In the desert southwest, water travels all the way from the Colorado River to farmers’ fields through a massive and ingenious system of irrigation canals. To make sure the right amount of water flows to each field at the desired time is the job of the “zanjero” or ditch-tender. Living on Earth’s Ingrid Lobet spent a day with José Romo, a zanjero who’s been delivering water to farmers in California’s Imperial Valley for more than three decades.