Water transfers are an important way to share a limited resource, especially to help fish and habitats that were historically left with scraps when water rights were parceled out around the West. The water for such transfers usually comes from farmers, who free up water through some kind of conservation measure. By transferring the saved water, a farmer can help imperiled fish and make some money. Such arrangements are especially important on the Colorado River, which is oversubscribed to serve human demands and also feeds a vast international ecosystem.