Iowa DNR
Iowa DNR
ADBNet
Water Quality Assessments
Impaired Waters List

Unnamed Tributary to West Fork Cedar River IA 02-WFC-1919

mouth (NW1/4 NE1/4 S29 T93N R19W Franklin Co.) to headwaters in NE1/4 S18 T93N R20W Franklin Co.

Cycle
2018
Release Status
Final
Overall IR
3 - Insufficient data exist to determine whether any designated uses are met.
Trend
Unknown
Created
7/29/2019 9:22:23 AM
Updated
7/29/2019 9:23:28 AM
Use Support
Class A1
Recreation - Primary contact
Not Assessed
Class BWW1
Aquatic Life - Warm Water Type 1
WINOFI
Impairment Code
3b - Use potentially impaired based on an evaluated assessment.
Cause Magnitude
Moderate
Status
Continuing
Source
Agriculture
Source Confidence
High
Cycle Added
2006
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 remain "not assessed" due to the lack of information upon which to base an assessment.  The presumptive Class B(WW1) aquatic life uses of this stream are assessed as “partially supported” due to a fish kill in June 2005.

Assessment Explanation

This kill occurred north of Chapin, IA, on or before June 18, 2005, and was attributed to fertilizer. A tank of anhydrous ammonia fertilizer being pulled by a tractor spilled. Despite attempts to control the discharge of the fertilizer, most of the 850 gallons of fertilizer vented to the atmosphere. The hovering of the vapor cloud near the ground, and the dissolving of the ammonia into the water of the unnamed tributary, is believed to be the cause of the kill. An estimated 2,072 non-game fish were killed (minnows, stonerollers, and darters). The estimated value of the fish killed was $201. Approximately 5.25 miles of stream were affected by the kill.

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, this assessment segment was placed in Category 4d of Iowa’s 2006 through 2010 Integrated Reports. DNR considers IR 4d fish kill waters with no subsequent kills in at least the five years subsequent to the kill as appropriate for movement to IR categories 2b or 3b (i.e., Iowa’s list of waters in need of further investigation). Thus, this fish kill impairment was moved from Category 4d to Category 3b of Iowa’s 2012 Integrated Report and will be included on Iowa’s list of waters in need of further investigation.

Monitoring and Methods
Assessment Key Dates
6/18/2005
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