Buttermilk Creek IA 04-UDM-1826

mouth (T92N R26W Sec 33) to headwaters (T92N R26W Sec 34) Wright County

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 2020 - 2022
Stream/River Water Quality Data	CY 2020 - 2022
Lake Water Quality Data	CY 2018 - 2022
Biological Sampling Data	CY 2018 - 2022*
Fish Kill Data	CY 2018 - 2022
Fish Tissue Sampling Data	CY 2018 - 2022
Continuous Dissolved Oxygen Sampling Data	CY 2018 - 2022
*Biological sites sampled in both 2017 and 2021 were also assessed.

Open Segment Map
View assessment methodology in new window

Cycle: 2024
Release Status: Final
Overall IR: 5 - Water is impaired or threatened and a TMDL is needed.
Trend: Unknown
Created: 11/1/2023 8:13:25 AM
Updated: 2/2/2024 8:36:14 AM

Use Support

Class A1

Presumptive Use

Recreation - Primary contact

Not Supported

Bacteria: Indicator Bacteria- E. coli

Support Level

Not 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

2008

Impairment Rationale

Geometric mean criterion exceeded

Data Source

TMDL monitoring: Iowa DNR

TMDL Priority

Tier III

Class BWW1

Presumptive Use

Aquatic Life - Warm Water Type 1

WINOFI

Biological: low fish & invert IBIs- cause unknown

Support Level

Further Investigation Needed

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

2006

Impairment Rationale

Low Biotic Index

Data Source

Biological monitoring: Iowa DNR WQMA

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The presumptive Class A1 use was assessed as “not supported” due to levels of indicator bacteria (E. coli) that exceeded state water quality criteria. The presumptive Class BWW1 use was assessed (evaluated) as “WINOFI” based on biological sampling data.

Assessment Explanation

Data Sources:

Data Source	Data Source ID	Data Type	Data Age	Site ID	Site Name	Site Description
Iowa DNR	6	WQ	CY 2006-2007	11990001	Buttermilk Creek	BMC1
Iowa DNR	6	WQ	CY 2006-2007	11990003	Buttermilk Creek	BMC3
Iowa DNR	6	BIO	See Below	545	Buttermilk Creek	BMC1
Iowa DNR	6	BIO	See Below	546	Buttermilk Creek	BMC2
Iowa DNR	6	BIO	See Below	547	Buttermilk Creek	BMC3

Presumptive Class A1 - Indicator Bacteria:

Site ID	Data Source ID	# Samples / # Years	2006-2007 Geometric Mean	Annual Geometric Mean Violation	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
11990001	6	13 / 2	294	Yes	9	69%	Yes	Evaluated	Not
11990003	6	10 / 2	161	Yes	6	60%	Yes	Evaluated	Not

Presumptive Class BWW1 - Biological Sampling:

Benthic Macroinvertebrates:

BioNet Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage/Thermal	BM Sample Gear	BMIBI score	BMIBI Class	47b BMIBI BIT	BMIBI Pass/Fail
547	9/4/07	4	47b	MS/WW	ArtSub	38	Fair	62	Fail
546	9/6/06	4	47b	MS/WW	ArtSub	20	Poor	62	Fail
547	9/6/06	4	47b	MS/WW	ArtSub	14	Poor	62	Fail
545	9/5/06	4	47b	MS/WW	ArtSub	23	Poor	62	Fail

Fish:

BioNet Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage/Thermal	Riffle Stream?	FIBI score	FIBI Class	47b FIBI BIT	FIBI Pass/Fail
546	9/5/07	4	47b	MS/WW	Yes	39	Fair	53	Fail
547	9/4/07	4	47b	MS/WW	Yes	44	Fair	53	Fail
545	9/4/07	4	47b	MS/WW	No	55	Good	32	Pass
545	9/5/06	4	47b	MS/WW	No	42	Fair	32	Pass

Overall:

Community	Assessment Type	Assessment Result	Support Level	IR Category	Reason
Benthic Macroinvertebrates	Evaluated	Fail (0/4)	WINOFI
Fish	Evaluated	Fail (2/4)	WINOFI
Overall	Evaluated	Fail	WINOFI	3bu	Assessment was evaluated because the drainage areas of the sample sites were smaller than the calibrated range.

Monitoring and Methods

Assessment Key Dates

9/4/2007

Biological Monitoring

9/5/2007

Biological Monitoring

9/5/2006

Biological Monitoring

9/6/2006

Biological Monitoring

6/26/2006

Monitoring Start

4/17/2007

Monitoring End

Methods

150

Monitoring data more than 5 years old

315

Regional reference site approach

320

Benthic macroinvertebrate surveys

330

Fish surveys

420

Indicator bacteria monitoring