Gophers can be a nuisance for gardens, lawns and trees. They can Kill trees within days, and ruin a garden in no time. Killing them can be as easy as pie.
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Step 1: Anatomy of a Gopher Burrow

This is a gopher burrow. It consists of a mound, descending shaft, and tunnels that fork in two or three different directions. The mound entrance is plugged to prevent entrance of light.

Step 2: How to Trap Them

First, find the gopher mound. Got it? Brush the drt off the surface of the ground and feel for the plugged entrance hole. The dirt in this hole is usually very soft and easy to detect. Dig into this hole until it opens up and you can easially tell which way the tunnel is going.

Step 3: Place Your Traps.

Once you've felt the general direction of the traps, Go about a foot and a half from the mound and dig a hole that intersects the tunnel you felt earlier. Place the traps facing either direction in this tunnel, as shown in the crude but effective drawing. Place a peice of plywood or a large rock over the opening you just made and seal the edges with dirt. (Gophers hate light).

Step 4: Traps

The traps that I have found to be most effective are the so-called "Macabee" style impalers. When the gopher flips the panel forward, the two spikes impale him from both sides.
(Gruesome, isn't it?)

Step 5: Checking Your Traps

Tie each trap to a stake before putting them in the ground so that they won't be lost.
Check your traps every day, and if you don't get a gopher in two to three days, move them to another location.
Happy Killing!!