The 2014 California Drought - Dealing with Extreme Dryness From A Hydroelectric Planning Perspective

TitleThe 2014 California Drought - Dealing with Extreme Dryness From A Hydroelectric Planning Perspective
Publication TypeConference Proceedings
Year of Conference2014
AuthorsFreeman, Gary J.
Conference Name82nd Annual Western Snow Conference
Series TitleProceedings of the Western Snow Conference
Date Published2014
Conference LocationDurango, Colorado
Keywordsclimate change, drought, hydroelectric, reservoirs, Sierra

The 2013 calendar year was the driest year on record for California. For San Francisco based Pacific Gas and Electric Company (PG&E), which operates the largest investor owned hydroelectric system in the United States, the water management planning challenges, which were encountered during the first three months of 2014 and the twelve unusually dry months preceding 2014 were unlike those of earlier droughts. The acceptance of both the concept of climate change impacts as well as new paleo-climatological research findings about California and the southwest were for the first time being given serious consideration in the Company’s water release planning. The prospect that the persistent high pressure region blocking the storm track into California fromthe Eastern Pacific and Gulf of Alaska could possibly remain “parked in place” became a principal scenario needed for effective planning. In terms of snow water equivalent (SWE), the February 2014 statewide snow surveys were less than 15% of the historical February 1 average. The demands on downstream water release requirements for maintaining biological flows, whitewater rafting, and other recreational opportunities have continued to increase in the past 38- 39 years from the 1976-1977 drought, which were two successive very severe dry years. Conditions leading into the 2014 drought included 15-years of generally declining wetness over much of California causing the northern California’s porous volcanic aquifer storage to decline significantly from the aquifer’s relatively high mid-1990’s storage state. Also water year runoff from rain-shadowed areas of the northern California’s Sierra and southern Cascades have been in a state of trending decline since the 1976-1977 drought, a condition likely attributable to impacts from climate change. Utilizing the latest research findings available in 2014 on climate change and drought, the approach to reservoir and power production planning at PG&E changed from that utilized with prior droughts. Rather than assuming median likelihood or some low level of exceedances probability for remaining seasonal precipitation, the planning would take place as if the high pressure system pattern would continue to persist with no additional runoff expected.