Willow Creek IA 06-LSR-1626

mouth (S17 T94N R36W Clay Co.) to confluence with unnamed tributary in NW 1/4 S31 T95N R37W Clay 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: 12/30/2021 2:03:51 PM
Updated: 1/31/2022 1:06:58 PM

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

Moderate

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

Low

Cycle Added

2012

Impairment Rationale

Geometric mean criterion exceeded

Data Source

TMDL monitoring: Iowa DNR

TMDL Priority

Tier III

Class BWW2

Aquatic Life - Warm Water Type 2

Not Supported

Biological: low aquatic macroinvertebrate IBI

Support Level

Not Supported

Impairment Code

5b-t - Biological - tentative

Cause Magnitude

Moderate

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

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The presumptive Class A1 use was assessed as "not supported" due to violations of the state water quality criteria for indicator bacteria. The Class BWW2 use was assessed as “not supported” based on biological sampling data. All other designated uses were "not assessed."

Assessment Explanation

Data Sources:

Data Source	Data Source ID	Data Type	Data Age	Site ID	Site Name	Site Description
Iowa DNR	6	WQ	CY 2010-2011	11210003	Willow Creek near Royal
Iowa DNR	6	BIO	See Below	205	Willow Creek	Royal
Iowa DNR	6	BIO	See Below	306	Willow Creek	Rossie – REMAP #31

Presumptive Class A1 - Indicator Bacteria:

Site ID	Data Source ID	# Samples / # Years	2010 Geometric Mean	Annual Geometric Mean Violation	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
11210003	6	12 / 1	1113	Yes	10	77%	Yes	Evaluated	Not

Class BWW2 - 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
11210003	6	Ammonia	37 / 2	0.46	0.06	0.05	0 / 0	0% / 0%	No	Evaluated	Full
11210003	6	Chloride	12 / 2	24	19	20	0 / 0	0% / 0%	No	Evaluated	Full
11210003	6	Dissolved oxygen	19 / 2	12.5	9.2	9.6	NA / 0	NA / 0%	No	Evaluated	Full
11210003	6	pH	19 / 2	8.5	7.9	7.9	0 / NA	0% / NA	No	Evaluated	Full
11210003	6	Sulfate	12 / 2	64	46	47	0 / NA	0% / NA	No	Evaluated	Full
11210003	6	Temperature	19 / 2	26.3	15.8	17.6	0 / 0	0% / 0%	No	Evaluated	Full

Presumptive Class BWW1 - Biological Sampling:

Benthic Macroinvertebrates:

BioNet Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage	BM Sample Gear	BMIBI score	BMIBI Class	47a BMIBI BIT	BMIBI Pass/Fail
306	8/1/18	51	47a	MO	Hess	22	Poor	54	Fail
205	9/19/11	50	47a	MO	Surber	51	Fair	54	Fail

Fish:

BioNet Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage	Riffle Stream?	FIBI score	FIBI Class	47a FIBI BIT	FIBI Pass/Fail
306	8/1/18	51	47a	MO	NA	41	Fair	43	Fail
205	9/19/11	50	47a	MO	NA	54	Good	43	Pass
205	9/14/09	50	47a	MO	NA	52	Good	43	Pass

Overall:

Community	Assessment Type	Assessment Result	Support Level	IR Category	Reason
Benthic Macroinvertebrates	Evaluated	Fail (0/2)	Not
Fish	Evaluated	Pass (2/3)	Full
Overall	Evaluated	Fail	Not	5bt	Assessment was evaluated because it included samples not collected in the last five years.

Class BWW2 - Continuous DO Monitoring: 2018

Site ID	Data Source ID	# Days Monitoring (2016/2017/2018/ 2019/2020)	DO Criteria Type	# 2016 violations / Violations needed for impairment	# 2017 violations / Violations needed for impairment	# 2018 violations / Violations needed for impairment	# 2019 violations / Violations needed for impairment	# 2020 violations / Violations needed for impairment	Violates Annual Significantly >10% Rule?	Assessment Type	Support Level
			24 hr	NA	NA	0/4	NA	NA	No
306	6	0/0/14/0/0	16 hr	NA	NA	0/4	NA	NA	No	Evaluated	Full

Monitoring and Methods

Assessment Key Dates

3/9/2010

Non-fixed Monitoring Start Date

11/1/2011

Non-fixed Monitoring End Date

9/14/2009

Biological Monitoring

9/19/2011

Biological Monitoring

8/1/2018

Biological Monitoring

Methods

150

Monitoring data more than 5 years old

222

Non-fixed-station monitoring (conventional during key seasons and flows)

315

Regional reference site approach

320

Benthic macroinvertebrate surveys

330

Fish surveys

380

Quantitative physical habitat assessment

420

Indicator bacteria monitoring