Boyer River IA 06-BOY-1502

from confluence with Willow Cr. (S28 T78N R44W Harrison Co.) to the Harrison-Crawford county line.

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: Stable

Created: 9/18/2020 12:03:00 PM
Updated: 10/13/2020 2:26:49 PM

Assessment conducted in accordance with Iowa's 2020 IR methodology

Use Support

Class A1

Recreation

Primary contact

Not Supported

Impairments

Support Level

Not Supported

Impairment Code

5a - Pollutant-caused impairment. TMDL needed.

Cause Magnitude

Moderate

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

Low

Cycle Added

2008

Impairment Rationale

Geometric mean criterion exceeded

Data Source

Ambient monitoring: Iowa DNR-rivers

TMDL Priority

Tier III

Class BWW1

Aquatic Life

Warm Water Type 1

Not Supported

Impairments

Support Level

Not Supported

Impairment Code

5a - Pollutant-caused impairment. TMDL needed.

Cause Magnitude

Moderate

Status

New

Source

Unknown: Source Unknown

Source Confidence

Low

Cycle Added

2020

Impairment Rationale

Violations of chronic criterion

Data Source

Ambient monitoring: Iowa DNR-rivers

TMDL Priority

Tier IV

Further Investigation Needed

Support Level

Water in Need of Further Investigation (WINOFI)

Impairment Code

3b-u - Use potentially biologically impaired based on uncalibrated IBI metrics.

Cause Magnitude

Moderate

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

Low

Cycle Added

2014

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 remains assessed as "not supported" due to levels of indicator bacteria (E. coli) that violated state water quality criteria. The Class BWW1 use was assessed as "not supported" based on water quality monitoring data (violations of the chronic selenium criteria) and "partially supported" based on biological sampling data. The Class HH use was assessed as "fully supported" based on water quality monitoring 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 2014-2016, CY 2016-2018	10430001	Boyer River near Missouri Valley
Iowa DNR	6	BIO	See Below	912	Boyer River	Missouri Valley

Class A1 - Indicator Bacteria:

Site ID	Data Source ID	# Samples / # Years	2014 Geometric Mean	2015 Geometric Mean	2016 Geometric Mean	Annual Geometric Mean Violation	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
10430001	6	24 / 3	487	1138	539	Yes	18	75%	Yes	Evaluated	Not

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
10430001	6	35 / 3	8.5	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
10430001	6	Ammonia	35 / 3	0.69	0.06	0.02	0 / 0	0% / 0%	No	Monitored	Full
10430001	6	Chloride	36 / 3	110	20	17	0 / 0	0% / 0%	No	Monitored	Full
10430001	6	Dissolved oxygen	36 / 3	14.3	10.1	10	NA / 0	NA / 0%	No	Monitored	Full
10430001	6	pH	35 / 3	8.5	8.2	8.3	0 / NA	0% / NA	No	Monitored	Full
10430001	6	Sulfate	36 / 3	50	35	35	0 / NA	0% / NA	No	Monitored	Full
10430001	6	Temperature	36 / 3	25.2	12.2	11.5	0 / 0	0% / 0%	No	Monitored	Full

Class BWW1 - 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
10430001	6	Aluminum	9 / 2	16	4.86	3.8	0 / 0	0% / 0%	No	Evaluated	Full
10430001	6	Arsenic	9 / 2	4.4	2.9	2.5	0 / 0	0% / 0%	No	Evaluated	Full
10430001	6	Cadmium	9 / 2	0.05	0.028	0.025	0 / 0	0% / 0%	No	Evaluated	Full
10430001	6	Chromium	9 / 2	1.4	0.95	1	0 / 0	0% / 0%	No	Evaluated	Full
10430001	6	Copper	9 / 2	2.3	1.22	1.1	0 / 0	0% / 0%	No	Evaluated	Full
10430001	6	Lead	9 / 2	0.23	0.081	0.07	0 / 0	0% / 0%	No	Evaluated	Full
10430001	6	Nickel	9 / 2	5	3	2.7	0 / 0	0% / 0%	No	Evaluated	Full
10430001	6	Selenium	9 / 2	11	6.6	6.1	0 / 8	0% / 89%	Yes	Evaluated	Not
10430001	6	Zinc	9 / 2	9.6	2.05	0.71	0 / 0	0% / 0%	No	Evaluated	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	47m BMIBI BIT	BMIBI Pass/ Fail
912	8/13/18	928	47m	MO/WW	Float ArtSub	56	Good	54	Pass
912	9/24/14	928	47m	MO/WW	Float ArtSub	49	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 HH-F - Toxic Parameters:

Site ID	Data Source ID	Parameter Name	# Samples / # Years	Maximum Value	Mean Value	Median Value	Number of Non - Detects	Mean Value > Criterion or MCL	Assessment Type	Support Level
10430001	6	Cadmium	9 / 2	0.05	0.028	0.025	8	No	Evaluated	Full
10430001	6	Chromium	9 / 2	1.4	0.95	1	0	No	Evaluated	Full
10430001	6	Copper	9 / 2	2.3	1.22	1.1	0	No	Evaluated	Full
10430001	6	Nickel	9 / 2	5	3	2.7	0	No	Evaluated	Full
10430001	6	Selenium	9 / 2	11	6.6	6.1	0	No	Evaluated	Full
10430001	6	Zinc	9 / 2	9.6	2.05	0.71	0	No	Evaluated	Full

Monitoring and Methods

Assessment Key Dates

1/5/2016

Fixed Monitoring Start Date

12/5/2018

Fixed Monitoring End Date

8/13/2018

Biological Monitoring

9/24/2014

Biological Monitoring

1/7/2014

Fixed Monitoring Start Date

12/7/2016

Fixed Monitoring End Date

Methods

230

Fixed station physical/chemical (conventional plus toxic pollutants)

315

Regional reference site approach

320

Benthic macroinvertebrate surveys

420

Indicator bacteria monitoring