2024 Pending assessment for Chariton River

Chariton River IA 05-CHA-1308

from the Highway 2 crossing (S27 T69N R17W Appanoose Co.) to Rathbun Dam in S35 T69N R18W Appanoose Co.

Assessment Cycle

2024

Release Status

Pending

Data Collection Period

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.

Overall IR Category: 5 - Water is impaired or threatened and a TMDL is needed.
Trend: Stable

Created: 11/1/2023 8:13:00 AM
Updated: 1/18/2024 10:06:37 AM

Assessment conducted in accordance with Iowa's 2024 IR methodology.

Use Support

Class A1

Not Supported

Bacteria: Indicator Bacteria- E. coli

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

2008

Impairment Rationale

Geometric mean criterion exceeded

Data Source

Ambient monitoring: Iowa DNR-rivers

TMDL Priority

Tier III

Class BWW1

WINOFI

Fish Kill: Due To Natural Causes

Support Level

Water in Need of Further Investigation (WINOFI)

Impairment Code

3b - Use potentially impaired based on an evaluated assessment.

Cause Magnitude

Slight

Status

Continuing

Source

Hydromodification: Dam Release

Source Confidence

N/A

Cycle Added

2020

Impairment Rationale

Non Pollutant-caused fish kill

Data Source

Fish kill investigation: Iowa DNR

Class C

Fully Supported

Class HH

Fully Supported

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The 2020-2022 E. coli data suggest full support of the Class A1 use; however, delisting an impairment requires a monitored assessment. Therefore, the Category 5a Class A1 impairment will remain. The Class BWW1 use was assessed as "WINOFI" due to a fish kill investigation. The Class C use was assessed as "fully supported" based on water quality monitoring data and drinking water compliance monitoring required by the DNR. The Class HH use was assessed as "fully supported" based on fish tissue sampling 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 2020-2022	10040002	Chariton River at 461st St.
USACE	12	WQ	CY 2020-2022	99990007	Rathbun Reservoir Outlet (Site RA-28)
Iowa DNR	6	BIO	See Below	420	Chariton River	Rathbun (REMAP #101)
Iowa DNR	6	BIO	See Below	914	Chariton River	Rathbun at 461st St. Bridge
Iowa DNR	6	FT	See Below	1146	Chariton River	N of Centerville

Class A1 - Indicator Bacteria:

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

10040002

8/8/8

1 / 3

2 / 3

Eval

Full

The 2020-2022 E. coli data suggest full support of the Class A1 use; however, delisting an impairment requires a monitored assessment. Therefore, the Category 5a Class A1 impairment will remain.

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
10040002	6	35 / 3	6.3	8.4	7.7	1	7	NO	Mon	Full
99990007	12	6 / 1	7.48	8.15	7.86	0	3	NO	Eval	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
10040002	6	Chloride	36 / 3	6	28	10	NA	0 / 0	7	NO	Mon	Full
10040002	6	Dissolved Oxygen	36 / 3	5.5	14	9.7	0	NA / NA	7	NO	Mon	Full
99990007	12	Dissolved Oxygen	15 / 3	0.25	11.86	7.47	2	NA / NA	4	NO	Mon	Full
10040002	6	pH	35 / 3	6.3	8.4	7.7	1	NA / NA	7	NO	Mon	Full
99990007	12	pH	6 / 1	7.48	8.15	7.86	0	NA / NA	3	NO	Eval	Full
10040002	6	Sulfate	36 / 3	13	26	19	0	NA / NA	7	NO	Mon	Full
10040002	6	Temperature	36 / 3	0	26.5	12.5	0	NA / NA	7	NO	Mon	Full
99990007	12	Temperature	15 / 3	8.7	26.2	20.9	0	NA / NA	4	NO	Mon	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
10040002	6	Ammonia	35 / 3	0.28	0.07	0.05	0 / 0	NO	Mon	Full
99990007	12	Ammonia	6 / 1	0.2	0.2	0.2	0 / 0	NO	Eval	Full
10040002	6	Cadmium	20 / 3	0.5	0.5	0.5	0 / 0	NO	Mon	Full
10040002	6	Chromium	20 / 3	2	0.49	0.25	0 / 0	NO	Mon	Full
10040002	6	Lead	20 / 3	1	0.9	1	0 / 0	NO	Mon	Full
10040002	6	Nickel	20 / 3	2.7	1.8	1.7	0 / 0	NO	Mon	Full
10040002	6	Selenium	18 / 2	0.5	0.5	0.5	0 / 0	NO	Mon	Full
10040002	6	Silver	20 / 3	1	0.902	1	0 / 0	NO	Mon	Full
10040002	6	Zinc	20 / 3	2.2	0.6	0.5	0 / 0	NO	Mon	Full

