Bennett Creek IA 02-IOW-6263

From confluence with unnamed tributary (T83N R15W Sec31 Tama County) to headwaters (T82N R16W Sec16 Tama 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
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Cycle: 2024
Release Status: Final
Overall IR: 4 - Water is impaired or threatened and a TMDL has been completed or is not needed.
Trend: Unknown
Created: 11/1/2023 8:14:12 AM
Updated: 4/19/2024 10:44:10 AM

Use Support

Class A2

Recreation - Secondary contact

Not Supported

Bacteria: Indicator Bacteria- E. coli

Support Level

Not Supported

Impairment Code

4a - Pollutant-caused impairment. TMDL has been completed.

Cause Magnitude

Moderate

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2010

Impairment Rationale

Potential Impairment

Data Source

Ambient monitoring: USGS

Class BWW2

Aquatic Life - Warm Water Type 2

Fully Supported

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The Class A2 use was assessed (evaluated) as "not supported" based on levels of indicator bacteria (E. coli) that exceeded state water quality criteria. The Class BWW2 was assessed as "fully supported" based on water quality monitoring data. Note: A TMDL covering the bacteria impairments for all segments, with the segment code prefix "IA 02-IOW" in the Iowa River Basin, was approved by EPA in 2018.

Assessment Explanation

Data Sources:

Data Source	Data Source ID	Data Type	Data Age	Site ID	Site Name	Site Description
MESK	25	WQ	CY 2020-2021	99990098	Bennett Creek

Class A2 - Indicator Bacteria:

Site ID	Data Source ID	# Samples per Year (2020/2021)	2020 Geometric Mean	2021 Geometric Mean	Violates Annual Geometric Mean?	# 2020 SSM violations / SSM Violations needed for impairment	# 2021 SSM violations / SSM Violations needed for impairment	Violates Annual SSM Significantly >10% Rule?	Assessment Type	Support Level
99990098	25	5/6	1293	1107	YES	0 / NA	0 / NA	NA	Eval	Not

Class A2 - pH:

Site ID	Data Source ID	# Samples / # Years	Minimum Value	Maximum Value	Mean Value	# Violations	Violations needed for impairment	Violates Significantly >10% Rule?	Assessment Type	Support Level
99990098	25	10 / 2	7.58	8.43	8.04	0	3	NO	Mon	Full

Class BWW2 - Binomial Parameters:

Site ID	Data Source ID	Parameter Name	# Samples / # Years	Minimum Value	Maximum Value	Mean Value	# Violations	# Acute / Chronic Violations	Violations needed for impairment	Violates Significantly >10% Rule?	Assessment Type	Support Level
99990098	25	Dissolved Oxygen	10 / 2	7.37	13.13	9.92	0	NA / NA	3	NO	Mon	Full
99990098	25	pH	10 / 2	7.58	8.43	8.04	0	NA / NA	3	NO	Mon	Full
99990098	25	Temperature	10 / 2	5.1	27.7	15.8	0	NA / NA	3	NO	Mon	Full

Monitoring and Methods

Assessment Key Dates

4/21/2020

Monitoring Start

10/27/2021

Monitoring End

3/9/2018

TMDL Completed

Methods

200

Physical/Chemical Monitoring

420

Indicator bacteria monitoring