The Orr Ditch decree was entered by the U.S. District Court for the District of Nevada in 1944 in United Statesv. Orr Water Ditch Co., et al. The decree was the result of a legal action brought by the United States in 1913 to fully specify who owned water rights on the Truckee River and had rights to storage in Lake Tahoe. The Orr Ditch decree adjudicated water rights of the Truckee River in Nevada and established amounts, places, types of use, and priorities of the various rights, including the United States’ right to store water in Lake Tahoe for the Newlands Project. The decree also incorporated the 1935 Truckee River Agreement among Sierra Pacific Power Company (now Truckee Meadows Water Authority), TCID, Washoe County Water Conservation District, Department of the Interior, and certain other Truckee River water users.
The Truckee River Agreement is an operating agreement that, among other things, provided for a reduced flow rate at the California-Nevada state line, and for the construction of what is now Boca Reservoir. The Orr Ditch decree, 1915 Truckee River General Electric decree, and Tahoe-Prosser Exchange Agreement provide the current operational framework and rules for Truckee River reservoirs. The provisions of the Orr Ditch decree are administered by the Federal Water Master appointed by the Orr Ditch court.