016 Geo. Mean	Annual Geometric Mean Violation	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
10730001	6	24 / 3	1505	911	1133	Yes	21	88%	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
10730001	6	36 / 3	7.5	8.5	8.1	0	7	NO	MONITORED	FULL
99990198	11	5 / 1	7.5	8.4	8.1	0	2	NO	EVALUATED	FULL
99990206	27	731 / 2	7.7	9.3	8.5	3	85	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
10730001	6	Chloride	36 / 3	12	19	15	NA	0 / 0	7	NO	MONITORED	FULL
10730001	6	Dissolved Oxygen	36 / 3	7.7	14.9	10.8	0	NA / NA	7	NO	MONITORED	FULL
99990198	11	Dissolved Oxygen	5 / 1	8.4	12	9.6	0	NA / NA	2	NO	EVALUATED	FULL
10730001	6	pH	36 / 3	7.5	8.5	8.1	0	NA / NA	7	NO	MONITORED	FULL
99990198	11	pH	5 / 1	7.5	8.4	8.1	0	NA / NA	2	NO	EVALUATED	FULL
99990206	27	pH	731 / 2	7.7	9.3	8.5	3	NA / NA	85	NO	MONITORED	FULL
10730001	6	Sulfate	36 / 3	12	33	23	0	NA / NA	7	NO	MONITORED	FULL
10730001	6	Temperature	36 / 3	0	27.8	13.5	0	NA / NA	7	NO	MONITORED	FULL
99990198	11	Temperature	5 / 1	0.8	26.3	18.2	0	NA / NA	2	NO	EVALUATED	FULL
99990206	27	Temperature	730 / 2	4	28	16	0	NA / NA	84	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
10730001	6	Ammonia	36 / 3	1.1	0.1	0.02	0 / 0	NO	MONITORED	FULL
10730001	6	Cadmium	17 / 2	0.5	0.5	0.5	0 / 0	NO	MONITORED	FULL
10730001	6	Chromium	17 / 2	12	1.57	0.52	0 / 1	NO	MONITORED	FULL
10730001	6	Copper	18 / 2	5.5	2.2	1.9	0 / 0	NO	MONITORED	FULL
10730001	6	Lead	17 / 2	1	1	1	0 / 0	NO	MONITORED	FULL
10730001	6	Nickel	17 / 2	4.8	1.7	1.4	0 / 0	NO	MONITORED	FULL
10730001	6	Selenium	36 / 3	3	1	1	0 / 0	NO	MONITORED	FULL
10730001	6	Silver	17 / 2	1	1	1	0 / 0	NO	MONITORED	FULL
10730001	6	Zinc	17 / 2	2.3	1	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	47f BMIBI BIT	BMIBI Pass/Fail
936	8/6/24	777	47f	MO	Floating Art Sub	48	Fair	54	Fail
936	8/12/20	777	47f	MO	Floating Art Sub	38	Fair	54	Fail

Overall:

Community	Assessment Type	Assessment Result	Support Level	IR Category	Reason
Benthic Macroinvertebrates	Evaluated	Fail (0/2)	WINOFI		Assessment was evaluated because the drainage area of the sample site
Overall	Evaluated	Fail	WINOFI	3bu	was larger than the calibrated range.

Class C - Binomial Parameters:

Site ID	Data Source ID	Parameter Name	# Samples / # Years	Minimum Value	Maximum Value	Mean Value	Median Value	# Violations	Violates Significantly >10% Rule?	Assessment Type	Support Level
10730001	6	Chloride	36 / 3	12	19	15	15	0	NO	MONITORED	FULL
99990206	27	Fluoride	36 / 3	70	470	288	305	0	NO	MONITORED	FULL
10730001	6	Inorganic nitrogen (nitrate and nitrite)	36 / 3	0.05	7.8	2.2	1.8	0	NO	MONITORED	FULL
99990198	11	Nitrate	5 / 1	0.5	8.1	3.4	2.1	0	NO	EVALUATED	FULL
10730001	6	pH	36 / 3	7.5	8.5	8.1	8.1	0	NO	MONITORED	FULL
99990198	11	pH	5 / 1	7.5	8.4	8.1	8.2	0	NO	EVALUATED	FULL
99990206	27	pH	731 / 2	7.7	9.3	8.5	8.5	3	NO	MONITORED	FULL

Class C - Toxic Parameters: No Data

Class C - Iowa Drinking Water Compliance Report:

Compliance monitoring required by the Iowa DNR Water Supply Operations and Engineering Sections did not show violations of finished water caused by source water at the Clarinda Water Plant facility during the 2022-24 monitoring period. The results of compliance monitoring as reported in annual compliance reports are available at the following location at the Iowa DNR’s home page:https://www.iowadnr.gov/Environmental-Protection/Water-Quality/Water-Supply-Engineering/Annual-Compliance-Report.

Class HH-FW - 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
10730001	6	Copper	18 / 2	5.5	2.2	1.9	1	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
10730001	6	Selenium	12/12/12	1	1.033	1.008	6/4/5	FS/FS/FS	MONITORED	FULL

Monitoring and Methods

Assessment Key Dates

1/7/2014

Monitoring Start

12/6/2016

Monitoring End

8/6/2024

Biological Monitoring

1/5/2022

Monitoring Start

12/31/2024

Monitoring End

8/12/2020

Biological Monitoring

Methods

150

Monitoring data more than 5 years old

200

Physical/Chemical Monitoring

275

Drinking water compliance reports

315

Regional reference site approach

320

Benthic macroinvertebrate surveys

420

Indicator bacteria monitoring