This Obscure Laboratory on Donner Summit Holds Answers to California’s Water Future. But Hardly Anyone Knows it Exists.

At the top of Donner Summit, an old cabin rests in a thicket of tall trees. The structure is three stories tall, including the basement. Still, in the heaviest of winters, the snow drifts are deep enough to bury the front door, so the only way into the building is through a window on the top floor.