Walnut Creek IA 04-LDM-1069

mouth (S24 T77N R21W Marion Co.) to headwaters in NE1/4 SE30 T79N R21W Jasper 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: 2 - Some of the designated uses are met but there is insufficient data to determine if remaining designated uses are met.
Trend: Unknown
Created: 12/28/2021 10:02:31 AM
Updated: 2/3/2022 1:37:06 PM

Use Support

Class A1

Presumptive Use

Recreation - Primary contact

Fully Supported

Class BWW1

Presumptive Use

Aquatic Life - Warm Water Type 1

WINOFI

Biological: low fish IBI

Support Level

Further Investigation Needed

Impairment Code

3b-u - Use potentially biologically impaired based on uncalibrated IBI metrics.

Cause Magnitude

Slight

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

Low

Cycle Added

2006

Impairment Rationale

Low Biotic Index

Data Source

Special project/study

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The presumptive Class A1 use was assessed as "fully supported" based on water quality monitoring data. The presumptive Class BWW1 use was assessed 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
USGS	11	WQ	CY 2013	5487550	Walnut Creek	Near Vandalia, IA
Iowa DNR	6	BIO	See Below	219	Walnut Creek	Neal Smith Wildlife Refuge – Combined WNT2 & WNTBM2

Presumptive Class A1 - pH:

Site ID	Data Source ID	# Samples / # Years	Maximum Value	Mean Value	Median Value	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
5487550	11	15 / 1	8.1	7.8	7.8	0	0%	No	Evaluated	Full

Presumptive Class BWW1 - 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
5487550	11	Ammonia	15 / 1	0.07	0.03	0.03	0 / 0	0% / 0%	No	Evaluated	Full
5487550	11	Chloride	12 / 1	14.6	13	12.8	0 / 0	0% / 0%	No	Evaluated	Full
5487550	11	Dissolved oxygen	15 / 1	10.6	9	9.4	NA / 0	NA / 0%	No	Evaluated	Full
5487550	11	pH	15 / 1	8.1	7.8	7.8	0 / NA	0% / NA	No	Evaluated	Full
5487550	11	Sulfate	12 / 1	23.9	17.5	15.9	0 / NA	0% / NA	No	Evaluated	Full
5487550	11	Temperature	15 / 1	24.1	17.8	17.2	0 / 0	0% / 0%	No	Evaluated	Full

Presumptive Class BWW1 - Biological Sampling:

Fish:

BioNet Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage/Thermal	Riffle Stream?	FIBI score	FIBI Class	47f FIBI BIT	FIBI Pass/ Fail
219	9/19/05	20	47f	MS/WW	NA	29	Fair	36	Fail
219	9/21/04	20	47f	MS/WW	NA	22	Poor	36	Fail

Overall:

Community	Assessment Type	Assessment Result	Support Level	IR Category	Reason
Fish	Evaluated	Fail (0/2)	WINOFI	3bu	Assessment was evaluated because it included samples not collected in the last five years and the drainage area of the site was smaller than the calibrated range.

Monitoring and Methods

Assessment Key Dates

9/21/2004

Biological Monitoring

9/19/2005

Biological Monitoring

5/9/2013

Fixed Monitoring Start Date

9/17/2013

Fixed Monitoring End Date

Methods

150

Monitoring data more than 5 years old

220

Non-fixed station physical/chemical monitoring (conventional pollutant only)

315

Regional reference site approach

330

Fish surveys