Class BWW1 - Biological Sampling:

Benthic Macroinvertebrates:

BioNet Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage/Thermal	BM Sample Gear	BMIBI score	BMIBI Class	40a BMIBI BIT	BMIBI Pass/Fail
914	8/3/22	550.0	40a	MS/WW	Hess	55	Fair	41	Pass
420	9/15/21	555.4	40a	MS/WW	Floating ArtSub	36	Fair	41	Fail
914	7/20/18	550.0	40a	MS/WW	Hess	63	Good	41	Pass

Fish:

BioNet Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage/Thermal	Riffle Stream?	FIBI score	FIBI Class	40a FIBI BIT	FIBI Pass/Fail
420	9/15/21	555.4	40a	MS/WW	NA	35	Fair	33	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		Assessment was evaluated because the drainage area of the sites
Overall	Evaluated	Pass	Full	1	used for the assessment were greater than the calibrated range.

Class BWW1- Continuous DO Monitoring:

Site ID	Data Source ID	# Days Monitoring (2021)	DO Criteria Type	# 2021 violations / Violations needed for impairment	Violates Annual Significantly >10% Rule?	Assessment Type	Support Level
			24 hr	0/5	No
420	6	21	16 hr	0/5	No	Evaluated	Full

Class BWW1 – Fish kill Assessment:

The Class BWW1 aquatic life use assessment based on the 2018 fish kill placed this segment in Category 3b. Because the cause of the fish kill was not identified, or the fish kill was attributed to a non-pollutant cause (e.g., winterkill), the assessment type is “evaluated.” Segments assessed using “evaluated” assessments are placed in Category 3b and are added to the state list of waters in need of further investigation (WINOFI). If no additional fish kills are reported in the segment for a 10 year period (2028), the Category will be changed from 3b to 3a (not assessed).

Details about the 2018 fish kill can be found here: https://programs.iowadnr.gov/fishkill/Events/952

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
10040002	6	Chloride	36 / 3	6	28	10	10	0	NO	Mon	Full
10040002	6	Inorganic nitrogen (nitrate and nitrite)	36 / 3	0.16	0.82	0.42	0.38	0	NO	Mon	Full
99990007	12	Inorganic nitrogen (nitrate and nitrite)	16 / 3	0.003	0.806	0.319	0.204	0	NO	Mon	Full
10040002	6	pH	35 / 3	6.3	8.4	7.7	7.7	1	NO	Mon	Full
99990007	12	pH	6 / 1	7.48	8.15	7.86	7.94	0	NO	Eval	Full

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 finished water caused by source water at the Rathbun Regional Water Assn facility during the 2020-22 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 - Fish Tissue Sampling:

Site ID	Biopart	Year	Species	# in sample / # of samples	Avg. Length (cm)	(Avg.) Hg (ppm)	Chlordane (ppm)	Sum PCBs (ppm)
1146	tissue plug	2013	white crappie	5	20.9	0.195
Support Level	Full

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
10040002	6	Selenium	18 / 2	0.5	0.5	0.5	18	NO	Mon	Full

Monitoring and Methods

Assessment Key Dates

1/6/2020	Monitoring Start
12/1/2022	Monitoring End
7/31/2013	Fish Tissue Monitoring
8/3/2022	Biological Monitoring
3/4/2018	Fish Kill
7/20/2018	Biological Monitoring
9/15/2021	Biological Monitoring
9/15/2021	Monitoring Start
10/5/2021	Monitoring End

Methods

140	Incidence of spills and/or fish kills
200	Physical/Chemical Monitoring
260	Fish tissue analysis
275	Drinking water compliance reports
315	Regional reference site approach
320	Benthic macroinvertebrate surveys
330	Fish surveys
420	Indicator bacteria monitoring

Water Quality Assessments

Impaired Waters List

Chariton River IA 05-CHA-1308

Assessment Summary

Assessment Explanation

Assessment Key Dates

Methods