DARRINGTON — The Sauk-Suiattle Indian Tribe has long been concerned about the Sauk River flooding near its reservation.
A new report commissioned by the tribe forecasts the likely effects global warming will have on the reservation.
That report, completed in June 2014 by Seattle consulting firm Natural Systems Design and recently made public, confirms and puts numbers on what the tribe has long suspected: in the coming decades, the magnitude of flooding is expected to increase 50 percent while the frequency of flooding will more than double.
“Severe and irretrievable damages, and possible loss of life, are an inevitable consequence of failing to move residents and facilities out of their current location,” the report states.
As a result, the tribe is considering moving to land it purchased near Darrington earlier this year.
It would take an act of Congress to make that new property the official reservation. The alternative is that the existing reservation may soon find itself under water.
“I just want to push D.C. for reservation status to move to the new lands,” said Kevin Lenon, the vice chairman of the tribe.
Lenon will be in Washington, D.C., on Wednesday, armed with the global warming study, for the White House Tribal Nations Conference, where he hopes to be able to make his case with President Barack Obama.
On Nov. 25, with rain falling in what felt like a continuous stream, Lenon walked along the eastern edge of the reservation with Scott Morris, the tribe’s water quality coordinator.
About 50 feet behind the easternmost row of houses, the land drops about two feet down to a forested wetland tangled with underbrush.
The main channel of the Sauk River was about 1,000 feet farther east, behind a stand of 60-year-old alders.
Over the decades, the main channel has migrated all the way across the valley, in 1998 kissing a bluff on the east side, before wending back to its present location.
But aerial photography from 1949 shows the west bank of the Sauk was once where Lenon and Morris stood a week ago. That former channel is known as Reservation Slough, and just because the river hasn’t flowed through it recently doesn’t mean it won’t come back.
On that rainy Tuesday, however, the immediate concern was not the river’s eventual migration back, but whether the rain would cause the river to back up into the slough that night.
When the water flow on the Sauk River gauge nearest the reservation reaches 30,000 cubic feet per second, Morris goes on flood watch, monitoring the river once per hour until the flow drops back down.
The river didn’t reach that level Tuesday, but since the severe floods of 2003 washed out bridges and parts of the Suiattle River Road, the tribe has been keeping a close eye on the rivers from which they get their name.
In the 2003 flood, the river gauge recorded a peak flow of 106,000 cubic feet per second.
“That got everyone’s attention,” Morris said.
The tribe installed a logjam at the mouth of the slough, and so far it — plus lower levels of flooding since 2003 and maybe a little luck as well — has prevented the catastrophe that would occur if the river spilled back into the slough.
The logjam is only a stopgap solution, however.
“It will never keep the river out of that channel, but in big flows it will slow it down,” Morris said.
Lahars from Glacier Peak’s last major eruption 12,000 years ago diverted the Sauk River from the Stillaguamish watershed so that it now empties into the Skagit River to the north.
The Sauk carved out its 4,000-foot-wide channel between those volcanic deposits, its course shifting in the easily erodible sandy sediments that fill the valley.
The Sauk-Suiattle reservation is built on one such sedimentary shelf, and its elevation is only about four feet above that of the river.
A warming climate will only exacerbate what was already a worrisome, if natural, process.
“Other than the channel migration, we noticed more migration of the river, and with high water it moves closer to the reservation,” said Jason Joseph, the tribe’s natural resources director.
The Army Corps of Engineers developed an emergency plan for the reservation in case there were another flood like the 2003 event, Lenon said.
That plan would call for excavating the area near Reservation Slough, filling it with rock, then covering it over with soil to create an artificial dike.
It might protect Chief Brown Lane, the loop road on the reservation, but eight houses on the eastern edge of the reservation would have to be moved or demolished.
Even then, “there’s no guarantee it would work,” Lenon said.
For Lenon, who volunteers with the Stillaguamish Water Rescue Team, the need to move the reservation was hammered home during the response to the Oso mudslide.
There is a 30-foot-high knoll below the slide that effectively split the mudflow on the valley floor, Lenon said.
“I noticed that hill that divided the slide was the difference between life and death,” he said.
The tribe bought the 40-acre Allen Gravel Pit property west of Darrington in June for about $150,000.
Lenon would like to move all the reservation buildings to the new land, which is about 40 feet above the level.
Other tribes have moved their reservations in recent history. On the Olympic Peninsula, the Hoh and Quileute tribes have both moved or are moving away from the coast to higher ground to avoid the threat of flooding and tsunamis.
Native Alaskan tribes have also been looking to relocate as climate change has caused increased flooding, erosion and accelerated loss of sea ice and melting permafrost underneath their villages.
But relocation is an expensive undertaking, and the Sauk-Suiattle tribe doesn’t have the resources larger tribes like the Tulalips have. The Sauk-Suiattle tribe has about 225 members, with about 20 homes on the reservation. There are another 10 families which still need housing, Lenon said.
But he estimated that it would cost $3.3 million just to lay in the road to the new site and install infrastructure.
Lenon plans to apply for federal grant money to help offset some of the costs. Otherwise, the plan is to work on the relocation one piece at a time.
“At that pace it might be 10 years before we can be moved,” Lenon said.
He’s hopeful Obama will be sympathetic to the tribe’s cause, especially after the president’s visit to Oso after the slide.
“I think he can understand our concerns since he’s been here,” Lenon said.
Chris Winters: 425-374-4165; cwinters@heraldnet.com. Twitter: @Chris_At_Herald.
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