The Lahontan Basin Area Office (LBAO) has jurisdiction over a large area of the Great Basin including most of the northern two thirds of Nevada with a small amount of overlap into California and Oregon. 

Much of this expanse was covered by ancient Lake Lahontan that existed during the last ice age, and whose surface area peaked nearly 13,000 years ago at 8500 square miles.    Map

The main area of LBAO activities is in the Carson, Truckee, and Humboldt river basins, where there are four operating Reclamation projects