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 2016 - 2018
Stream/River Water Quality Data	CY 2016 - 2018
Lake Water Quality Data	CY 2014 - 2018
Biological Sampling Data	CY 2014 - 2018*
Fish Kill Data	CY 2014 - 2018
Fish Tissue Sampling Data	CY 2014 - 2018
Continuous Dissolved Oxygen Sampling Data	CY 2014 - 2018
*Biological sites sampled in both 2013 and 2017 were also assessed.

Open Segment Map
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Cycle: 2020
Release Status: Final
Overall IR: 5 - Water is impaired or threatened and a TMDL is needed.
Trend: Unknown
Created: 9/11/2020 1:28:31 PM
Updated: 10/16/2020 12:07:53 PM

Use Support

Class A1

Presumptive Use

Recreation - Primary contact

Partially Supported

Bacteria: Indicator Bacteria- E. coli

Support Level

Partially 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

WINOFI

Biological: low aquatic macroinvertebrate IBI

Support Level

Further Investigation Needed

Impairment Code

3b-c - Use potentially biologically impaired based on calibrated IBI metrics.

Cause Magnitude

Moderate

Status

New

Source

Unknown: Source Unknown

Source Confidence

Low

Cycle Added

2020

Impairment Rationale

Low Biotic Index

Data Source

Biological monitoring: Iowa DNR WQMA

General Use

General Use water -

Not Assessed

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The presumptive Class A1 use was assessed as "partially supported" due to levels of indicator bacteria (E. coli) that violated state water quality criteria. The Class BWW2 use was assessed as "partially supported” based on biological sampling data.

Assessment Explanation

Sources of Data:

Data Source	Data Source ID	Data Type	Data Age	Site ID	Site Name	Site Description
Iowa DNR	6	WQ	CY 2016-2018	10910003	South River near Ackworth
Iowa DNR	6	BIO	See Below	931	South River	Ackworth

Presumptive Class A1 - Indicator Bacteria:

Site ID	Data Source ID	# Samples / # Years	2016 Geometric Mean	2017 Geometric Mean	2018 Geometric Mean	Annual Geometric Mean Violation	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
10910003	6	16 / 3	858.08	204.25	528.06	Yes	9	56%	Yes	Monitored	Partial

Presumptive Class A1 - pH:

Site ID	Data Source ID	# Samples / # Years	Maximum Value	Mean Value	Median Value	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
10910003	6	36 / 3	8.4	7.8	7.9	0	0%	No	Monitored	Full

Class BWW2 - Conventional Parameters:

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
10910003	6	Ammonia	36 / 3	0.24	0.05	0.02	0 / 0	0% / 0%	No	Monitored	Full
10910003	6	Chloride	36 / 3	32	13	12	0 / 0	0% / 0%	No	Monitored	Full
10910003	6	Dissolved oxygen	36 / 3	16.9	10.3	9.8	NA / 0	NA / 0%	No	Monitored	Full
10910003	6	pH	36 / 3	8.4	7.8	7.9	0 / NA	0% / NA	No	Monitored	Full
10910003	6	Sulfate	36 / 3	53	35.7	38	0 / NA	0% / NA	No	Monitored	Full
10910003	6	Temperature	36 / 3	30.4	12.9	13.5	0 / 0	0% / 0%	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	% Acute/ Chronic Violations	>1 Acute / Chronic Violation	Assessment Type	Support Level
10910003	6	Aluminum	9 / 2	51	8.059	0.45	0 / 0	0% / 0%	No	Evaluated	Full
10910003	6	Arsenic	9 / 2	2	1.1	1	0 / 0	0% / 0%	No	Evaluated	Full
10910003	6	Cadmium	9 / 2	0.07	0.037	0.025	0 / 0	0% / 0%	No	Evaluated	Full
10910003	6	Chromium	9 / 2	0.97	0.63	0.65	0 / 0	0% / 0%	No	Evaluated	Full
10910003	6	Copper	9 / 2	3	1.52	1.3	0 / 0	0% / 0%	No	Evaluated	Full
10910003	6	Lead	9 / 2	0.58	0.147	0.09	0 / 0	0% / 0%	No	Evaluated	Full
10910003	6	Nickel	9 / 2	9.4	4.6	4.4	0 / 0	0% / 0%	No	Evaluated	Full
10910003	6	Selenium	9 / 2	1.7	0.95	0.82	0 / 0	0% / 0%	No	Evaluated	Full
10910003	6	Zinc	9 / 2	3	1.62	1.7	0 / 0	0% / 0%	No	Evaluated	Full

Class BWW2 - Biological Sampling:

Benthic Macroinvertebrates:

BioNet Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage/Thermal	BM Sample Gear	BMIBI score	BMIBI Class	47f BMIBI BIT	BMIBI Pass/ Fail
931	8/2/18	474	47f	MS/WW	Float ArtSub	17	Poor	51	Fail
931	9/23/15	474	47f	MS/WW	Float ArtSub	51	Fair	51	Pass

Overall:

Community	Assessment Type	Assessment Result	Support Level	Earned IR Category	Actual IR Category	Reason
Benthic Macroinvertebrates	Evaluated	Fail (1/2)	Partial	3bc	3bc	Assessment is evaluated because even though both the samples were collected in the last five years, the results were inconclusive.

Monitoring and Methods

Assessment Key Dates

1/11/2016

Fixed Monitoring Start Date

12/4/2018

Fixed Monitoring End Date

9/23/2015

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

420

Indicator bacteria monitoring