"The Winning of Barbara Worth" by Harold Bell Wright
As a child, Barbara is orphaned when her settler parents perish trying to cross a California desert. She is rescued and raised by Jefferson Worth, who dreams of irrigating the desert. With his new charge in tow, Jefferson attempts to turn arid land into a productive field, but he soon finds himself coming toe-to-toe with his boss, Mr. Greenfield, a man with many resources and few scruples.