Will TROA decrease water flows in the Truckee Canal to the Newlands Project?

The Department of the Interior completed extensive modeling of the Truckee River system including examining the current conditions with and without TROA and future predicted conditions with and without TROA. This modeling determined that the change, if any, in the amount of Truckee River water available for diversion at Derby Diversion Dam would depend on whether upstream water users had fully utilized their senior priority rights. A limited amount of the water which previously has been available for diversion to the Newlands Project results from upstream water right holders not fully exercising their water rights. TROA allows for more efficient exercise of those water rights, and, in the future, water right holders will find ways to more efficiently use those rights, particularly in dry periods. Such future uses of water rights could also occur in the absence of TROA.

Model results from the TROA Environmental Impact Statement based on the past 100 years of hydrology show the same number of shortage years occurred with or without TROA and the difference in the Truckee Canal diversions was less than 2 percent. Attached are two graphs showing the modeling results, with and without TROA, in the Truckee and Carson Divisions of the Project.