South River IA 04-LDM-1074

mouth (Warren Co.) to confluence with Squaw Cr. in S2 T75N R24W Warren 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.

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Cycle: 2022
Release Status: Final
Overall IR: 5 - Water is impaired or threatened and a TMDL is needed.
Trend: Unknown
Created: 12/27/2021 10:06:32 AM
Updated: 12/27/2021 10:14:45 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

N/A

Cycle Added

2008

Impairment Rationale

Geometric mean criterion exceeded

Data Source

Ambient monitoring: Iowa DNR-rivers

TMDL Priority

Tier III

Class BWW2

Aquatic Life - Warm Water Type 2

Not Supported

Biological: low aquatic macroinvertebrate IBI

Support Level

Not Supported

Impairment Code

5b-v - Biological - verified

Cause Magnitude

Moderate

Status

New

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2022

Impairment Rationale

Low Biotic Index

Data Source

Biological monitoring: Iowa DNR WQMA

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 violated state water quality criteria. The Class BWW2 use was assessed as "not supported” based on biological sampling 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 2018-2020	10910003	South River near Ackworth
Iowa DNR	6	BIO	See Below	1239	South River	Bank Swallow Bend – Ackworth – REMAP #305
Iowa DNR	6	BIO	See Below	931	South River	Ackworth

Class A1 - Indicator Bacteria:

Site ID

Data Source ID

# Samples per Year (2018/ 2019/2020)

2018 Geometric Mean

2019 Geometric Mean

2020 Geometric Mean

Violates Annual Geometric Mean?

# 2018 SSM violations / SSM Violations needed for impairment

# 2019 SSM violations / SSM Violations needed for impairment

# 2020 SSM violations / SSM Violations needed for impairment

Violates Annual SSM Significantly >10% Rule?

Assessment Type

Support Level

10910003

6/6/8

528

715

365

YES

4 / NA

6 / 3

YES

Monitored

Not

Class A - 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
10910003	6	35 / 3	6.7	8.2	7.8	0	7	NO	Monitored	Full

Class BWW2 - Conventional 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
10910003	6	Ammonia	35 / 3	0.02	0.24	0.05	NA	0 / 0	7	NO	Monitored	Full
10910003	6	Chloride	36 / 3	4.9	32	14.1	NA	0 / 0	7	NO	Monitored	Full
10910003	6	Dissolved Oxygen	36 / 3	5.4	16.9	10.1	0	NA / NA	7	NO	Monitored	Full
10910003	6	pH	35 / 3	6.7	8.2	7.8	0	NA / NA	7	NO	Monitored	Full
10910003	6	Sulfate	36 / 3	9.2	53	35.9	0	NA / NA	7	NO	Monitored	Full
10910003	6	Temperature	36 / 3	0	30.2	12.3	0	NA / NA	7	NO	Monitored	Full

Class BWW2 - 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
10910003	6	Aluminum	14 / 3	51	5.73	0.825	0 / 0	NO	Monitored	Full
10910003	6	Arsenic	13 / 3	2	1.13	1	0 / 0	NO	Monitored	Full
10910003	6	Cadmium	13 / 3	0.07	0.03	0.02	0 / 0	NO	Monitored	Full
10910003	6	Chromium	13 / 3	1	0.6	0.7	0 / 0	NO	Monitored	Full
10910003	6	Lead	13 / 3	0.58	0.16	0.12	0 / 0	NO	Monitored	Full
10910003	6	Nickel	13 / 3	9.4	4.1	3.6	0 / 0	NO	Monitored	Full
10910003	6	Silver	13 / 3	0.025	0.025	0.025	0 / 0	NO	Monitored	Full
10910003	6	Zinc	13 / 3	3	1.88	1.8	0 / 0	NO	Monitored	Full

Class BWW2 - 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
1239	9/23/20	464	47f	MS	Surber	30	Poor	51	Fail
931	8/2/18	474	47f	MS	Floating Art Sub	17	Poor	51	Fail

Fish:

Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage	Riffle Stream?	FIBI score	FIBI Class	47f FIBI BIT	FIBI Pass/ Fail
1239	9/23/20	464	47f	MS	NA	47	Fair	36	Pass

Overall:

Community	Assessment Type	Assessment Result	Support Level	IR Category	Reason
Benthic Macroinvertebrates	Monitored	Fail (0/2)	Not
Fish	Evaluated	Pass (1/1)	Full		Assessment was monitored because the samples used to complete
Overall	Monitored	Fail	Not	5bv	the (BMIBI) assessment were collected in a recent five year period.

Monitoring and Methods

Assessment Key Dates

1/3/2018

Fixed Monitoring Start Date

12/8/2020

Fixed Monitoring End Date

9/23/2020

Biological Monitoring

8/2/2018

Biological Monitoring

Methods

230

Fixed station physical/chemical (conventional plus toxic pollutants)

315

Regional reference site approach

320

Benthic macroinvertebrate surveys

330

Fish surveys

380

Quantitative physical habitat assessment

420

Indicator bacteria monitoring