2011–2017 California drought
This declaration followed a series of powerful Pacific storms during the first few months of the year, which coincided with the U.S. experiencing drought conditions in the fewest parts of the country since 2000.
Lack of rainfall had caused the mouths of rivers to be blocked off by sand bars which further prevented fish from reaching their spawning grounds.
Stafford Lehr, Chief of Fisheries within the California Department of Fish and Wildlife said that 95% of winter run salmon did not survive in 2013.
Although natural variability dominates, anthropogenic warming has substantially increased the overall likelihood of extreme California droughts.
"[11] Pritchett & Manning 2009 showed that the alkali meadow vegetation plant community is groundwater dependent and that this characteristic buffers the system from the effects of drought.
One of the reasons that the study was conducted was to ascertain whether the Owens Valley region of California could handle any practiced or proposed groundwater extraction.
[19][20] Experts also noted that due to the soil's extreme dryness and low groundwater levels, it would take significantly more rain—at least five more similar storms—to end the drought.
[23] In 2014, a study by the UC California Institute for Water Resources was released which found that rainfall has been abnormally high since the late 1800s.
In early 2014 the main stems of the Eel, Mad, Smith, Van Duzen, and Mattole rivers were closed pending additional rainfall.
[31] Other actions were also taken, such as releasing more water from the Kent Dam in hopes of raising the levels in the Lagunitas Creek watershed—one of the last spawning grounds that wild coho can still reach.
In the spring of 2015, the National Oceanic and Atmospheric Administration named the probability of the presence of El Niño conditions until the end of 2015 at 80%.
[34] The drought led to Governor Jerry Brown's instituting mandatory 25 percent water restrictions in June 2015.
[37] Heavy rains in January 2017 had significant benefit to the state's northern water reserves, despite widespread power outages and erosion damage in the wake of the deluge.
[39] The drought was largely alleved in California by a persistent weather pattern that allowed rounds of storm systems to consistently hammer the state, with the snowpack rising to well above average.
Beginning in 2008, millions of floating plastic shade balls were dropped on reservoirs to prevent evaporative losses and enhance water quality.
Scientists determined that the amount of time that the shade balls need to be deployed for the water costs in production to be balanced is between one and two and a half years.
As of June 2023, California's Department of Water Resources (DWR) has awarded over $70 million in an attempt to mitigate and help with local drought impacts as well as $217 million awarded to 44 projects that aim to help strengthen and prepare communities to be more resilient and prepared for the impacts of long term drought.
