It’s the first step in what could be a long crackdown on pesticide use in the Pacific Northwest.
The Environmental Protection Agency is placing new limits on the use of three organophosphate pesticides – chlorpyrifos, diazinon and malathion. The rules apply to Oregon, Washington, Idaho and California.

A Chinook salmon. Courtesy NOAA.
The EPA is trying to keep these chemical out of streams and rivers that are home to salmon and steelhead. Research shows that these pesticides can interfere with a salmon’s ability to smell, making it harder for the fish to hunt prey. The chemicals may also kill prey and reduce the salmon’s food supply. In high enough concentrations, the pesticides can outright kill salmon.
How do the new rules work? First, they require buffer zones around salmon and steelhead habitat. These are areas where the pesticides can’t be used. The size of the buffer zone will depend on weather conditions, and how the pesticides will be applied. The idea is to keep the pesticides from drifting into fish waters.
Other restrictions including no spraying on windy and rainy days, or when rain is in the forecast, to prevent the chemicals from running off fields and into streams.
For the most part, these rules follow recommendations by NOAA Fisheries. The EPA is asking manufacturers to voluntarily adopt these limits, with the threat of taking regulatory action if they don’t.
But what’s especially important about today’s announcement is that it may be the first in a very long series of new rulings on pesticide use. The EPA and NOAA will spend the next couple of years studying three dozen pesticides in the Northwest. So far, six of them have been labeled as threats to salmon and steelhead. That includes the three pesticides mentioned above.


