Now that we've solved the sewer root problem with motor oil, I would like to recommend natural gas for gophers. Simply remove the plug on your meter and screw in a fitting, connect a hose to the fitting and insert the other end of the hose in a fresh gopher hole and wait. It's quiet and requires no traps or making a mess out of your lawn with digging tools.
If you smoke it is not recommend that you light up, especially if you live on the side of a hill and the gophers have been there *a while*.
Gramps Caddy Shack flashback mode.