Buried utility cables and irrigation lines can be protected by enclosing them in various materials, as long as the outside diameter exceeds 2.9 inches (7.4 cm). Gophers can open their mouths only wide enough to allow about a 1-inch (2.5-cm) span between the upper and lower incisors. Thus, the recommended diameter presents an essentially flat surface to most pocket gophers. Cables can be protected in this manner whether they are armored or not. Soft metals such as lead and aluminum used for armoring cables are readily damaged by pocket gophers if the diameters are less than the suggested sizes.
Buried cables may be protected from gopher damage by surrounding the cable with 6 to 8 inches (15 to 20 cm) of coarse gravel. Pocket gophers usually burrow around gravel 1 inch (2.5 cm) in diameter, whereas smaller pebbles may be pushed to the surface.
Resources: (online)
Pocket Gophers
