2020 Final assessment for Volga River

Volga River IA 01-VOL-296

confluence with Little Volga R. (S2 T92N R9W Fayette Co.) to confluence with unnamed tributary in SE 1/4 S24 T93N R10W Fayette Co.

Assessment Cycle

2020

Release Status

Final

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 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.

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

Created: 8/25/2020 6:53:23 AM
Updated: 10/14/2020 10:56:16 AM

Assessment conducted in accordance with Iowa's 2020 IR methodology

Use Support

Class A1

Presumptive Use

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

Slight

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2014

Impairment Rationale

Geometric mean criterion exceeded

Data Source

Watershed project monitoring

TMDL Priority

Tier III

Class BWW2

Fully Supported

General Use

Not Assessed

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The presumptive Class A1 use remains assessed as “partially supported” due to violations of Iowa water quality criteria for indicator bacteria (E. coli). The Class BWW2 use was assessed as “fully supported” based on biological sampling data and water quality monitoring data. This segment is not designated for the Class HH use in the Iowa Surface Water Classification Document. However, a one meal/week consumption advisory for mercury exists on this segment of the Volga River – see https://www.iowadnr.gov/Environmental-Protection/Water-Quality/Water-Monitoring/Fish-Tissue

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 2012-2014	15330013	Volga River at Q Ave	VR40
Iowa DNR	6	BIO	See Below	39	Volga River	Maynard – Twin Bridges County Park
Iowa DNR	6	BIO	See Below	265	Volga River	Randalia (VO003)
Iowa DNR	6	BIO	See Below	1024	Volga River	US Twin Bridges Park (VO002)

Presumptive Class A1 - Indicator Bacteria:

Site ID	Data Source ID	# Samples / # Years	2012 Geometric Mean	2013 Geometric Mean	2014 Geometric Mean	Annual Geometric Mean Violation	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
15450013	6	24 / 3	259	701	239	Yes	16	67%	Yes	Evaluated	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
15330013	6	21 / 3	9.1	8.15	8.1	4	4%	No	Evaluated	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
15330013	6	Ammonia	8 / 1	0.13	0.08	0.05	0 / 0	0% / 0%	No	Evaluated	Full
15330013	6	Chloride	18 / 3	33	31	30	NA / 0	NA / 0%	No	Evaluated	Full
15330013	6	Dissolved Oxygen	24 / 3	10	8	8	0 / NA	0% / NA	No	Evaluated	Full
15330013	6	pH	21 / 3	9.1	8.15	8.1	1 / 0	4% / 0%	No	Evaluated	Full
15330013	6	Temperature	23 / 3	28.2	14.5	14.2	NA / 0	NA / 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	47c BMIBI BIT	BMIBI Pass/ Fail
39	7/30/18	54	47c	MS/WW	Hess	76	Excellent	70	Pass
265	7/30/18	22	47c	MS/WW	Hess	76	Excellent	70	Pass
265	10/9/13	22	47c	MS/WW	Surb	56	Good	70	Fail
39	10/8/13	54	47c	MS/WW	Surb	66	Good	70	Fail
265	8/31/10	22	47c	MS/WW	Hess	58	Good	70	Fail
39	8/30/10	54	47c	MS/WW	Hess	70	Good	70	Pass
39	9/18/01	54	47c	MS/WW	Hess	73	Good	70	Pass
265	9/17/01	22	47c	MS/WW	Surb	80	Excellent	70	Pass

Fish:

BioNet Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage/ Thermal	Riffle Stream?	FIBI score	FIBI Class	47c FIBI BIT	FIBI Pass/ Fail
1024	8/29/18	56	47c	MS/WW	Und	76	Excellent	44	Pass
265	8/22/18	22	47c	MS/WW	Yes	72	Excellent	65	Pass
39	7/31/18	54	47c	MS/WW	Yes	76	Excellent	65	Pass
265	7/30/18	22	47c	MS/WW	Yes	81	Excellent	65	Pass
1024	8/28/17	56	47c	MS/WW	Und	74	Excellent	44	Pass
265	8/24/17	22	47c	MS/WW	Yes	74	Excellent	65	Pass
1024	8/31/16	56	47c	MS/WW	Und	71	Excellent	44	Pass
265	8/29/16	22	47c	MS/WW	Yes	74	Excellent	65	Pass
1024	8/19/15	56	47c	MS/WW	Und	76	Excellent	44	Pass
265	8/11/15	22	47c	MS/WW	Yes	74	Excellent	65	Pass
1024	8/19/14	56	47c	MS/WW	Und	79	Excellent	44	Pass
265	8/13/14	22	47c	MS/WW	Yes	78	Excellent	65	Pass

Overall:

Community	Assessment Type	Assessment Result	Support Level	Earned IR Category	Actual IR Category	Reason
Benthic Macroinvertebrates	Evaluated	Pass (5/8)	Full
Fish	Monitored	Pass (12/12)	Full
Overall	Evaluated	Pass	Full	1	1	Assessment is evaluated because samples used to complete the assessment were greater than five years old.

Monitoring and Methods

Assessment Key Dates

4/4/2012	Fixed Monitoring Start Date
11/5/2014	Fixed Monitoring End Date
10/8/2013	Biological Monitoring
10/9/2013	Biological Monitoring
8/13/2014	Biological Monitoring
8/19/2014	Biological Monitoring
8/19/2015	Biological Monitoring
8/31/2016	Biological Monitoring
8/29/2016	Biological Monitoring
8/30/2010	Biological Monitoring
8/31/2010	Biological Monitoring
9/18/2001	Biological Monitoring
9/17/2001	Biological Monitoring
8/11/2015	Biological Monitoring
8/24/2017	Biological Monitoring
8/28/2017	Biological Monitoring
7/30/2018	Biological Monitoring
7/31/2018	Biological Monitoring
8/22/2018	Biological Monitoring
8/29/2018	Biological Monitoring

Methods

150	Monitoring data more than 5 years old
220	Non-fixed station physical/chemical monitoring (conventional pollutant only)
315	Regional reference site approach
320	Benthic macroinvertebrate surveys
330	Fish surveys
420	Indicator bacteria monitoring

Water Quality Assessments

Impaired Waters List

Volga River IA 01-VOL-296

Assessment Summary

Assessment Explanation

Assessment Key Dates

Methods