Crowds, erosion and flooding threaten Washington, D.C.'s cherry blossoms

Washington, D.C.'s Tidal Basin is transformed every spring as nearly 4,000 cherry trees bloom, drawing about 1.5 million visitors during March and April. But the crowds, as well as erosion and a lack of repairs, are overwhelming, and the national treasure now faces an uncertain future.

Look up and you see pastel pink petals. Look look down and you'll see big holes, mud and a walkway crumbling under the weight of sinking earth, rising tides and too many tourists in search of a perfect selfie.

We saw people with canes, crutches and suitcases navigate a rough patch right next to the water. And at high tide, a sidewalk in some parts disappears, leaving not just people but century-old trees threatened.

"You will actually see the roots are not only compromised but actually exposed," said Jason Clement, marketing director for the National Trust for Historic Preservation. 

The National Park Service says it's time for change. The Park Service and the National Trust for Historic Preservation are turning to the public for help – announcing a $750,000 ideas lab, a sort of "Shark Tank" for the Tidal Basin.

"This is not just D.C.'s calling card to the nation; it's America's calling card to the world," Clement said. "It is sinking, and it is flooding, and there is over $500 million in deferred maintenance that needs to be invested in this park so that it can be saved for future generations." 

The National Park Service estimates it will cost $330 million just to fix just the sea walls.

"It's a concern for visitors and, quite frankly, it's a concern of ours. We certainly share people's frustration," said National Park Service spokesperson Mike Litterst.

Some are calling for an even more dramatic redesign of the Tidal Basin, but that will cost hundreds of millions. We'll get our first look at those ideas sometime early next year.