Follow us:

Field Notes

Covering the natural wonders of the Pacific Northwest

October 19, 2012 at 3:00 PM

Lake Mills on the Elwha is almost history

Since 1926, the glittering blue of Lake Mills has been a landmark — albeit an artificial one — of the Northwest landscape.

elwhateaserpic18 (2).jpg

Lake Mills, the reservoir behind Glines Canyon Dam, was actually at the root of the legal case to tear down the Elwha dams: the reservoir intruded into the boundary of Olympic National Park. While it still exists on maps and in the memories of many longtime Northwesterners, Lake Mills will soon be gone from the landscape.

Photo by Steve Ringman of the Seattle Times, taken October 1, 2010

Lake Mills has been steadily dropping since dam removal began on the river in September 2011. But, depending on weather over this weekend, it will be gone by next week. The lake is only about 8 to 10 feet deep at the deepest right now — down from 180 feet before workers began taking down the 210 foot tall dam, now only about 70 feet high.

Mills_20120927_Ortho_shrunk (3).jpg

Lake Mills is nearly gone. Andy Ritchie, Elwha restoration project hydrologist for the National Park Service took this aerial photo in September, 2012.

Photo courtesy, National Park Service

Here is the same view, one month later, photographed by Ritchie on Oct. 15, 2012. He predicts the lake will be completely gone by next week.

brighter.jpg

Lake Mills is nearly gone.

Photo by Andy Ritichie, Elwha restoration project hydrologist, National Park Service.

Courtesy, National Park Service

The dam might be completely gone by May. The schedule depends on the downstream effect of the massive amount of sediment about to be unleashed into the river. Slower is safer.

Less than five percent of the material pent up behind the dams since Elwha Dam was built in 1910 has been released, said Andy Ritchie, Elwha restoration project hydrologist with the National Park Service, based in Port Angeles.

Glines always hoarded the biggest load of sediment — and the two dams together trapped an estimated 24 million cubic yards of material –gravel, sand, cobble and fines that normally would have been rinsing down from the upper watershed, and distributed throughout the Elwha’s 45-mile length all the way to the saltwater Strait of Juan de Fuca.

One of the most important aspects of the $325 million Elwha restoration project is restarting the river’s capacity to transport that material, a natural process that shapes the river and provides habitat for everything in it.

The goal is to restart the conveyor belt without doing damage downstream. To control the release of sediment in to the middle and upper watershed, the sediment management team at the Denver office of the Bureau of Reclamation and locally in Port Angeles at the National Park Service have been carefully watching the pace of dam removal, so the river can keep up with its task of eroding out the material stuck behind the dams.

With the winter storm season getting underway, things are about to get exciting. A 70-foot wall of sediment has been advancing toward what’s left of the dam, and as workers continue to take it down, that material is going to start coming out.

Any day now, cobbles and sand are about to start tumbling over the dam — and that’s not been seen before.

“We’ve just seen the leading edge of the torrent of sediment, just a whisper of what’s to come,” Ritchie said.

Elwha Dam was completely gone by last March, but it didn’t have much big stuff behind it. The lower of the two dams, it trapped mostly sand and fines. It’s a different story with Glines, where a stockpile of gravel and cobble is on the way.

“What we are seeing is an increase in both the concentration and the size of what is coming,” Ritchie said. “The sand will speed down the river, the gravel will tumble, and the cobble will bump along. One of the big parts of this experiment is how the river will respond to sediment it hasn’t seen in 80 years.

“The coarse sediment part of this experiment is about to begin.”

Comments

COMMENTS

No personal attacks or insults, no hate speech, no profanity. Please keep the conversation civil and help us moderate this thread by reporting any abuse. See our Commenting FAQ.



The opinions expressed in reader comments are those of the author only, and do not reflect the opinions of The Seattle Times.


The Seattle Times

The door is closed, but it's not locked.

Take a minute to subscribe and continue to enjoy The Seattle Times for as little as 99 cents a week.

Subscription options ►

Already a subscriber?

We've got good news for you. Unlimited seattletimes.com content access is included with most subscriptions.

Subscriber login ►
The Seattle Times

To keep reading, you need a subscription upgrade.

We hope you have enjoyed your complimentary access. For unlimited seattletimes.com access, please upgrade your digital subscription.

Call customer service at 1.800.542.0820 for assistance with your upgrade or questions about your subscriber status.

The Seattle Times

To keep reading, you need a subscription.

We hope you have enjoyed your complimentary access. Subscribe now for unlimited access!

Subscription options ►

Already a subscriber?

We've got good news for you. Unlimited seattletimes.com content access is included with most subscriptions.

Activate Subscriber Account ►