Getting to the bottom of lakes

Packing a full tank of oxygen, Arline Fullerton snaps her mask into place and plunges into the fresh waters of Pipe Lake.

The 68-acre lake, which straddles the border of Maple Valley and Covington, isn't a place most would choose to find underwater scenery.

Fullerton, a scientific diver, hopes to find nothing at all as she spends two days combing the lake bed for hydrilla, a slimy green weed that infested Pipe Lake and adjoining Lake Lucerne.

The lakes have the only known incidence of the invasive weed in the Pacific Northwest.

"Is this the year I was supposed to bring champagne?" Fullerton said, joking, hopeful that the second day of diving in the lakes will show no sign of hydrilla, which will be cause for celebration.

In Southeast King County — where more than 30 lakes are squeezed by people, houses and all the typical signs of growth — keeping these bodies of water clean and safe can be a challenge.

"The area's urban center is growing rapidly, from the perspective of aquatic ecosystems, there's a lot of environmental degradation that comes with development," said Daniel Schindler, a University of Washington professor of aquatic and fishery sciences who has studied the area's small lakes.

The obvious enemies of area lakes are exotic plants — hydrilla, fragrant water lilies common in ponds and Eurasian watermilfoil — known to take over lakes. But less noticeable pollutants come from storm water, septic fields and destruction of trees.

King County water specialists say that every lake in the county is fit for swimming, but Schindler says that could still mean that many are in trouble. Few small lakes in King County are thriving, he said.

Many residents who flock to waterfront homes are unaware of how their behavior affects a lake's ecosystem. Some practice eco-friendly habits — washing cars on their lawns, limiting use of fertilizers and leaving lake beds alone — but many make poor choices that have lasting consequences for lakes.

"We all live on watersheds," said Sally Abella, manager of King County's Lake Stewardship Program. "The real story is that people's actions matter."

Scientists believe hydrilla in Pipe and Lucerne lakes likely came either from an aquarium dumped in the lakes (a plant once common in fish tanks) or from a stray plant attached to an exotic lily.

Crews of divers and researchers have worked for 14 years to eliminate the weed and prevent it from spreading to other lakes. The state Department of Ecology has paid the majority of the $100,000 annual cost of the program. Maple Valley and Covington split the rest of the cost.

The lake is one of 43 monitored by the King County Lake Stewardship Program.

Under the stewardship program, resident volunteers become lake stewards, who take samples from small lakes that are sent to a lab for analysis. The county tracks the data but because of budget cuts, it maintains lakes only when cities or government grants pay for it, Abella said.

Some residents say the county should do more for small lakes, especially in unincorporated King County.

Valarie Matinjussi, a homeowner in the Panther Lake area, says she is frustrated by the county's lack of oversite of Panther Lake, which has not been monitored for several years.

Matinjussi and her neighbors say the 31-acre lake has become overgrown with exotic lilies, which have crowded out native plants and made it difficult to navigate even a small canoe through the water. They say it is the county's job to fix the matter.

But officials say a limited budget restricts what the county can do for the lake, Abella said.

It would be too expensive to monitor and maintain every lake in King County, she said.

From Matinjussi's backyard, Panther Lake's water level is visibly lower than it used to be, and the lake smells rotten.

"Would you want to swim in this?" said Matinjussi, who used to regularly swim in the lake.

Residents suspect that runoff from nearby developments could be damaging the lake, but because no long-term water-quality data is available, no one know what the problems are.

Finding solutions can be complicated. Many lakes have natural cycles and it's hard to tell whether a lake is unhealthy or undergoing a natural change.

Some lawmakers would say that the best way to promote health in large lakes is to create policies that support them. Many point to Lake Washington as an example.

Some 50 years ago, sewage from nearby suburbs filled the lake, it was considered too polluted to swim in. It took the creation of King County Metro Council to develop a sewer system that would divert runoff and clean up the lake.

At Pipe and Lucerne lakes, though, scientists have worked diligently to eradicate the hydrilla.

Fullerton ends her dive with good news: After two days of diving, she came up empty-handed.

There was no champagne, however: The lake will need to be hydrilla-free for five more years before the celebrating begins.

Karen Johnson: 253-234-8605 or karenjohnson@seattletimes.com