Willow Creek IA 02-WIN-848

mouth (SW 1/4 S32 T98N R21W Worth Co.) to headwaters (Worth 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 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
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Cycle: 2024
Release Status: Final
Overall IR: 2 - Some of the designated uses are met but there is insufficient data to determine if remaining designated uses are met.
Trend: Unknown
Created: 11/1/2023 8:12:35 AM
Updated: 12/15/2023 1:13:28 PM

Use Support

Class A1

Presumptive Use

Recreation - Primary contact

Not Assessed

Class BWW1

Presumptive Use

Aquatic Life - Warm Water Type 1

Fully Supported

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The presumptive Class BWW1 use was assessed as "fully 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	BIO	See Below	31	Willow Creek	Willow Creek Wildlife Area - Hanlontown

Presumptive Class A1 – No Data

Presumptive Class BWW1 - Biological Sampling:

Benthic Macroinvertebrates:

Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage	BM Sample Gear	BMIBI score	BMIBI Class	47b BMIBI BIT	BMIBI Pass/Fail
31	7/20/22	20.5	47b	MS	Surber	65	Good	62	Pass
31	8/4/21	20.5	47b	MS	Surber	54	Fair	62	Fail
31	7/15/20	20.5	47b	MS	Hess	71	Good	62	Pass
31	7/22/19	20.5	47b	MS	Hess	68	Good	62	Pass
31	8/7/18	20.5	47b	MS	Hess	50	Fair	62	Fail

Fish:

Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage	Riffle Stream?	FIBI score	FIBI Class	47b FIBI BIT	FIBI Pass/Fail
31	7/20/22	20.5	47b	MS	Yes	45	Fair	53	Fail
31	8/4/21	20.5	47b	MS	Yes	58	Good	53	Pass
31	7/15/20	20.5	47b	MS	Yes	59	Good	53	Pass
31	7/22/19	20.5	47b	MS	Yes	67	Good	53	Pass
31	8/7/18	20.5	47b	MS	Yes	64	Good	53	Pass

Overall:

Community	Assessment Type	Assessment Result	Support Level	IR Category	Reason
Benthic Macroinvertebrates	Evaluated	Pass (3/5)	Full
Fish	Evaluated	Pass (4/5)	Full		Assessment was evaluated because the drainage area of the site
Overall	Evaluated	Pass	Full	1	used for the assessment was smaller than the calibrated range.

Monitoring and Methods

Assessment Key Dates

8/4/2021

Biological Monitoring

8/7/2018

Biological Monitoring

7/20/2022

Biological Monitoring

7/22/2019

Biological Monitoring

7/15/2020

Biological Monitoring

Methods

315

Regional reference site approach

320

Benthic macroinvertebrate surveys

330

Fish surveys