By Jen Newlin Bell

A few weeks ago, Nature Conservancy scientist Mark Stern decided to go swimming. That’s not far fetched for a wetlands specialist — except that this swimming hole was, until recently, a dry field.

In October 2007, the Conservancy used around 100 tons of carefully placed explosives to breach four levees — each a half-mile in length — and successfully flood about five square miles of the Conservancy's Williamson River Delta Preserve along Oregon’s Upper Klamath Lake.

The point of this unprecedented conservation strategy? To restore historic wetlands and benefit water quality, wildlife and two endangered fish species. Recent restoration work is already paying off:

• Around 3,500 acres are now flooded. It took two years to prep the site and move enough dirt (about 1.75 million cubic yards, or 175,000 dump truck loads) for a successful flood that best matched modeling for historical conditions.
   
• Larval fish — including the Lost River and shortnose suckers, two endangered fish species — are already being found in newly restored areas.
   
• Wetland plants such as tules are emerging. Although the area was converted to farmland, historic seed banks of wetland plants were waiting. This summer, when lake levels naturally recede, more plants will begin to germinate.

Today, it's hard to tell that this sun-speckled surface of blue was ever farmland. Stern — the Conservancy’s Klamath Basin conservation director — now has a hard time getting his bearings on the preserve. Old landmarks are several feet below the surface.

Why Blasting Was the Best Route

The Williamson River Delta was historically a vast expanse of marsh and lake-fringe habitat. As industry began to crescendo in the early 1950s, levees were constructed and the delta was converted to farmland. 

In the 1990s, stakeholders identified restoration of these wetlands as an important ecological step in the region. So the Conservancy and its partners began to acquire over 11 square miles and started work on the $10 million project — removing levees and restoring the water.

Because some soils were unstable and the lake level was higher outside than the land inside, demolition by carefully calibrated explosives was deemed the best alternative for removing key levees.

Letting Nature Finish the Work

At dawn one October morning, engineers in hard hats combed blast zones one last time. Boats patrolled and helicopters hovered. Nearly 200 people attended the event, corralled by orange fencing a safe distance from explosives.

There were four blasts, each lasting about five seconds. Debris shot 300 feet in the air. A roar like fireworks followed. And the water returned.

Immediately following the blasts, teams returned in boats to begin assessing results. But winter came quickly.

“Really, it was time to wait," Stern says. "We just set the stage for nature — in the form of ice, wind and water — to finish the work. Then we’d see what happened when the lake was at full pool in the spring.”

Wildlife and Scientists in Full Swing

Heather Hendrixson’s first flight over the preserve (after the ice thawed) wasn’t from the small prop plane, but a commercial flight. Hendrixson, the new preserve director, made sure to get a window seat. 

“It’s really amazing to see it for yourself, having seen the fields before,” says Hendrixson. “It looks like it’s always been wetlands.”

In spring, the lake level is high and adult suckers spawn in the Williamson River. This time of year, larval fish drift downstream into the restored marsh at the preserve. The new wetlands will provide a haven for larval suckers, protecting the fish at a critical life stage.

And science is in full swing, too: Conservancy scientists and partners are surveying fish population density and distributions and monitoring water quality on a daily basis. They trek into the marsh in chest-high waders and set nets for the suckers.

Field-work gear for monitoring would make the gadget-saavy swoon:

• Black, slender data recorders take hourly readings on water quality. Ecologists boat out and download information directly onto palm-held computers.
   
• “Grab sampling” done at 27 sites involves taking surface water samples with a wide, clear tube fitted with plungers.
   
• In the lab, water samples are analyzed for almost a dozen constituents including carbon, nitrogen and phosphorus.

'Seeing It — Whoa'

Scientists have been monitoring the lake’s water quality for years, and they hope the new wetlands will make a positive change. 

Wetlands are natural filters (nature’s kidney, if you will). At the preserve, wetland plants are already beginning to emerge, though they’ll take several years to fully re-establish.

Meanwhile, Klamath staffers are absorbed in data collection and new restoration work on the other half of the preserve (without the use of explosives). And, occasionally, Stern goes swimming.

That particular day, he boated out to the first blast zone and jumped in. When he tried to touch the bottom, the water was over his head.

“We’re really pleased with the way it looks and it’s what we anticipated,” Stern says. “Intellectually, you know what it’s going to look like when it’s flooded. But seeing it — whoa. That’s a huge change. This will be wetlands as far in the future as anyone can imagine, I think.”

Jen Newlin Bell is a writer and graphic designer for The Nature Conservancy.

Nature picture credits (top to bottom, left to right): Photo © Scott Nelson (Williamson River Delta Preserve, before demolition); Photo © Charlie Erdman/TNC (Williamson River Delta Preserve after the levee detonations); Video © TNC; Photo © Larry Turner (Mark Stern, the Conservancy's conservation director for the Klamath Basin); Photo © Siana Wong (Carolyn Doehring, restoration steward, collecting samples for water quality work)