West Rat Creek IA 06-BSR-6609

from mouth (T98N R43W Sec22) to headwaters (T99N R42W Sec20 SW SE)

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 8:13:55 AM
Updated: 12/20/2023 2:24:39 PM

Use Support

Class A1

Presumptive Use

Recreation - Primary contact

Not Assessed

Class BWW1

Presumptive Use

Aquatic Life - Warm Water Type 1

Not Supported

Fish Kill: Caused By Pesticides

Support Level

Not Supported

Impairment Code

4d - Pollutant-caused fish kill. No TMDL needed and administrative action taken against responsible party.

Cause Magnitude

Moderate

Status

Continuing

Source

Agriculture

Source Confidence

Moderate

Cycle Added

2016

Impairment Rationale

Pollutant-caused fish kill

Data Source

Fish kill investigation: Iowa DNR

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The presumptive Class BWW1 use remains assessed as "not supported" due to a fish kill investigation. All other designated uses were "not assessed."

Assessment Explanation

Presumptive Class A1 - No Data

Presumptive Class BWW1 - Fish kill Assessment:

The presumptive Class BWW1 aquatic life use assessment based on the 2014 fish kill placed this segment in Category 4d. The fish kill was caused by a “pollutant” or was suspected to be caused by a “pollutant”; therefore, the presumptive Class BWW1 use was considered impaired. However, because restitution for the fish killed was received, the presumptive Class BWW1 use was placed in Category 4d (impaired but TMDL not required). DNR feels that (1) TMDLs should not be required for a fish kill caused by a one-time illegal or unauthorized release of a pollutant where enforcement action was taken and (2) enforcement action is more appropriate and effective for addressing a spill-related impairment than the TMDL process.

Details about the 2014 fish kill can be found here: https://programs.iowadnr.gov/fishkill/Events/878

Monitoring and Methods

Assessment Key Dates

8/20/2014

Fish Kill

Methods

120

Surveys of fish and game biologists/other professionals

140

Incidence of spills and/or fish kills

150

Monitoring data more than 5 years old