Melting of this year's massive Sierra Nevada snowpack will cause California rivers to surge and possibly overflow their banks well into the summer this year.

Among the first to be affected will be the Merced River running through Yosemite National Park , which is expected to crest today.

(Mark Boster / Los Angeles Times)

Cook's Meadow: Richard DeYoung and his granddaughter Sienna Milandin walk through a flooded portion of the meadow in the Yosemite Valley with Yosemite Falls in the background.

(Mark Boster / Los Angeles Times)

Upper Yosemite Falls: The water at the base of Upper Yosemite Fall crashes into the granite below in Yosemite Valley.

(Mark Boster / Los Angeles Times)

Flooded pathways: Bicycle riders have to walk their bikes across flooded pathways in the Yosemite Valley.

(Mark Boster / Los Angeles Times)

Submerged: One little visitor to the Yosemite Valley walks away from a one of the flooded sections of the wooden walkways that traverse the meadows.

(Mark Boster / Los Angeles Times)

Picture perfect: A photographer frames his shot while standing on Swinging Bridge as Yosemite Falls is reflected in the flood level waters of the Merced River.

(Mark Boster / Los Angeles Times)

Spring bloom: Dogwood blossoms dangle above the Merced River reflecting some of the colors of the setting sun in the Yosemite Valley next to the Pohono Bridge.

(Mark Boster / Los Angeles Times)

Mighty Merced: The water in the Merced River churns and roars near the Pohono Bridge.

(Mark Boster / Los Angeles Times)

Tunnel View: Visitors stop at Tunnel View in Yosemite National Park for a picture with Bridalveil Falls roaring in the background.