Who determines how much water California can use from the Truckee River before it reaches Nevada?

An agreement between California and Nevada called an “interstate allocation” spells out how much water is available to each State from Lake Tahoe, the Truckee River and the Carson River. This allocation was negotiated by the two States in the 1960s, when Ronald Reagan was Governor of California and Paul Laxalt was Governor of Nevada. This interstate apportionment of water protects water users in northern Nevada. It will ensure that water users in northern Nevada have the rights in Lake Tahoe and the Truckee and Carson Rivers that they have sought since the 1960s, and that no contrary claims based on changes in uses that have occurred since the initial agreement will be allowed. Under the interstate allocation, Nevada will receive 90 percent of Truckee River flows produced in California. The agreement was approved by Congress in Public Law 101-618, but conditioned on implementation of TROA. For the interstate allocation to become effective, Public Law 101-618 requires that TROA must be implemented.