Environmental groups and a commercial fishers group in the Northwest sued the U.S. EPA yesterday to protect salmon from small amounts of pesticides often found in rivers. The plaintiffs want the agency to review how pesticides might be harming the fish and to place tougher restrictions on pesticide use until the review is complete. Studies by the U.S. Geological Survey have detected low levels of pesticides in many of the region’s rivers, and the National Marine Fisheries Service recently found that minute amounts of common pesticides can disturb the nervous system of salmon, jeopardizing their survival.