Quake Lake, also called Earthquake Lake, is one of the more interesting natural features in Montana. Quake Lake was formed when an earthquake measuring 7.5 on the Richter Scale rocked this part of Montana on August 17th, 1959.
The earthquake was so strong that it triggered a massive landslide on Sheep Mountain, on the western end of Madison Canyon (nine miles downstream from Hebgen Dam), which blocked the Madison River completely. Additionally, the north shore of Hebgen Lake, which lies just upstream, dropped an amazing 19 feet, cracking Hebgen Dam in four places and creating massive waves on the lake that spilled over the dam and raced downstream in a massive flood.
The landslide also caused tornado force winds that fanned out in front of the landslide and flood, destroying most everything in its path. Three different sections of Highway 287 slid into the newly formed lake and numerous cabins along the former Madison River were damaged or completely destroyed.
The result of the quake is that twenty-eight people died from the landslide and five more died from the resulting flood. The Madison River below the landslide dried up completely for a time, resulting in significant fish kill.
The Army Corps of Engineers, in a race against time, blasted a channel through the landslide, allowing the Madison River to resume its flows before a catastrophic flood would have happened if the newly formed lake had crested over the landslide.
The barren spot on the mountain is where the landslide happened that blocked the Madison River, thus allowing the formation of Quake Lake
Following all of this, Quake Lake – also known as Earthquake Lake – was formed. Quake Lake measures six miles long, up to a third of a mile wide, covers 611 acres and is more than 180 feet deep. It offers decent fly fishing for brown and rainbow trout.
As Quake Lake flooded much of the former Madison River canyon, thousands of dead trees poke up through the water. These trees, combined with the countless trees that are completely submerged, provide excellent cover and habitat for trout, although it can complicate the fishing. Fly fishing can be excellent using dry flies around the dead standing timber.
The best fishing on Quake Lake occurs in late spring and early summer, and again later in the summer and fall. During the height of run-off, the lake turns cloudy, severely limiting fly fishing opportunities.
Fishing pressure ranges from low to moderate. The least fishing pressure happens during the off-season and on weekdays. One note of caution: Highway 287 is busy during the summer, so expect a fair amount of road noise.
Access to the lake is excellent. Shore fishing is possible from anywhere along Highway 287, and a boat ramp also exists, although it is rather hidden. Winds can occasionally be a problem on the lake, and combined with a current and lots of hidden obstructions, Quake Lake poses challenges for boaters.
Those with motorboats need to pay attention for submerged, standing timber that can easily destroy a prop. For those lacking a motorboat, inflatable boats that are easy to paddle such as inflatable flatwater kayaks and pontoon boats work well provided the winds aren’t too strong.