Big Sioux River IA 06-BSR-1522

from confluence Brule Cr. near Richland SD (S33 T92N R49W Plymouth Co.) to confluence with Indian Cr. in S9 T93N R48W Plymouth 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.

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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: 6/10/2020 1:19:37 PM
Updated: 10/15/2020 11:38:43 AM

Use Support

Class A1

Recreation - Primary contact

Partially Supported

Bacteria: Indicator Bacteria- E. coli

Support Level

Partially Supported

Impairment Code

4a - Pollutant-caused impairment. TMDL has been completed.

Cause Magnitude

Slight

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

Low

Cycle Added

2002

Impairment Rationale

Geometric mean criterion exceeded

Data Source

Ambient monitoring: adjacent state

Class BWW1

Aquatic Life - Warm Water Type 1

Partially Supported

Fish Kill: Caused By Organic Enrichment/Low Dissolved Oxygen

Support Level

Partially Supported

Impairment Code

5b - Biological impairment or pollutant-caused fish kill - unknown source. No administrative action.

Cause Magnitude

Slight

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

Low

Cycle Added

2004

Impairment Rationale

Pollutant-caused fish kill

Data Source

Fish kill investigation: Iowa DNR

TMDL Priority

Tier IV

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

Slight

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

Low

Cycle Added

2008

Impairment Rationale

Low Biotic Index

Data Source

Biological monitoring: Iowa DNR WQMA

Class HH

Human Health -

Fully Supported

General Use

General Use water -

Not Assessed

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The Class A1 use was assessed as "partially supported" due to levels of indicator bacteria (E. coli) that violated state water quality standards. The Class BWW1 use remains assessed as "partially supported" based on a fish kill investigation and on biological sampling data. The Class HH (fish consumption) use remains assessed as "fully supported" based on 2013 fish tissue sampling data.

Assessment Explanation

Note: A TMDL for pathogen indicators in this segment of the Big Sioux River was approved by EPA in 2008. Because all Section 303(d) Class A1 impairments identified for the current IR cycle were addressed by the TMDL, the Class A1 use remains in IR Category 4a.]

Sources of Data:

Data Source	Data Source ID	Data Type	Data Age	Site ID	Site Name	Site Description
SDAK	16	WQ	CY 2016-2018	460832	Big Sioux River
Iowa DNR	6	BIO	See Below	911	Big Sioux River	Akron
Iowa DNR	6	FT	See Below	349	Big Sioux River	At Millsite Access near Westfield

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
460832	16	15 / 3	83.04	107.01	600.19	Yes	6	40%	Yes	Monitored	Partial

Class A - pH:

Site ID	Data Source ID	# Samples / # Years	Maximum Value	Mean Value	Median Value	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
460832	16	36 / 3	9	8.2	8.3	0	0%	No	Monitored	Full

Class BWW1 - 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
460832	16	Ammonia	36 / 3	1.05	0.07	0.02	0 / 0	0% / 0%	No	Monitored	Full
460832	16	Dissolved oxygen	36 / 3	18.1	11	11.1	NA / 0	NA / 0%	No	Monitored	Full
460832	16	pH	36 / 3	9	8.2	8.3	0 / NA	0% / NA	No	Monitored	Full
460832	16	Temperature	36 / 3	27	12	11	0 / 0	0% / 0%	No	Monitored	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	47a BMIBI BIT	BMIBI Pass/ Fail
911	9/5/13	7600	47a	MO/WW	ArtSub	56	Good	54	Pass
911	10/10/12	7600	47a	MO/WW	ArtSub	42	Fair	54	Fail

Overall:

Community	Assessment Type	Assessment Result	Support Level	Earned IR Category	Actual IR Category	Reason
Benthic Macroinvertebrates	Evaluated	Fail (1/2)	Partial	3bu	3bu	Assessment is evaluated because the drainage area of the sample site was larger than the calibrated range.

Class BWW1 – Fish kill Assessment:

The Class BWW1 use assessment based on the 2002 fish kill placed this segment in Category 5b. The fish kill was caused by a “pollutant” or was suspected

to be caused by a “pollutant”; therefore, the Class BWW1 use was considered impaired. Because the source of the pollutant was not identified and/or the

enforcement actions taken against the responsible party have not been resolved, the Class BWW1 use was placed in Category 5b. Due to uncertainty

regarding the recovery of the aquatic life following the fish kill, any existing fish kill 5b impairment will remain in Category 5b until more recent sampling

has shown recovery of the aquatic community or the responsible party has paid restitution.

Details about the 2002 fish kill can be found here:https://programs.iowadnr.gov/fishkill/Events/510

Class HH – Fish Tissue Sampling:

Site ID

Date

Species Name

Biopart

# in sample

chlordane result

chlordane violation (>0.6)?

PCBs result

PCBs violation (>0.2)?

Hg result

Hg violation (>0.3)?

Assessment Type

Support Level

349

9/10/13

channel catfish

fillet

<0.2

<0.6

0.08

Evaluated

Full

Monitoring and Methods

Assessment Key Dates

1/5/2016

Fixed Monitoring Start Date

12/11/2018

Fixed Monitoring End Date

9/10/2013

Fish Tissue Monitoring

1/23/2008

TMDL Completed

10/10/2012

Biological Monitoring

7/12/2002

Fish Kill

9/5/2013

Biological Monitoring

Methods

140

Incidence of spills and/or fish kills

210

Fixed station physical/chemical monitoring (conventional pollutants only)

260

Fish tissue analysis

315

Regional reference site approach

320

Benthic macroinvertebrate surveys

420

Indicator bacteria monitoring