Mount Rainier National Park geologist Scott Beason said a small glacial outburst flood on the Nisqually River occurred Oct. 27.
The event took place about 9 p.m., but was localized in scale and did no damage to park facilities. Beason said the outburst was not caused by volcanic action.
He said it likely originated from the Nisqually Glacier because of moderate to intense rain at that time.
A stream gauge on the Nisqually river located at Longmire registered a 2.8-foot rise in river’s level between 8:30-9:45 p.m. The spike was measured on other gauges downstream of the park.
Checks of the area show evidence of a several-foot surge of water in the river, Beason said.
While this event was small, it highlights one of the many hazards at Mount Rainier, Beason said. It also shows that destructive and hazardous events can occur even during small storms that are common in the fall and winter at Mount Rainier.
Such outburst floods have happened in the park before on four of Mount Rainier’s glaciers: Nisqually, Kautz, South Tahoma and Winthrop. From 1986-1992, South Tahoma Glacier had 15 outbursts, with the resulting floods washing out parts of the West Side Road.
The outbursts become a danger when the floods start moving rock, sediment and other debris downhill. Think of it as turning a hose onto a pile of gravel. The result is a debris flow.
The largest known debris flow in park history occurred Oct. 2-3, 1947, when heavy rains fell on the end of the Kautz Glacier. The resulting debris flow traveled 5.5 miles and buried Nisqually-Paradise Road under 28 feet of mud and debris. An estimated 50 million cubic yards of sediment were moved by the flow.
In 2005, a debris flow on Van Trump Creek was captured on video as it roared over Christine Falls. You can see that video on YouTube at youtu.be/SrYqJlCuppA. At the 30-second mark, you can see rocks and small boulders floating downstream.
LAKE CRESCENT ESCAPE
People looking for a winter escape at Olympic National Park, should consider a weekend getaway by staying at one of the Roosevelt Fireplace Cabins at Lake Crescent.
Each of the four cabins, listed on the National Register of Historic Places, offer a fireplace combined with lake or mountain views.
The cottages are available Fridays-Sundays only in the winter. Rates are $210.50 per night.
There are two two-bedroom cottages with two double beds in one bedroom and one queen bed in the other. These cottages also have a full bathroom, a microwave and a mini-fridge.
The two one-bedroom cottages have two queen beds in the bedroom, a fireplace, a shower-only bathroom, a microwave and a mini-fridge.
None of the cabins has a TV or telephone.
For reservations, call 800-204-3116.