2020 Final assessment for Buck Creek

Buck Creek IA 01-MAQ-45

mouth (S11 T87N R4W Delaware Co.) to Golden Branch in S11 T87N R5W Delaware 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: 8/13/2020 12:20:36 PM
Updated: 10/14/2020 6:51:58 AM

Assessment conducted in accordance with Iowa's 2020 IR methodology

Use Support

Class A1

Presumptive Use

Not Assessed

Class BWW2

Partially Supported

Biological: low aquatic macroinvertebrate IBI

Support Level

Partially Supported

Impairment Code

5b-t - Biological - tentative

Cause Magnitude

Slight

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

Low

Cycle Added

2004

Impairment Rationale

Low Biotic Index

Data Source

Biological monitoring: Iowa DNR WQMA

TMDL Priority

Tier IV

Biological: loss of native mussel species

Support Level

Partially Supported

Impairment Code

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

Cause Magnitude

Moderate

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2004

Impairment Rationale

Loss of >50% of native mussel species

Data Source

Special project/study

TMDL Priority

Tier IV

General Use

Not Assessed

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The Class BWW2 use remains assessed as "partially supported" based on information from the report "Statewide Assessment of Freshwater Mussels (Bivalva, Unionidae) in Iowa Streams" by Arbuckle et al. (2000). All other designated uses were "not assessed".

Assessment Explanation

Sources of Data:

Data Source	Data Source ID	Data Type	Data Age	Site ID	Site Name	Site Description
Iowa DNR	6	BIO	See Below	239	Buck Creek	Delhi
Iowa DNR	6	BIO	See Below	1029	Buck Creek	BK001 – 3.5 miles west of Hopkinton
Iowa DNR	6	BIO	See Below	1030	Buck Creek	BK002 – 3 miles west of Hopkinton

Presumptive Class A1 – No Data

Class BWW2 - Biological Sampling:

Benthic Macroinvertebrates:

BioNet Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage	BM Sample Gear	BMIBI score	BMIBI Class	47c BMIBI BIT	BMIBI Pass/ Fail
239	8/16/01	27.6	47c	MS	Hess	54	Fair	70	Fail

Fish:

BioNet Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage	Riffle Stream?	FIBI score	FIBI Class	47c FIBI BIT	FIBI Pass/ Fail
1030	9/17/18	46	47c	MS	Und	62	Good	44	Pass
1029	8/21/17	45	47c	MS	Und	62	Good	44	Pass
1030	8/15/17	46	47c	MS	Und	58	Good	44	Pass
1029	8/2/16	45	47c	MS	Und	51	Good	44	Pass
1030	8/1/16	46	47c	MS	Und	63	Good	44	Pass
1029	8/4/15	45	47c	MS	Und	64	Good	44	Pass
1030	8/3/15	46	47c	MS	Und	64	Good	44	Pass
1030	8/22/14	46	47c	MS	Und	72	Excellent	44	Pass
1029	8/20/14	45	47c	MS	Und	64	Good	44	Pass

Overall Assessment:

Community	Assessment Type	Assessment Result	Support Level	Earned IR Category	Actual IR Category	Reason
Benthic Macroinvertebrates	Evaluated	Fail (0/1)	Partial
Fish	Monitored	Pass (9/9)	Full
Overall	Evaluated	Fail	Partial	3bc	5bt	Assessment is evaluated because the impairment was based on a single BMIBI sample in 2001.

Class BWW2 – Freshwater Mussel Sampling:

Freshwater Mussel Survey	# Freshwater Mussel Species	# Freshwater Mussel Species Increase/Decrease	% Freshwater Mussel Species Increase/Decrease	Assessment Type	Support Level	IR Category
1984-85 (Frest 1987)	6
1998-99 (Arbuckle et al. 2000)	1	-5	-83%	Evaluated	Not	5b
As presented by Arbuckle et al. (2000), the potential causes of declines in species richness of Iowa's freshwater mussels include siltation, destabilization of stream substrate, stream flow instability, and high instream levels of nutrients (phosphorus and nitrogen). Their study also suggested the importance of stream shading provided by riparian vegetation to mussel species richness.

Monitoring and Methods

Assessment Key Dates

9/30/1984	Biological Monitoring
9/30/1999	Biological Monitoring
8/16/2001	Biological Monitoring
8/20/2014	Biological Monitoring
8/22/2014	Biological Monitoring
8/3/2015	Biological Monitoring
8/4/2015	Biological Monitoring
8/1/2016	Biological Monitoring
8/2/2016	Biological Monitoring
8/15/2017	Biological Monitoring
8/21/2017	Biological Monitoring
9/17/2018	Biological Monitoring

Methods

150	Monitoring data more than 5 years old
315	Regional reference site approach
320	Benthic macroinvertebrate surveys
330	Fish surveys

Water Quality Assessments

Impaired Waters List

Buck Creek IA 01-MAQ-45

Assessment Summary

Assessment Explanation

Assessment Key Dates

Methods