![Lake Powell, 2006](/sites/default/files/styles/large/public/1024px-Lake_Powell_%282217173388%29.jpg?itok=HvybkJ2I)
![The Colorado River.](/sites/default/files/styles/large/public/Horseshoe_Bend_TC_27-09-2012_15-34-14.jpg?itok=TFmb00Tw)
![An ancient tree stump submerged in the West Walker River.](/sites/default/files/styles/large/public/Ingram_Fig_6.jpg?itok=Nw0dj6y7)
An ancient tree stump submerged in the West Walker River, eastern Sierra Nevada. (Photo courtesy of D. J. DePaolo.)
![A cut section of a Giant Sequoia trunk from Tuolumne Grove, Yosemite National Park, California.](/sites/default/files/styles/large/public/Screen%20Shot%202015-02-11%20at%208.36.58%20PM.png?itok=j72nmszC)
A cut section of a Giant Sequoia trunk from Tuolumne Grove, Yosemite National Park, California, showing AD dates of fires (photo courtesy of Thomas Swetnam, Laboratory of Tree-Ring Research, University of Arizona).
![Ancient pueblo cliff dwelling at Mesa Verde.](/sites/default/files/styles/large/public/Ingram_Fig_8.jpg?itok=xc_0Sj_o)
Ancient pueblo cliff dwelling at Mesa Verde, southwestern Colorado. (Photo taken by B. Lynn Ingram)
![Montezuma’s Castle, a cliff dwelling occupied by the Sinagua.](/sites/default/files/styles/large/public/Ingram_Fig_9.jpg?itok=TuML0O1O)
Montezuma’s Castle, a cliff dwelling occupied by the Sinagua, located just north of Camp Verde in central Arizona. (Photo by B. Lynn Ingram.)
![Mono Lake, California.](/sites/default/files/styles/large/public/Ingram_Fig_10_1.jpg?itok=kfE_JLZt)
Mono Lake, showing calcium carbonate “tufa tower” formations that originally formed beneath the lake but are now exposed after the water level dropped. The eastern flank of the Sierra Nevada range is shown in the background. (Photo by D. J. DePaolo.)
![Donner Lake, Sierra Nevada Range, California.](/sites/default/files/styles/large/public/Ingram_Fig_2_1.jpg?itok=utOFjIK0)
Donner Lake, Sierra Nevada Range, California (Photo taken by B. Lynn Ingram).
![Sacramento Valley, California.](/sites/default/files/styles/large/public/Ingram_Fig_3_2.jpg?itok=X0qbxDz-)
Frances Malamud-Roam, B. Lynn Ingram, and Christina Brady coring a small oxbow lake in the Sacramento Valley, California. (Photo taken by Anders Noren, University of Minnesota, LaCore curator.)
![San Francisco Bay, California sediment core.](/sites/default/files/styles/large/public/Ingram_Fig_4_3.jpg?itok=Vd7rMuhp)
Sediment core taken by Frances Malamud-Roam and B. Lynn Ingram from beneath San Francisco Bay, California. (Photo taken by B. Lynn Ingram.)
![Marsh Sediment, San Francisco Bay.](/sites/default/files/styles/large/public/Ingram_Fig_5_2.jpg?itok=ZnRON5ZJ)
Frances Malamud-Roam and Anders Noren coring marsh sediments adjacent to San Francisco Bay (Photo taken by B. Lynn Ingram)
![A photo of Shasta Lake and Shasta Dam in 1965.](/sites/default/files/styles/large/public/6507-ShastaLakeFull.jpg?itok=IazUBZL1)
![California's 'Save Our Water' Program.](/sites/default/files/styles/large/public/SaveOurWaterLogo.png?itok=QQ4rTWgU)
![Folsom Lake.](/sites/default/files/styles/large/public/1503336_10151945368217449_268621756_n.jpg?itok=_gnCzkT3)
![Oroville Lake, California.](/sites/default/files/styles/large/public/1497201_10151945367972449_231099544_n.jpg?itok=urBC2H-Q)