Brush Creek IA 01-VOL-317

mouth (S26 T93N R7W Fayette Co.) to confluence with Bear Cr. in S8 T92N R7W Fayette Co.

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 2018 - 2020
Stream/River Water Quality Data	CY 2018 - 2020
Lake Water Quality Data	CY 2016 - 2020
Biological Sampling Data	CY 2016 - 2020*
Fish Kill Data	CY 2016 - 2020
Fish Tissue Sampling Data	CY 2016 - 2020
Continuous Dissolved Oxygen Sampling Data	CY 2016 - 2020
*Biological sites sampled in both 2015 and 2019 were also assessed.

Open Segment Map
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Cycle: 2022
Release Status: Final
Overall IR: 5 - Water is impaired or threatened and a TMDL is needed.
Trend: Unknown
Created: 12/17/2021 6:54:35 AM
Updated: 12/17/2021 6:56:30 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

Moderate

Cycle Added

2016

Impairment Rationale

Geometric mean criterion exceeded

Data Source

Watershed project monitoring

TMDL Priority

Tier III

Class BWW2

Aquatic Life - Warm Water Type 2

Fully Supported

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 slightly exceeded state water quality criteria. The Class BWW2 use was assessed as "fully supported" based on water quality monitoring data and 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 2012-2014	15330002	Brush Creek at Bush Road/C24	BRU10
Iowa DNR	6	BIO	See Below	165	Brush Creek	Wadena

Presumptive Class A1 – Indicator Bacteria: 2012-2014

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
15330002	6	24 / 3	113	211	38	Yes	4	17%	No	Evaluated	Not

Presumptive Class A1 - pH: 2012-2014

Site ID	Data Source ID	# Samples / # Years	Maximum Value	Mean Value	Median Value	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
15330002	6	24 / 3	8.8	8.3	8.31	0	0%	No	Evaluated	Full

Class BWW2 - Conventional Parameters: 2012-2014

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
15330002	6	Ammonia	16 / 2	0.12	0.06	0.05	0 / 0	0% / 0%	No	Evaluated	Full
15330002	6	Chloride	16 / 2	33	31	31	0 / 0	0% / 0%	No	Evaluated	Full
15330002	6	Dissolved oxygen	24 / 3	12	8.4	8	NA / 0	NA / 0%	No	Evaluated	Full
15330002	6	pH	24 / 3	8.8	8.3	8.31	0 / NA	0% / NA	No	Evaluated	Full
15330002	6	Temperature	24 / 3	24	14.4	14.4	0 / 0	0% / 0%	No	Evaluated	Full

Class BWW2 - Biological Sampling:

Benthic Macroinvertebrates:

Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage	BM Sample Gear	BMIBI score	BMIBI Class	52b BMIBI BIT	BMIBI Pass/Fail
165	9/2/20	31.7	52b	MS	Hess	75	Good	61	Pass
165	9/24/16	31.7	52b	MS	Hess	82	Excellent	61	Pass

Fish:

Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage	Riffle Stream?	FIBI score	FIBI Class	52b FIBI BIT	FIBI Pass/Fail
165	9/2/20	31.7	52b	MS	NA	78	Excellent	52	Pass
165	9/24/16	31.7	52b	MS	NA	83	Excellent	52	Pass

Overall:

Community	Assessment Type	Assessment Result	Support Level	IR Category	Reason
Benthic Macroinvertebrates	Monitored	Pass (2/2)	Full
Fish	Monitored	Pass (2/2)	Full	1	Assessment was monitored because the assessment used multiple
Overall	Monitored	Pass	Full		samples collected in a recent five year period to complete the assessment.

Monitoring and Methods

Assessment Key Dates

4/4/2012

Non-fixed Monitoring Start Date

11/5/2014

Non-fixed Monitoring End Date

9/2/2020

Biological Monitoring

8/25/2016

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

380

Quantitative physical habitat assessment

420

Indicator bacteria monitoring