RESPONSE OF ENDORHEIC PYRAMID LAKE TO CLIMATE CHANGE AND MANAGEMENT PRACTICES IN THE TRUCKEE RIVER BASIN

The Truckee River Basin in California and Nevada connects headwaters flowing from Lake Tahoe (496 km²) to its terminus at Pyramid Lake (487 km²) in the western Great Basin. Lake water levels and the ecological health of such endorheic systems are particularly sensitive to changes in precipitation and runoff regimes as well as to consumptive water uses within the watershed. Pyramid Lake is an example of a terminal lake that has experienced several extremes in lake levels. It is a remnant of ancient Lake Lahontan, which during the Pleistocene extended over much of the western Great Basin. Several endemic species still exist, including the Lahontan cutthroat trout and the cui-ui, although their persistence is compromised by reduced flows into the lake. Derby Dam, for example, was constructed by the U.S. Bureau of Reclamation from 1903-1905 on the Truckee River between Reno and Pyramid Lake to divert water into the Carson River watershed for agricultural uses. In this presentation the current Truckee River Basin management practices are evaluated in context of anticipated climate regime changes and paleoclimate reconstructions derived from Lake Tahoe and other terminal lakes in the region.