Williamson River Delta Explosions and Restoration Q&A

Breech Event Map

See where levees were places and what flooded.

Lost River Sucker

Endangered fish species in Upper Klamath Lake

"The recipe for restoring wetlands has one main step: Add water."

Mark Stern, director of the Conservancy’s Klamath Basin Conservation Area

In a move to reverse the fate of two endangered fish species and to benefit other wildlife, the Conservancy used 100 tons of explosives to breach two miles of levees along Upper Klamath Lake in late 2007. Removing the levees is part of a larger project to restore the vast marsh wetlands that once dominated the Williamson River Delta.

Nature.org caught up with Mark Stern, director of The Nature Conservancy’s Klamath Basin program, to talk about this unprecedented effort and  how explosives may bring back two species of fish from the brink.

Nature.org: Conservationists aren’t exactly known for their use of explosives. Why is the Conservancy blowing up a bunch of levees?

Mark Stern: The recipe for restoring wetlands has one main step: Add water.

The restoration project at the Williamson River Delta Preserve — one of the largest projects of its kind ever in Oregon — first involved moving more than 2 million cubic yards of soil and then, working with engineers, preparing levees for the blasts.

We determined that the best way to remove the levees quickly and safely was to use explosives to destroy two miles of levees in a matter of minutes. Once the levees were breached, waters from the Upper Klamath and Agency Lakes immediately inundated the site, covering about 2,500 to 3,000 acres with water — as much as six feet in some places.

In the years that followed, we continued restoration at the site, removing levees without explosives and reconnecting historic wetlands. Now the entire detla is flooded.

Nature.org: Is this a common practice in conservation?

Mark Stern: Restoring wetlands is occurring throughout all regions of the world, and I’m sure that many innovative techniques are used. While I imagine explosives are used in some situations, I think it’s safe to say there haven’t been many projects where explosives have been used at this scale.

Nature.org: What does preserve look like after the levees were breached?

Mark Stern: The levees were breached in October of 2007. Quite simply, what used to be land is now water. And watching the explosives? It was an incredible site to see.

Nature.org: Earlier you mentioned that the two endangered species — the shortnose sucker and the Lost River sucker — will benefit from the wetlands restoration project. How so?

Mark Stern: Adult suckers live primarily in Upper Klamath Lake for most of the year — but they migrate upstream in early spring to spawn. Before the area was turned into farmland, larval fish would flow downstream and hang out in the marshlands at the mouth of the river until they were large enough to enter the lake.

When this protected rearing habitat disappeared, the larval fish began emptying directly into the lake. Without time to gain size and strength in a safe environment, the young fish had a hard time surviving. So this project will provide much-needed marsh habitat for young fish. It’s important to recognize that these are long-lived species. Most don’t begin to spawn until five or six years of age, and adults may live to 40 years. It will take time to fully recover these species, but we are encouraged by the results we’ve seen so far.

And the restored wetlands will also be great habitat for birds and other wildlife and will help improve water quality in Upper Klamath Lake.


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