Bulletin No. 39-57, Water Supply Conditions in Southern California during 1956-1957, Volume II, Precipitation and Water Level Data Central Coastal and Los Angeles Regions

California Department of Water Resources (DWR) | June 16th, 1958

Bulletin No. 39-57 Volume I Bulletin No. 39-57 Volume III Bulletin No. 39-57 Volume IV

Bulletin No. 39-57 Volume I Bulletin No. 39-57 Volume III Bulletin No. 39-57 Volume IV

Bulletin No. 39-57, Water Supply Conditions in Southern California during 1956-1957, Volume III, Precipitation and Water Level Data Lahontan, Colorado River Basin, Santa Ana, and San Diego Regions

California Department of Water Resources (DWR) | June 16th, 1958

Bulletin No. 39-57 Volume I Bulletin No. 39-57 Volume II Bulletin No. 39-57 Volume IV

Bulletin No. 39-57 Volume I Bulletin No. 39-57 Volume II Bulletin No. 39-57 Volume IV

Bulletin No. 39-57, Water Supply Conditions in Southern California during 1956-1957, Volume IV Cross-Indexes

California Department of Water Resources (DWR) | June 16th, 1958

Bulletin 39-57, Volume I Bulletin 39-57 Volume II Bulletin 39-57 Volume III

Bulletin 39-57, Volume I Bulletin 39-57 Volume II Bulletin 39-57 Volume III

Bulletin No. 39-58, Water Supply Conditions in Southern California during 1957-1958, Volume I

California Department of Water Resources (DWR) | August 1st, 1960

Bulletin No. 39-59, Water Supply Conditions in Southern California during 1958-1959, Volume III, Water Level Data Lahontan, Colorado River Basin, Santa Ana, and San Diego Regions

California Department of Water Resources (DWR) | May 1st, 1961

California forest die-off linked to multi-year deep soil drying in 2012–2015 drought

Nature Portfolio (Springer Nature) | July 1st, 2019

Widespread episodes of recent forest die-off have been tied to the occurrence of anomalously warm droughts, although the underlying mechanisms remain inadequately

Widespread episodes of recent forest die-off have been tied to the occurrence of anomalously warm droughts, although the underlying mechanisms remain inadequately understood. California’s 2012–2015 drought, with exceptionally low precipitation and warmth, and widespread conifer death, provides an opportunity to explore the chain of events leading to forest die-off. Here, we present the spatial and temporal patterns of die-off and moisture deficit during California’s drought, based on field and remote sensing observations. We found that die-off was closely tied to multi-year deep-rooting-zone drying, and that this relationship provides a framework with which to diagnose and predict mortality. Marked tree death in an intensively studied Sierra Nevada forest followed a four-year moisture overdraft, with cumulative 2012–2015 evapotranspiration exceeding precipitation by ~1,500 mm, and subsurface moisture exhaustion to 5–15-m depth. Observations across the entire Sierra Nevada further linked tree death to deep drying, with die-off and moisture overdraft covarying across latitude and elevation. Unusually dense vegetation and warm temperatures accelerated southern Sierran evapotranspiration in 2012–2015, intensifying overdraft and compounding die-off by an estimated 55%. Climate change is expected to further amplify evapotranspiration and moisture overdraft during drought, potentially increasing Sierran tree death during drought by ~15–20% °C−1.

California Water Action Plan (2016 Update)

State of California | January 1st, 2016

California is currently experiencing one of the worst droughts in memory. The 2016 water year is off to a good start, but with four consecutive dry years and the record l

California is currently experiencing one of the worst droughts in memory. The 2016 water year is off to a good start, but with four consecutive dry years and the record low snowpack of 2015, drought conditions may continue for a fifth straight year. Flooding in the midst of drought is likely, given strong El Niño conditions in the Pacific Ocean. Nothing focuses Californians’ attention on our water resources like the extremes of flood and drought. There is broad agreement that the state’s water management system is currently unable to satisfactorily meet both ecological and human needs, too exposed to wet and dry climate cycles and natural disasters, and inadequate to handle the additional pressures of future population growth and climate change. Solutions are complex and expensive, and they require the cooperation and sustained commitment of all Californians working together. To be sustainable, solutions must strike a balance between the need to provide for public health and safety (e.g., safe drinking water, clean rivers and beaches, flood protection), protect the environment, and support a stable California economy. This action plan lays out our challenges, our goals and decisive actions needed now to put California’s water resources on a safer, more sustainable path. While this plan commits the state to moving forward, it also serves to recognize that state government cannot do this alone. Collaboration between federal, state, local and tribal governments, in coordination with our partners in a wide range of industry, government and nongovernmental organizations is not only important—it is essential. The input and contributions received from all of these partners throughout the drafting of this action plan have resulted in a comprehensive and inclusive plan.

California's most significant droughts: Comparing historical and recent conditions

California Department of Water Resources (DWR) | March 23rd, 2015

The water years of 2012-14 stand as California’s driest three consecutive years in terms of statewide precipitation, and as of this writing in February 2015 the drought

The water years of 2012-14 stand as California’s driest three consecutive years in terms of statewide precipitation, and as of this writing in February 2015 the drought is continuing on. This report was prepared to compare the hydrology and impacts experienced during 2012-2014 with those of California’s largest historical droughts, in response to questions from local water agencies and others regarding the drought’s relative severity and the changed conditions since our prior major droughts. California’s immediately prior drought of statewide scale occurred in 2007-09; it was the first drought for which a statewide proclamation of emergency was issued. The 2012-14 period now marks the second time a statewide proclamation of emergency has been issued for drought. California’s most significant historical statewide droughts were the six-year drought of 1929-34, the two-year drought of 1976-77, and the six-year event of 1987-92. These droughts stand out in the observed record due to their duration or severe hydrology. The 1929-34 event occurred within the climatic context of a decades-plus dry period in the 1920s-30s whose hydrology rivaled that of the most severe dry periods in more than a millennium of reconstructed Central Valley paleoclimate data. The drought’s impacts were small by present-day standards, however, since the state’s urban and agricultural development was far less than that of modern times. The 1976-77 drought, although brief in duration, was notable for the severity of its hydrology. The 1987-92 drought was California’s first extended dry period since the 1920s-30s, and provides the closest comparison for drought impacts under a present-day level of development. The 2012-14 event set other records in addition to that of driest three-year period of statewide precipitation. The drought occurred at a time of record warmth in California, with new climate records set in 2014 for statewide average temperatures. Records for minimum annual precipitation were set in many communities in calendar year 2013. Calendar year 2014 saw record-low water allocations for State Water Project and federal Central Valley Project contractors. Reduced surface water availability triggered increased groundwater pumping, with groundwater levels in many parts of the state dropping 50 to 100 feet below their previous historical lows. These record-setting conditions speak to the need for continued improvement of our ability to respond to dry conditions. Knowledge of the impacts historically experienced in our past large droughts and the lessons learned during those events can help us be better prepared.

California's Water Supply Strategy: Adapting to a Hotter, Drier Future

Office of Governor Gavin Newsom | August 11th, 2022

California's Water Supply Strategy: Adapting to a Hotter, Drier Future

California Department of Water Resources (DWR) | August 16th, 2022