LAKE TAHOE (CBS13) — Video has surfaced of a work crew sending a massive boulder tumbling down a hillside near Emerald Bay in South Lake Tahoe.

The Tahoe Regional Planning Agency says it found evidence the boulder damaged the mountain slope and trees below Highway 89.

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Officials say the Redding-based contractor could now face civil penalties for causing environmental damage to the site.

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Investigators are now reviewing the video where a Stewart Engineering highway contractor laughs as a giant slab of rock tumbles down a hill below Highway 89, taking out trees and flattening shrubs.

Caltrans hired the company for $4 million to do road improvements on a portion of the highway at Emerald Bay and install a 192-foot retaining wall. It was supposed to be finished the day after the video was shot in May.

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Caltrans has hired an arborist to see what vegetation needs to be replanted or replaced and to develop a plan to make sure the picturesque part of Northern California is restored to its former glory.