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 2014 - 2016
Stream/River Water Quality Data	CY 2014 - 2016
Lake Water Quality Data	CY 2012 - 2016
Biological Sampling Data	CY 2012 - 2016*
Fish Kill Data	CY 2012 - 2016
Fish Tissue Sampling Data	CY 2012 - 2016
Continuous Dissolved Oxygen Sampling Data	CY 2012 - 2016
*Biological sites sampled in both 2011 and 2015 were also assessed.

Open Segment Map
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Cycle: 2018
Release Status: Final
Overall IR: 4 - Water is impaired or threatened and a TMDL has been completed or is not needed.
Trend: Unknown
Created: 8/5/2019 11:53:01 AM
Updated: 8/5/2019 11:59:27 AM

Use Support

Class A1

Presumptive Use

Recreation - Primary contact

Not Assessed

Class BWW2

Aquatic Life - Warm Water Type 2

Partially Supported

Fish Kill: Caused By Animal Waste

Support Level

Partially Supported

Impairment Code

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

Cause Magnitude

High

Status

New

Source

Agriculture: Animal Feeding Operations

Source Confidence

High

Cycle Added

2018

Impairment Rationale

Pollutant-caused fish kill

Data Source

Fish kill investigation: Iowa DNR

General Use

General Use water -

Not Assessed

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The presumptive Class A1 (primary contact recreation) uses are “not assessed” due to the lack of information upon which to base an assessment. The Class B(WW2) aquatic life uses are assessed as “partially supporting” based on 2013 fish kill.

Assessment Explanation

The fish kill occurred on or before August 17, 2013 and was attributed to runoff from a cattle facility on a unnamed tributary of West Branch Mill Creek. Approximately 865,940 dead fish were found up to 27.9 miles downstream of the tributary. The estimated value of the dead fish was $158,551.63 and the investigation expenses were $1,945.73. The party responsible for the kill was identified and restitution was sought and received.

According to DNR's assessment methodology for Section 305(b) reporting, occurrence of a single pollution-caused fish kill during an assessment period indicates "partial support" of the aquatic life uses. If, however, a consent order has been issued to the party responsible for the kill and monetary restitution has been sought for the fish killed, the affected waterbody should be placed in IR Category 4d (impaired but TMDL not required). Thus, based on the 2013 fish kill and due to the receipt of restitution of the value of the fish killed and the cost of the DNR fish kill investigation, the aquatic life uses of this stream will are assessed as impaired (partially supporting) and placed in Category 4d of Iowa’s Integrated Report.

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