Thanks for the advice, bumplbea! I'm using Giant Destroyer smoke bombs (I don't think it kills them, but it smells up their tunnels for a long while), and Tomcat poison worms in their tunnels, with some success. Occasionally I can flush them out with the hose, and now that it's cooling off their are coming back to the surface. Haven't seen any evidence of gophers, but you never know for sure. The traps require too much finesse, and I haven't caught one this way.
