STORY AND PHOTOS BY KAREN BOSSICK

The Sawtooth National Recreation Area completed its new boat launch at Stanley Lake just in time.

The inlet at Stanley Lake—a popular boat launch, beach and fishing area—apparently collapsed during the past five weeks as a result of the March 31 earthquake that rocked Idaho and beyond.

The Sawtooth National Forest reported in a Facebook post that the area was “flooded with deep water and had seemingly disappeared,” erasing a trail and boardwalk.

With the melting of winter snowpack and ice at lakes in the Sawtooth National Recreation Area, several observers noted something was different,” officials wrote.

Geologists with Idaho Geological Survey went on to review photos and pre- and post-earthquake satellite imagery of the inlet and linked the flooding with geologic processes associated with the magnitude 6.5 earthquake.

“The most probably cause for the disappearing of the inlet delta is a combination of liquefaction and compaction of saturated sediments and some possible sliding and lateral spreading on the delta toward the deeper part of the lake as a result of the March 31 earthquake of the associated aftershocks,” said Claudio Berti, director and state geologist with the Idaho Geological Survey.

On Sunday boaters enjoying a sunny Mother’s Day with temperatures approaching 70 seemed oblivious to the flooding which washed over what had been dry land, matting down tall grasses. The earthquake appeared to have affected an area more than the length of a football field from what had been the edge of the inlet.

Hikers tried to follow the Lakeshore boardwalk only to find it turning down into water. Others who had hoped to do a short loop on the Stanley Lake trail found their path underwater, as well.

The loss of the inlet beach for recreation is unfortunate because the area was so popular, said Brian Anderson, deputy area ranger for the SNRA.

But he noted that the SNRA built a new boat ramp in 2019, which replaced the old boat launch. It also removed aging campground infrastructure from the shoreline near the inlet, replacing it with a new Stanley Lake Campground at the east end of the lake.

Berti and others will further research the area in the coming weeks.

The earthquake, which struck near the Cape Horn area northwest of Stanley, could be felt as far away as Calgary, Alberta, and parts of Nevada.

It caused significant structural cracks on the Custer County courthouse in Challis. It sent massive amounts of snow sliding onto Highway 20 near Banner Summit and even on Galena Summit. And it caused some impressive snow avalanches throughout the Sawtooth and Smoky Mountains, even toppling the 75-foot thick Arrowhead above the Cramer Lakes in the Sawtooth Mountains.

There have been more than 350 aftershocks greater than 2.0 magnitude since the March 31 quake. A 3.6 quake was even recorded May 8.

Likely, more changes will be found as people begin to take to the backcountry around Stanley and Challis.