Mill Creek IA 06-LSR-1617

from confluence with Whiskey Cr. (east line S29 T94N R41W O'Brien Co.) to confluence with West Branch Mill Cr. in S4 T95N R41W O'Brien 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: 3 - Insufficient data exist to determine whether any designated uses are met.
Trend: Unknown
Created: 1/10/2022 10:08:51 AM
Updated: 1/14/2022 12:30:19 PM

Use Support

Class A1

Presumptive Use

Recreation - Primary contact

Not Assessed

Class BWW2

Aquatic Life - Warm Water Type 2

WINOFI

Fish Kill: Caused By Animal Waste

Support Level

Further Investigation Needed

Impairment Code

3b - Use potentially impaired based on an evaluated assessment.

Cause Magnitude

High

Status

Continuing

Source

Agriculture: Animal Feeding Operations

Source Confidence

High

Cycle Added

2018

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 Class BWW2 use was assessed as "WINOFI" due to a fish kill investigation. All other designated uses were "not assessed."

Assessment Explanation

Presumptive Class A1 - No Data

The Class BWW2 aquatic life use previously resided in Category 4d based on the assessment developed for the 2013 fish kill. Because no additional fish kills were reported in this segment for at least five years post fish kill (2018), the Category for the fish kill assessment was changed from 4d to 3b (potentially impaired). DNR believes that any impact from the fish kill from which the impairment was based has likely dissipated. If no additional fish kills are reported in the segment for an additional five-year period (2023), the Category will be changed from 3b to 3a (water not assessed).

Details about the 2013 fish kill can be found here: https://programs.iowadnr.gov/fishkill/Events/876

Monitoring and Methods

Assessment Key Dates

8/17/2013

Fish Kill

Methods

120

Surveys of fish and game biologists/other professionals

140

Incidence of spills and/or fish kills