Iowa DNR 305(b) Water Quality Assessment Database

Iowa DNR Fishkill Database

Casualties of Lotts Creek Fishkill, December 2001 In the past few years, fish kills have become a focus of public attention as more interest is placed on the quality and condition of Iowa's streams and rivers. The Integrated Report, which combines federal requirements for state Section 305(b) water quality assessments and Section 303(d) impaired waters listings, required the Iowa Department of Natural Resources Watershed Monitoring and Assessment Section to begin tracking fishkills. A fishkill can affect the 305(b) water quality assessment of the waterbody and can potentially result in the addition of the water body to the 303(d) list of impaired waters.

The Iowa DNR Fishkill Database stores the data for all fishkills in the state from 1995 to the present. The "Quick Search Links" of the navigation menu to the left allow you to quickly browse all data or narrow your search. The custom search feature allows you to create your own ad-hoc queries.

Fishkill Reporting

If you believe a fishkill has occurred, please immediately contact the nearest Iowa DNR Field Office or Fisheries Office. You should have available the name of the stream, the location of the kill, and any other conditions or observations that may aid in the investigation of the cause and source of the kill. Do note touch the water or remove any dead fish.

Fishkills and Water Quality

As described in Iowa DNR's current methodology for water quality assessments, occurrence of a single pollutant-caused fish kill, or a fish kill of unknown origin, on a waterbody or portion of a waterbody during the most recent three-year period indicates an impairment of the aquatic life uses. This "once in three-year" frequency of criteria violation is designed to provide protection for ecological recovery from a severe stress and is consistent with U.S. EPA recommendations (U.S. EPA 1994: page 3-3).

Each report of a fish kill will be reviewed to determine whether development of a TMDL is appropriate. In the absence of an ongoing source of a pollutant, TMDLs will not be developed for kills caused by a one-time illegal or unauthorized release of manure or other toxic substance. Impacts from this type of fish kill are addressed through IDNR's enforcement procedures. Fish kills attributed to authorized discharges (i.e., a discharge meeting permit limits) are considered for Section 303(d) listing as the existing, required pollution control measures are not adequate to address this impairment.

More information on the role of fish kills in the water quality assessment process can be found at:

From 1999 to 2001, the Iowa Department of Natural Resources (IDNR) and University Hygienic Laboratory (UHL) sampled fish communities in 23 streams that were affected by major fish kills. The primary goal of the project was to assess the status of biological conditions in fish kill streams and evaluate recovery of fish populations. The final report of this project is available in the publications navigation menu to the left.