Red River Valley (1936) on Netflix

Plot summary

Drought has left the landowners of Red River Valley without water, and an irrigation system under construction is meant to bring it to them. Five men who oversaw the work have been murdered, and Gene is hired as a ditch rider, patrolling the ditches to keep them working and guard against sabotage. His friend Frog Millhouse rides with him. Mary Baxter and her father George head the Red River Land and Irrigation Company, where Steve Conway also works. On Gene's first night on the job, he and Frog are nearly killed, and the two of them take up the hunt for whoever has been causing the accidents at the dam.