South Fork Chariton River IA 05-CHA-1328

from confluence with Ninemile Cr. (S4 T69N R22W Wayne Co.) to outfall of Bob White Lake in S4 T68N R22W Wayne 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 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.

Open Segment Map
View assessment methodology in new window

Cycle: 2024
Release Status: Final
Overall IR: 5 - Water is impaired or threatened and a TMDL is needed.
Trend: Improving
Trend Comment: Monitoring from 2000-2002 showed impairments related to low levels of dissolved oxygen. Levels of dissolved oxygen appear to have improved over the last 12 years of monitoring.
Created: 11/1/2023 8:13:10 AM
Updated: 2/6/2024 7:52:40 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: Corps of Engineers/Iowa DNR/ISU

TMDL Priority

Tier III

Class BWW2

Aquatic Life - Warm Water Type 2

Not Supported

Biological: low fish & invert IBIs- cause unknown

Support Level

Not Supported

Impairment Code

5b-t - Biological - tentative

Cause Magnitude

Moderate

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

Low

Cycle Added

2006

Impairment Rationale

Low Biotic Index

Data Source

Biological monitoring: Iowa DNR WQMA

TMDL Priority

Tier IV

Organic Enrichment: Low Dissolved Oxygen

Support Level

Further Investigation Needed

Impairment Code

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

Cause Magnitude

Slight

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2022

Impairment Rationale

Potential Impairment

Data Source

Ambient monitoring: Iowa DNR-continuous

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 BWW2 use was assessed as “not supported” based on biological sampling data and assessed as "WINOFI" based on continuous dissolved oxygen monitoring data.

Assessment Explanation

Data Sources:

Data Source	Data Source ID	Data Type	Data Age	Site ID	Site Name	Site Description
USACE	12	WQ	CY 2010-2014	15930002	South Fork Chariton River (Site RA-35)
Iowa DNR	6	WQ	CY 2016	12930003	South Fork Chariton River near Corydon
Iowa DNR	6	BIO/WQ	See Below	906	South Fork Chariton River	Corydon

Presumptive Class A1 - Indicator Bacteria: 2010-2012

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
15930002	12	15 / 3	679	489	208	Yes	10	67%	Yes	Evaluated	Not

Presumptive Class A1 - pH: 2012-2014

Site ID	Data Source ID	# Samples / # Years	Maximum Value	Mean Value	Median Value	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
15930002	12	38 / 3	8	7.6	7.6	0	0%	No	Evaluated	Full

Presumptive Class A1 - pH: 2016

Site ID	Data Source ID	# Samples / # Years	Maximum Value	Mean Value	Median Value	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
12930003	6	5 / 1	8	7.9	7.9	0	0%	No	Evaluated	Full

Class BWW2 - Binomial Parameters: 2012-2014

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
15930002	12	Ammonia	24 / 3	0.78	0.1	0.05	0 / 0	0% / 0%	No	Evaluated	Full
15930002	12	Chloride	17 / 3	17	8.4	7.3	0 / 0	0% / 0%	No	Evaluated	Full
15930002	12	Dissolved oxygen	38 / 3	12.2	8.4	8	NA / 0	NA / 0%	No	Evaluated	Full
15930002	12	pH	38 / 3	8	7.6	7.6	0 / NA	0% / NA	No	Evaluated	Full
15930002	12	Temperature	38 / 3	25.3	17	18.3	0 / 0	0% / 0%	No	Evaluated	Full

Class BWW2 - Binomial Parameters: 2016

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
12930003	6	Ammonia	6 / 1	0.07	0.06	0.05	0 / 0	0% / 0%	No	Evaluated	Full
12930003	6	Chloride	6 / 1	31	16	13	0 / 0	0% / 0%	No	Evaluated	Full
12930003	6	Dissolved oxygen	6 / 1	6.5	6	6	NA / 0	NA / 0%	No	Evaluated	Full
12930003	6	pH	5 / 1	8	7.9	7.9	0 / NA	0% / NA	No	Evaluated	Full
12930003	6	Sulfate	6 / 1	30	24	24	0 / 0	0% / 0%	No	Evaluated	Full
12930003	6	Temperature	6 / 1	24.3	22.8	23	0 / 0	0% / 0%	No	Evaluated	Full

Class BWW2 - Biological Sampling:

Benthic Macroinvertebrates:

BioNet Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage	BM Sample Gear	BMIBI score	BMIBI Class	40a BMIBI BIT	BMIBI Pass/Fail
906	9/6/16	37	40a	MO	Surb	41	Fair	41	Pass
906	8/8/16	37	40a	MO	Surb	51	Fair	41	Pass
906	9/12/12	37	40a	MO	ArtSub	20	Poor	41	Fail

Fish:

BioNet Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage	Riffle Stream?	FIBI score	FIBI Class	40a FIBI BIT	FIBI Pass/Fail
906	8/8/16	37	40a	MO	NA	35	Fair	33	Pass
906	9/12/12	37	40a	MO	NA	28	Fair	33	Fail

Overall:

Community	Assessment Type	Assessment Result	Support Level	IR Category	Reason
Benthic Macroinvertebrates	Evaluated	Pass (2/3)	Full
Fish	Evaluated	Fail (1/2)	Not
Overall	Evaluated	Fail	Not	5bt	Assessment was evaluated because it included samples not collected in the last five years.

Class BWW2- Continuous DO Monitoring:

Site ID	Data Source ID	# Days Monitoring (2016)	DO Criteria Type	# 2016 violations/Violations needed for impairment	Violates Annual Significantly >10% Rule?	Assessment Type	Support Level
			24 hr	17/12	Yes
906	6	72	16 hr	9/12	No	Evaluated	WINOFI

Monitoring and Methods

Assessment Key Dates

3/14/2012

Monitoring Start

10/21/2014

Monitoring End

9/12/2012

Biological Monitoring

8/8/2016

Biological Monitoring

9/6/2016

Biological Monitoring

9/10/2012

Monitoring End

3/6/2010

Monitoring Start

7/12/2016

Monitoring Start

9/21/2016

Monitoring End

Methods

150

Monitoring data more than 5 years old

200

Physical/Chemical Monitoring

315

Regional reference site approach

320

Benthic macroinvertebrate surveys

330

Fish surveys

420

Indicator bacteria monitoring