Gopher traps. But the ones that kill quick, some are horribly slow and should really not be used.
I delayed doing that for years because I hate killing mammals, but the naturally occuring predators don't manage to keep the populations down in bad years. Killing a few early in the season seems to be the best compromise.
Edit: Also poison should be avoided at all costs, it's poisoning the predators, which is very undesirable and will make the problem worse.