For the first time in a decade, the U.S. EPA will assess the impact of 18 common pesticides on endangered salmon and forest plants, as part of a settlement of a lawsuit filed by three California environmental groups. The pesticides — several million pounds of them — are used every year in the state’s fields, forests, and orchards, and along highways and irrigations canals. The EPA agreed to work with the U.S. Fish and Wildlife Service and the National Marine Fisheries Service to study how exposure to the pesticides carbaryl, chlorpyrifos, and diazinon affects seven salmon species and 33 endangered woodland plants. “These species are close to extinction and pesticides continue to pollute their habitat, but the EPA hasn’t even begun to take action,” said Patty Clary of Californians for Alternatives to Toxics, one of the three groups that sued.