New Life for the Elwah

Remnants of early morning fog along the Elwah River

In 1910, the Elwah River on the Olympic Peninsula in Washington State underwent some changes. Big changes. Power was needed to support the burgeoning timber industry in and around Port Angeles, WA. A dam would be built. A 108 foot high dam that would transform the river upstream of it from from a wild, roaring river teeming with five different species of native salmon, into a flat and placid reservoir, filled not with salmon but with sediment. With no fish ladders, these salmon would be denied access to their spawning grounds upriver by a massive concrete block known as the Elwah Dam. Within a few decades, any fish that managed to miraculously jump over the 108 foot high dam would have a second nasty surprise waiting for them just a few miles further upstream, the 210 foot high Glines Canyon Dam, built in 1927.

Sunset over the Elwah Valley from Highway 101, just west of Port Angeles, WA

Fast forward nearly a century, and big changes are occurring yet again.  In just a few short months, these two barriers will have been completely and permanently removed and the Elwah River will once again flow, uninterrupted, from the permanent snowfields and glacier of the Olympic Mountains all the down to sea level and the Strait of Juan de Fuca. Even now (June 2013), only a small remaining stub of Glines Canyon Dam is preventing the salmon from moving back up into their traditional spawning grounds, and nearly 24 million cubic yards of sediment  trapped behind the dams from moving down to the river’s mouth. To give you a sense of just how much material that is, 24 million cubic yards would be enough to bury an American football field under so much sediment that not even seven Empire State Buildings stacked on top of each other would reach the top of the pile. While numerous dams have been decommissioned and removed around the world over the past several decades, none have been as large as Elwah and Glines Canyon. Nor have any been as controversial, as indicated by the fact that Congress passed legislation to remove the dams in 1992, yet demolition did not begin until 2011.

The former site of the Elwah Dam, now occupied again by the free-flowing channel of the Elwah River

Groundwater containing dissolved iron was trapped beneath the reservoir for decades. With the reservoir gone, this water can escape and the iron rapidly oxidizes as it is exposed to oxygen in the air. 

Controversy aside, it is not often that one gets the opportunity to walk along the bottom of a reservoir without fear of drowning. As removal of the two dams enters its final stages, there exists a fantastic opportunity to watch an entire ecosystem attempt to return to its natural state. I visited the Elwah River valley on a cloudy, yet pleasant by Olympic Peninsula standards, weekend in May to see the effects of dam removal first hand. My first stop was the former site of Lake Aldwell, the narrow, yet shallow reservoir, 4 km long and 30 meters deep, that once existed behind the Elwah Dam. Lake Aldwell was the lower of two reservoirs on the Elwah (the other being Lake Mills behind Glines Canyon Dam), just five miles upstream from where the river ends its 45-mile long journey from the mountains to the sea.  It was also the first to be drained, in 2011, and consequently has already had an entire growing season to begin recovering from over a century of submersion. Assisted by planting efforts, so far, “recovery” consists of some small alders, grasses, and a handful of wildflowers that have taken root in the layers of extremely fine grained sediment that accumulated on the bottom of the reservoir from 1910 to 2011.

Prior to the construction of the dams, the Elwah River valley contained spectacular old growth forests, the proof of which can once again be seen today. It is is the stumps of these gargantuan trees that are perhaps the most impressive sight at Lake Aldwell. Giant cedar stumps, the result of early 20th century loggers who were understandably eager to harvest the enormous trees on land slated for inundation, have been exposed as the river rapidly washes away the layer-cake of sediment that  piled up at the bottom of Lake Aldwell. The size of the stumps are humbling and they are shockingly well preserved; many of them still contain the deep, horizontal notches cut for logger’s springboards, some so fresh in their appearance that it’s hard to believe that they weren’t felled just a few years ago, a testament to the preservation power of the meters of silt and dozens of meters of water that covered them for a century.

Giant Cedar stumps on the floor of Lake Aldwell. The former level of the reservoir can be clearly seen on the far bank.

Century old stumps are joined by new vegetation just beginning to take root in the lakebed sediments.

A stump that has been only partially exhumed from the sediment, with the six-foot tall photographer for scale.

The most powerful location from which to contemplate the restoration of the river is undoubtedly the site of the former Lake Mills.  Unlike Lake Aldwell which is located right along US Hwy 101, Lake Mills requires a little bit of effort to get to. Located within the confines of Olympic National Park, the head of the now drained reservoir is reached only by driving up a narrow, one lane dirt road that winds through the rainforests of the Olympic Peninsula several hundred feet above the course of the Elwah. Near the end of this road, a narrow footpath leads down to what was once the lake’s edge.

Being the uppermost of the two reservoirs, Lake Mills was where nearly a centuries worth of sediment accrued, scoured out of the Olympic Mountains just as it had been for thousands of years, by storm after storm after storm blowing in off the Pacific, dousing the mountains in rain, and sweeping the sediment into rivulets, tributary creeks and streams, and eventually the cold, swift, and turbulent Elwah. Once Glines Canyon Dam was built in 1927, the whole system just shut off. Vast quantities of silt, sand, and gravel sediment that would normally create a delta at the mouth of the river began creating a delta in Lake Mills instead.

Immediately upon breaking out of the trees, one is taken aback by the sense that something drastic has happened here. Over a thousand vertical feet of dense, dark green, damp forest immediately transitions to a landscape that looks like it belongs on Mercury or the Moon rather than the lush Olympic Peninsula. One is greeted by a staircase of spectacular gravel terraces leading down to the river’s edge, terraces cut by a river eager to make up for 100 years of lost time. The river’s path is changing on a near daily basis as it cuts down through the canyons of sediment. The only sound that accompanies the roar of the river is the constant and somewhat unsettling sound of miniature rockfalls breaking loose and sending pebbles, cobbles, and sometimes boulders scurrying down slope, the sounds of a landscape still changing by the minute as the river tries to re-establish its old course through the valley.

Terraces carved out of delta sediments by the resurrected Elwah River as it runs through the valley formerly occupied by Lake Mills.

The erosive power of the Elwah can be seen just by observing its color as it runs through its former delta. When the river first exits the confining gorge of Rica Canyon and explodes out into the wide valley once occupied by Lake Mills, it shines with a brilliant aquamarine color, almost tropical in its hue, due to the presence of extremely fine grained sediment suspended in the river. The river does not retain this color for long though. For decades, any coarse sediment brought here by the river would be abruptly dropped at the entrance to Lake Mills, as the energy level of the river dropped precipitously entering the tranquil reservoir. Now, with the reservoir gone, all that sediment is there for the taking and the river quickly takes full advantage. Just a few hundred yards later, the river has turned the color of a late-afternoon summer thunderstorm, a deep and foreboding dark gray, as the Elwah picks up coarse sediment and begins moving it downstream where it naturally belongs.

While the dams may be gone, and the fish have already shown signs of returning, the story of the Elwah is, in reality, just beginning. All the effects, both positive and negative, of such a large scale experiment won’t be known for many decades. I encourage you to go see it for yourself; as I mentioned earlier, opportunities to experience a landscape changing at such a rapid rate are rare, much less one in as spectacular of a setting as the Elwah River.

More information about the Elwah River Restoration project can be found here.  To get a better idea of the changes that have occurred so far, I strongly recommend checking out slideshows and time-lapse videos made from a series of webcams that have been monitoring the progress here.