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Release of Atrazine Ecological Watershed Monitoring Data

Atrazine Ecological Watershed Monitoring Program

In its determination that products containing atrazine were eligible for reregistration, EPA required the atrazine registrants to undertake an intensive watershed monitoring program to further confirm that use of this herbicide was not likely to cause unreasonable risk to freshwater resources.  After discussions with the Agency, one of the registrants (Syngenta) developed an ecological watershed monitoring program and a mitigation process to implement if atrazine water concentrations exceed a level at which aquatic community effects could occur.  This program is detailed in the October 2003 Revised Atrazine IRED (PDF) (12 pp, 108 KB, about PDF).

One component of the monitoring program is focused on flowing water bodies associated with corn and sorghum production.  This monitoring program started in 2004, and the last data were collected in fall 2006.  Once EPA reviews and assesses the data, this statistically based monitoring study will permit EPA to make inferences from the 40 indicator watersheds as to the condition of a larger population of 1,172 vulnerable watersheds.  The effects of a chemical on aquatic community structure are highly dependent on duration and frequency, as well as magnitude of exposure.  During 2007, EPA is analyzing the data collected and will discuss the monitoring program and results of our analysis with the FIFRA Scientific Advisory Panel (SAP) later in the year.

Atrazine registrants have monitored streams in 40 indicator watersheds, each for a period of two years, to determine whether atrazine levels of concern were exceeded.  Watersheds exceeding these levels are subject to watershed management program remedies required under FIFRA conditions of registration.  When such a watershed management program is required, it will be prepared and implemented in a manner similar to the EPA Office of Water’s Total Maximum Daily Load (TMDL) program requirements and to the extent possible will be integrated with any existing watershed management programs. Currently, two such programs have begun based on monitoring results in the South Fabius River Watershed and Youngs Creek Watershed in Missouri (sites MO 01 and MO 02). 

Why EPA is Releasing Data Now

Consistent with a March 2006 Settlement Agreement between EPA and the Natural Resources Defense Council (NRDC), EPA is assessing the potential effects of atrazine use to eight threatened and endangered species.  That assessment is scheduled to be completed by February 28, 2007. 

The Settlement Agreement also states that 30 days before completing the effects determination, EPA must provide NRDC and the public access to the atrazine ecological water monitoring data that have been submitted to the Agency to date and that are relevant to the upcoming effects determinations.  The Agency has determined that all data submitted to date under this monitoring program are relevant to the assessments being conducted, and therefore is making the full set of data available.

How to Obtain Data under FIFRA Section 10(g)

To obtain these ecological water monitoring data you must complete and sign an Affirmation of Non-multinational Status Form pursuant to FIFRA section 10(g).  This provision protects U.S. pesticide registrants against unauthorized use of their health and safety data by competitors to obtain pesticide registrations in foreign countries.  The affirmation form and more information are available on EPA’s Freedom of Information Web site.  The form includes directions for returning the required information to EPA.  When requesting these data, you should request the “Atrazine Ecological Watershed Monitoring Data”.   EPA will provide these data in pdf format or in hard copy if you do not have pdf capability.


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