Iowa DNR

Water Quality Assessments

Impaired Waters List

Ioway Creek IA 03-SSK-6459

from unnamed tributary (T85N R25W Sec9 NW Boone Co.) to headwaters (T87N R26W Sec34 Hamilton Co.)

Assessment Cycle
Release Status
Data Collection Period
Overall IR Category
4 - Water is impaired or threatened and a TMDL has been completed or is not needed.
10/4/2016 4:06:07 PM
10/4/2016 4:06:07 PM
Assessment conducted in accordance with Iowa's 2016 IR methodology
Use Support
Class A1
Not Assessed
Class BWW1
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
Agriculture: Animal Feeding Operations
Source Confidence
Cycle Added
Impairment Rationale
Pollutant-caused fish kill
Data Source
Fish kill investigation: Iowa DNR
General Use
Not Assessed
Impairment Delistings
No delistings for this assessment cycle.
Assessment Summary

The presumptive Class A1 (primary contact recreation) uses remain "not assessed" (IR 3a) due to lack of information upon which to base an assessment.  The presumptive Class B(WW-1) (aquatic life) uses are assessed (monitored) as "partially supported" (IR 4d) due to the occurrence of a fish kill in August 2011.   

Assessment Explanation

The presumptive Class B(WW-1) (aquatic life) uses are assessed (monitored) as "partially supported" due to the occurrence of a fish kill in August 2011.  The kill occurred on or before August 20, 2011.  Approximately 30,300 fish were killed over 2.75 miles of stream.  The value of the fish was reported as $13,750.22; the cost of the IDNR investigation was $641.56.  The cause of the kill was identified as land-applied animal (swine) manure.   

According to IDNR’s assessment/listing methodology, the occurrence of a single pollutant-caused fish kill, or a fish kill of unknown origin, on a waterbody or waterbody reach during the most recent assessment period indicates a severe stress to the aquatic community and suggests that the aquatic life uses should be assessed as “impaired.” If a cause of the kill is identified, and the cause is either known, or suspected, to be a “pollutant”, the assessment type is considered “monitored” and the affected waterbody is a candidate for Section 303(d) listing.  Fish kills attributed to a pollutant, but where a source of the pollutant was not identified and/or where enforcement actions were not taken against the responsible party, will be placed into Integrated Report subcategory 5b.  The intent of placing these waterbodies into Category 5 is not to necessarily require a TMDL but to keep the impairment highlighted due to the potential for similar future kills from the unaddressed causes and/or sources.  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 will be placed in IR Category 4d (impaired but TMDL not required).  IDNR records show that the party responsible for the kill was identified, and IDNR sought and received restitution for the value of the fish killed and the costs incurred by IDNR during investigation of the kill.  Thus, this assessment segment was placed in Category 4d of Iowa’s 2014 Integrated Report and remains in this IR Category.

Monitoring and Methods
Assessment Key Dates
8/20/2011 Fish Kill
120 Surveys of fish and game biologists/other professionals
140 Incidence of spills and/or fish kills