Water Rustlers is a 1939 American Western film directed by Samuel Diege.

Mr. Weylan purchases land in order to keep the water supply for himself, originally for hydraulic mining.

His long term scheme is when all the ranches fail due to their cattle having no water, he can buy their land cheaply and sell it to a meat company.

Weylan gets his way through fair means, such as having his lawyers getting the rancher's case thrown out of court, as well as foul means such as his henchmen murdering Shirley Martin's father and preventing witnesses to testify.

Shirley takes the law into her own hands to lead the ranchers in their fight for justice.