In May 1952, the island was sold to the Leslie Salt Company, at the time "the largest salt producer on the West Coast and possibly the largest solar evaporation operation in the world". It was one of several islands in the Napa River purchased by the company (the total purchase included Edgerly Island, Little Island, Knight Island, Banty Island, Island No. 2, and part of Island No. 1). Leslie planned to flood and dike the islands to develop them into salt ponds; the entire project was projected to cost $3,500,000 ($ in ), and be ready for the first harvest in 1958. The salt was to be carried on barges down the Napa River, and primarily used in chemical plants. During the 1950s, this project was carried out, and Russ Island became a salt evaporation pond.
