Long term flow of the Truckee River in California and Nevada

The Office of the Solicitor, Department of the Interior, requested the Geological Survey to evaluate the reliability of streamflow records in the Truckee River basin and to determine the long-term average annual runoff.

The reliability of streamflow records was evaluated by comparisons between pairs of records at six locations along the Truckee River between Lake Tahoe and Pyramid Lake.

The observed or estimated annual runoff near Nixon, Nevada was adjusted for changes in storage, evaporation losses, diversions, and depletions to approximate the inflow into Pyramid Lake under natural conditions.

The long-term average annual runoff near Nixon was computed on the basis of streamflow records since 1899. The long-term (124-year) record of precipitation at Sacramento and tree ring information were used to substantiate the conclusion that the average runoff during the 74 years of streamflow record is a reliable measure of the average runoff for a longer period.