2020 assessment for Volga River

Volga River IA 01-VOL-290

from confluence with Cox Cr. (S21 T92N R5W Clayton Co.) to bridge crossing in Volga (north line S10 T92N R6W Clayton Co.).

2020
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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Overall IR

4 - Water is impaired or threatened and a TMDL has been completed or is not needed.

Trend

Unknown

Created

10/2/2020 7:44:53 AM by

Updated

10/15/2020 11:54:24 AM by

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

303(d) Listing Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2002

Impairment Rationale

Geometric mean criterion exceeded

Data Source

TMDL monitoring: Iowa DNR

Class BWW1

Aquatic Life - Warm Water Type 1

Not Assessed

Class HH

Human Health -

Not Assessed

General Use

General Use water -

Not Assessed

303(d) Delistings for this Cycle

No delistings for this assessment cycle.

Documentation

Assessment Summary

The Class A1 use remains assessed as "not supported" based on levels of indicator bacteria (E. coli) that violated state water quality standards. All other designated uses were “not assessed." Note: A TMDL for pathogen indicators in this segment of the Volga River was prepared by DNR and approved by EPA in 2006. Because the primary Section 303(d) impairment identified for the current assessment/listing cycle (indicator bacteria) is addressed by the TMDL, this waterbody was moved from IR Category 5a from the 2004 assessment/listing cycle to IR Category 4a (impaired; TMDL approved) for the 2006 cycle; this waterbody remains in IR Category 4a.

Assessment Explanation

Sources of Data:

Data Source	Data Source ID	Data Type	Data Age	Site ID	BioNet Site ID	Site Name	Site Description
Iowa DNR	6	WQ	CY 2001	11220004		Volga River E of Volga, Osborne Park (34)
Iowa DNR	6	WQ	CY 2001	11220007		Volga River at Volga (35)

Presumptive Class A1 - Indicator Bacteria: Historical

Site ID	Data Source ID	# Samples / # Years	2001 Geometric Mean	Annual Geometric Mean Violation	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
11220004	6	9 / 1	245	Yes	4	44%	NA	Evaluated	Partial
11220007	6	9 / 1	276	Yes	4	44%	NA	Evaluated	Partial

Class BWW1 - No Data

Class HH - No Data

Monitoring and Methods

Assessment Key Dates

3/27/2001

Fixed Monitoring Start Date

11/13/2001

Fixed Monitoring End Date

11/9/2006

TMDL Completed

Methods

150

Monitoring data more than 5 years old

220

Non-fixed station physical/chemical monitoring (conventional pollutant only)

420

Indicator bacteria monitoring