Agriculture accounts for roughly 80 percent of the water used by people in California. “Roughly” because, unlike urban water districts, farm-water suppliers reveal little about how much of the state’s most precious resource goes into irrigation ditches and fields. That lack of basic public information from a behemoth water consumer was one reason the state passed a 2007 law requiring irrigation districts to start coughing up a modicum of so-called “farm-gate” data. The state form, to be filed with the Department of Water Resources, asks a bare handful of essential questions, on a single page.