Long-term climate trends and water management history in California. Poster given at "Weathering Change: Impact of Climate Change and SGMA on CA Water" in Davis, CA (April 4-5).

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800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000
DroughtAreaIndex(%)
Year (AD)
Most of California’s dynamic relationship with water takes place
within a relatively wet period of history (Cook et al., 2004). The
Drought Area Index defines the extent to which a defined
threshold of the Palmer Drought Severity Index (PDSI) is
exceeded. The figure below shows that California’s climatological
history oscillates between dry (red) and wet (blue) periods relative
to the mean PDSI.
Hanak et al. (2007) characterizes four “eras” of California’s
complex water history, depicted in the timeline to the right. Note
that most policies were enacted during the latest wet period in
California’s history; however, the occurrence of 200-year
megadroughts in the distant past, as well as other decades-long
droughts later on, suggest the possibility of extended dry periods
in the future. Legislation such as the 2014 Sustainable
Groundwater Management Act (SGMA) is meant to prepare for
this possibility, but it means changing the way that water has
previously been managed in California.
1850: California becomes a state
Medieval megadroughts
Sources: [1] Cook, E. et al. 2004. Long-term aridity changes in the western United States. Science,
306, 1015-1018. [2] Hanak, E. et al. 2011. Managing California’s Water: From Conflict to Reconcilia-
tion. Public Policy Institute of California.
THE PAST, THE PRESENT, AND THE FUTURE
Long-term Climate Trends and Water Management History in California
Marielle Pinheiro1
and Rich Pauloo1
1. Land, Air and Water Resources, University of California, Davis. Author contact: mcpinheiro@ucdavis.edu, rpauloo@ucdavis.edu
English
common
law
adopted
(1850)
Gold Rush
begins
(1848)
SWP
approved
(1960)
Water policy
legislation
(2009)
Right of prior
appropriation
established
(1855)
Reclamation
districts
authorized
(1868)
Widespread flooding
(1906, 1909)
Reasonable use doctrine (1928)
Federal Flood Control Act (1928)
NEPA (1969)
Porter-Cologne Act (1969)
California Wild and
Scenic Rivers Act (1972)
Delta Stewardship
Council (2010)
California Aqueduct
(1966)
North Coast rivers
declared wild and
scenic (1981)
Irrigation districts
authorized
(1887)
Federal
takeover
of CVP (1935)
End of
hydraulic
mining
(1884)
Delta
Mendota
Canal
(1951)
Central Valley
flood
legislation
(2007)
Reclama-
tion Act
(1902)
Raker Act
authorizes
Hetch
Hetchy
(1913) Rejection of
peripheral canal
(1982)
Riparian rights
held as superior to
appropriative rights
(1886)
Section 5937
Fish and Game Code
(1933)
Bay-Delta Accord
(CALFED) (1994)
CALFED
Record of
Decision
(2000)
Collapse
of
CALFED
(2006)
O’Shaughnessy
Dam (1923)
Colorado River
Aqueduct (1940)
Hoover Dam
authorized (1928) Trinity Dam (1962)
Oroville Dam (1968) Clean Water
Act (1972)
Federal
ESA
(1973)
CEQA (1970) CVPIA (1992)
Owens River
Aqueduct
(1913)
Shasta
Dam
(1944)
Mono
Lake
decision
(1983)
Great Flood
of 1862
1840 0091 0091 1950 2000
Laissez-Faire Era Hydraulic Era
Local Organization Era Era of Conflict
Sustainable
Groundwater
Management Act
(2014)
All critically overdrafted
basins managed under a
Groundwater Sustainability
Plan (2020)
All critically overdrafted basins
achieve sustainability (2040) --
assuming plans are adopted
on time in 2020
2050
Era of Reconciliation?
Future Climate:
Wet or Dry?
Questions to Consider:
What variability in California’s future
climate is possible?
How will climatic variability
influence California’s relationship
with water?
Can California transition from
an Era of Conflict to an Era of
Reconciliation? What will that
transition look like?
Water law timeline: Modified from Hanak et al. (2007), Figure 1.1. Drought area index figure: Recreated from
Cook et al. (2004), Figure 2A. Drought area index data from E. Cook, personal communication, February, 2016.
Figures created or modified by Rich Pauloo, Marcos Pinheiro and Marielle Pinheiro.
Acknowledgements: Supported by NSF DGE # 1069333, the
Climate Change, Water, and Society IGERT, to UC Davis.
*
* The Sacramento flood of 1860,
as well as the 2017 La Niña
storms following the most
recent drought in California in-
dicate that periods of drought
may be accompanied by ex-
treme precipitation events.