Quake Lake

August 17, 1959 - The biggest earthquake in Montana history struck at 11:37pm on this day. It triggered a massive landslide that sent 80-million tons of rock and debris tumbling down Sheep Mountain where it formed a 220-foot dam across the Madison River.

Tragically, hundreds of campers along the river and nearby Hebgen Lake were directly in the landslide’s path. 28 people died.

The scale of the upheaval is mind-blowing. 50 square miles of the lake bottom dropped 10 feet. 30 miles away in Yellowstone National Park, geysers and hot springs turned muddy from the disruption. Aftershocks would continue for weeks.

And the danger was just getting started, because rising water behind the newly formed debris dam could trigger a breach or overflow that would send a tidal wave of water and rock into the downstream town of Ennis. Hundreds of workers from the U.S. Army Corps of Engineers worked around the clock to build a spillway and other reinforcements to prevent a second disaster.

Quake Lake is now six miles long with a surface area covering over 600 acres. It’s a testament to the unpredictable and unfathomable power of nature to reinvent the landscape in the blink of an eye.