In 1935, the California Supreme Court ruled in the case of Tulare v. Lindsay-Strathmore that drowning gophers was, self-evidently, not a “beneficial use” of the state’s precious water resources. Also squirrels:

Another gave it as his reason for irrigating in winter that “every time we irrigate we kill gophers … the best season of the year to kill gophers is with cold water, irrigate in cold weather and kill them. The same thing with squirrels. You irrigate the squirrels in cold weather, in February, he gets wet and comes out and freezes to death.” Many other quotations could be made to the same effect. A great many of respondents’ witnesses seemed to be of the opinion that the only reason they irrigated during the winter season was to exterminate these pests. It seems quite clear to us that in such an area of need as the Kaweah delta the use of an appreciable quantity of water for such a purpose cannot be held to be a reasonable beneficial use. This seems to us so self-evident that no further discussion of the point is necessary.