Keeping Their Spirit Up Lake Residents Haven’t Given Up On Plugging Their Leaking Mill Pond

Where sneakers and shovels fail, tractors will prevail.

At least, that’s the theory.

After two unsuccessful campaigns to halt the leaks in Spirit Lake’s “mill pond,” property owners plan a third assault this summer. This time, they want to use heavy machinery to plough and compact the lake bed, squashing shut the leaks.

“If we can’t, then there’s going to be some dry wetlands and some devalued property,” said Jerry Peterson, president of the Spirit Lake Homeowners’ Association.

“We’ve stopped some of the leakage, but the water finds the weak spots and channels down,” he said.

The group wants to dam the 54-acre mill pond in June, let it drain and then begin the work.

Jim Brady, a navigable waters specialist with the Idaho Department of Lands, said the group will likely receive the needed permits. The homeowners’ group is also seeking a grant to pay for the $30,000 project.

The leaks, according to geologists, result from the lake’s unusual structure.

Most lakes, including Coeur d’Alene and Hayden lakes, intersect with the underground aquifer.

But Spirit Lake is a so-called “perched clay-sealed bottom lake,” Brady said. In layman’s terms, that means it’s essentially a clay bathtub sitting atop dry gravel. The aquifer is actually 200 feet below the lake.

“I think there are only a couple dozen perched clay-sealed bottom lakes in the United States,” Brady said.

After several years of drought, the mill pond dried up in 1993. The exposed clay baked in the sun, shrank - and cracked. The leaks began.

There were other leaks, too, due to old pilings and bottom-scouring by the tugboats of the former lumber mill that gave the pond its name.

The largest documented hole, Brady said, was more than 5 feet in diameter, with rocks and debris in the bottom. It took 50 50-pound bags of clay and 2 cubic yards of gravel to fill it.

So, if Spirit Lake is a bathtub, the mill pond is the drain. Measurements taken by the Idaho Department of Water Resources in May 1995 showed that the mill pond was leaking 493 gallons of lake water per second.

Not surprisingly, the phenomenon alarms people whose lakeside property, during summer, now overlooks mud flats. Some have written to Gov. Phil Batt, demanding that the state fix the lake.

Others tried to fix the leaks on their own. Fireside Inn owner Rod Erickson, whose lodge sits on the banks of the mill pond, mapped dozens of holes in the lake bed. He and a handful of volunteers floated barges to the leaks, then packed in gravel and clay to seal them off. In many cases, it worked. But several of the holes reappeared.

Last summer, about 50 volunteers donned old sneakers and tromped in a line around the lake, attempting to squish the lake mud down and seal the smaller holes.

But the “sneaker stomp” was too little, too late, Brady said.

“If they had three waves of 150 people, it might’ve worked,” he said.

The homeowners’ association hired Golder and Associates, a Redmond, Wash., engineering firm, to design a solution. The $1,700 study recommends damming the mill pond’s inlet and letting the pond dry.

Then, Brady said, workers would go in and remove logs resting in the mud. Farm equipment would disc the lake bed, cutting up the clay so it will better soak up the fall rains and expand.

Other machinery, meanwhile, would squash the clay to a tight seal.

Peterson said mill pond homeowners seem willing to put up with a summer of dry lake bed in order to fix the leaks. The pond would likely be dry by mid-summer anyway, he said.

“They would much rather put up with no water for a little time and get it fixed,” he said. “They’ve got everything to gain and nothing to lose.”

Brady said the project wouldn’t kill many fish, which tend to head to the lake’s deeper water when the mill pond gets low. The area is a popular fishing spot for bass and perch.

“There may be some sacrifice. I don’t think it’ll be anything significant,” Brady said. The logs would be put back afterward to provide fish habitat, he said.

Brady and other experts believe the lake bed, given enough water, would eventually swell up and seal itself. But it takes a long time for water to penetrate the clay, layer by layer, Brady said.

“They said this may cure itself, but it could take from 2 to 200 years,” said Peterson.

“This is not something we want to sit around and wait for.”

, DataTimes ILLUSTRATION: Color Photo Graphic: Why is mill pond leaking?