the film

Oregon Project Reproduces
Lakes' Natural Flood Cycle

by Staff
Spokesman-Review, August 15, 2010

PORTLAND - Smith and Bybee lakes in north Portland have endured their share of indignities at the hand of man.

Construction of the Willamette and Columbia river dams usurped their seasonal rise and fall. The lakes spent decades in the leaching shadow of the city's garbage dump, the now-defunct St. John's landfill. A botched management attempt in the 1980s drowned much of the ancient ash forest that lined the lakes. Today, the lakes lie pinched by industry, port terminals and rail lines that filled and flattened much of the surrounding wetlands.

The humming warehouses and shipping centers along North Marine Drive are crucial to the regional economy. But if wildlife biologists and wetlands managers could turn back time and avert the damage to the lower Columbia's sloughs and marshes, they'd do it in a heartbeat.

Instead, in one small spot, they're trying the next best thing. Since 2003, specialists with Metro and other agencies and private groups have worked to re-create the flood-and-recede cycles that made Smith and Bybee a haven for birds, fish and native plants. The highlight is a 30-foot water-control structure, designed by the conservation group Ducks Unlimited, that holds water in the lakes during the winter and lets it go during summer.

"We put our finger on what the essential natural processes are and reproduce them, replicate them and try to restore them," said Elaine Stewart, senior natural resource scientist with Metro.

For eons, winter rains and spring snowmelt recharged the lakes and wetlands each year. Come summer and into fall, the water level dropped. A habitat developed that was suited to the cycle. Ash trees, for example, adapted to having their roots and lower trunks submerged for months at a time, and then drying out as the water crept away in the heat of summer. An earthen dam built in the 1980s turned the lakes into year-round bass ponds, and the constant high water killed hundreds of acres of ash forest before the mistake was realized.

The water-control structure has one-way gates that allow the Columbia's tidal rise to enter the lakes and that hold the winter rain. A fish ladder allows young fish to find off-channel shelter. At this time of year, workers remove boards at the top of the structure to allow the summer drawdown.

The system is imperfect mimicry, Stewart said. Problems persist, especially with invasive plants that threaten to choke a channel connecting the lakes, but eagles, egrets and herons hunt the shores and shallows. A survey showed juvenile steelhead, chinook and coho salmon in the lakes. Turtles, beaver, muskrats, coyotes and deer abound.

Over the past 15 years, workers have replanted 100 acres of native vegetation. Portland's Bureau of Environmental Services "gets credit for some of the best work out here," Stewart said, including planting ash trees 10 years ago.

The lakes and adjacent property, owned by Metro and collectively known as Smith and Bybee Wetlands Natural Area, cover 1,922 acres and may be the nation's largest urban wetland. It is safe from additional development because state law now specifically prohibits filling Smith and Bybee with dredging material.

The irony is that a distinctly wild place now thrives next to heavily developed industrial sites.

"In some ways, they're really good neighbors," Stewart said, leading a walk through chest-high grasses and pointing out healthy young ash trees. The commuting workers, trucks and trains come and go without venturing onto the wetlands, she says.

Other visitors, such as invasive plant species, are much more problematic. Purple loosestrife, the bane of temperate wetlands, has a strong root-hold at Smith and Bybee. Reed canary grass is a recurring problem. And Kevin O'Sullivan, a longtime supporter of the place, recently complained that new plants have clogged the lakes' connecting channel. In a July visit, he was unable to paddle through it and questioned whether Metro's water control structure works as it should.

"They've got it half right" by re-creating the winter floods, O'Sullivan said. "Now they're allowing the water to drop so low, it's giving these (invasive) plants a great opportunity to take over."

Stewart disagrees. "I think the structure is working as intended, but we're getting new problems," she said. "Every time we turn around we're getting a new invasive species to deal with."

The plants clogging the channel are from South America and prosper in water, she said. One is called parrot leaf; the other is a primrose with bright yellow flowers. At this point, manual removal is fruitless and might dislodge seeds that establish the plants elsewhere, Stewart said. She plans a herbicide attack in September, when the water is at its lowest and before the rain arrives. Herbicides will be selected with a keen eye to fish and bird safety.

"It's a matter of which problem to tackle," Stewart said.

Oregon Project Reproduces Lakes' Natural Flood Cycle
Spokesman-Review, August 15, 2010

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