Renton bog reaches 5,000 years into past

RENTON — The pattern and purposefulness of a sphagnum moss bog's diminutive hills call to mind nature sculpture by artist Andrew Goldsworthy. But the only thing human beings have to do with the appearance of this 5,000-plus-year-old wetland is protecting our ability to experience it in its wild state.

Called hummocks, the mossy formations are mostly the result of natural settling in the centuries-old decomposing plant matter below.

"People say they can breathe easier here," said Max Prinsen, surveying the spongy green world from a boardwalk at Shadow Lake Bog, next to his Renton home. The summer heat was lessened by the quiet efforts of the mosses, waxy-leaved bog plants and a mix of Sitka spruce, cedars and firs — their intermingled scents a cooling aromatherapy. As co-founders of a group called Save Habitat and Diversity of Wetlands (SHADOW), Prinsen and his wife, Erin Wojewodzki-Prinsen, have devoted much of the past 10 years to preserving this rare wetland area, and educating people about it.

They spearheaded building of the boardwalk so the public could safely visit the bog at times such as an annual festival, which happens this weekend. Prinsen, who studied forestry in college and now is a manager for Otis Elevator, points out to visitors interesting bog facts easily overlooked by untutored eyes.

"Notice anything different about that tree over there? Those twists and turns in the trunk show it's much older than it looks." Only 5 inches in diameter, the gnarly bonsai-esque hemlock was perhaps 80 years old, Prinsen guessed. In sphagnum moss bogs, the highly acidic environment fosters unusual plants while stunting the growth of others. Plants that thrive here include the fly-hungry round-leaved sundew — one of Washington's only native insectivorous plants.

Slow decomposition

Frog Frolic

Event this weekend

Shadow Lake Bog Frog Frolic is 1-5 p.m. Sunday. Come to this annual celebration to get to know the bog, its inhabitants and its advocates. The public is welcome for bog tours, music and theater performances, a raffle and silent auction. Beverages and cake will be provided. Bring a potluck dish to share. For more information: 425-432-9965.

Getting there

Shadow Lake Bog is located at 21818 184th Ave. S.E. in Renton. From Interstate 405 take the Maple Valley/Enumclaw Exit (Highway 169) to 140th Avenue Southeast. Turn right. At the fourth stoplight, turn left on Petrovitsky. Travel east for 3.3 miles to Southeast Lake Youngs Road, and turn right. Drive the equivalent of one big city block to 184th Avenue Southeast and turn right. Continue for a little more than one mile to the bog entrance. Driveway is on the left. Park on 184th.

Visiting at other times

The public is welcome to visit Shadow Lake Bog, but please call first: 425-432-9965. School field trips on water quality, bog function and preservation have been designed to meet state education requirements for grades three-12. For more information, call the number above. Volunteers are welcome.

Noticing and responding to details is one of Prinsen's strong points and part of what attracted him to this place in the 1970s.

"We started looking closely at this wetland system and discovered how truly unique it is," he explained. "We realized that if the hydrology changed it could go away. Our mission has been to keep that from happening."

It took 18 years to acquire the bog and another 10 to remove tons of trash, restore the land, renovate an existing structure to become a learning center and identify and purchase adjacent land, while creating a strong network of support.

Adjacent to Shadow Lake, the bog was formed when a retreating glacier left a bowl-like impression in the landscape. Little water flows into or out of this natural container, inviting the growth of sphagnum mosses that release tannins and acids, making the water low in oxygen and slowing decomposition. Peat is an organic soil that develops where plants grow more quickly than they can decay. Year after year dead sphagnum mosses pile up. Compressed by the weight of decades of growth, these partially or incompletely decomposed plants form peat. This bog's 45 to 65 feet of peat took an estimated 5,000 years to accumulate.

In King County less than 3 percent of sphagnum moss peatlands remain. Historically, the rich peat was mined for use in agriculture and the land was dismissed as useless "swampland" and filled in for development. And we can't bring peatlands back.

"It's not possible for man to create these kinds of wetlands because the plants and the chemistry in them are not reproducible," said Sarah Cooke, a Seattle-based wetland ecologist and author of books on the subject. "We can recreate even old-growth forests if we wait many years, but we cannot establish the chemistry which occurs in bogs."

Giant sponge

Like other wetlands, bogs help prevent flooding and provide habitat for birds and animals. Their main ecological function is to act as a giant sponge, helping to hold groundwater. On a larger scale, peatlands deter global warming by storing massive amounts of carbon. Bogs are a kind of living museum for scientists who find buried biological treasures in their peat stores.

"The acidic environment acts as a preservative, and basically pickles things," explained Prinsen.

In Ireland a bog-preserved antler stretching 12 feet across is the only evidence a giant elk once roamed there. An 11,000-year-old mastodon unearthed in the peaty underworld of an Ohio golf course harbored ancient living bacteria. And in Denmark, a prehistoric gentleman was so unchanged by his peat entombment that 2,000 years later his chin still wore a 5 o'clock shadow.

At Shadow Lake bog, the creatures we encountered were thankfully still breathing: red-legged frogs and garter snakes.

"Because it's such a closed system, the bog provides a good opportunity to show cause and effect," said Bonnie Kallman, a K-8 teacher and SHADOW board member who has been shaping field-trip curricula to meet state education requirements. "Our programs work to engender a sense of stewardship."

Whether you're a human or a red-legged frog, your needs have been carefully considered here. It's evident everywhere, from a comfortable library with woodland views, to the stainless steel, no-skid layer on the boardwalk (aluminum treated with zinc is toxic to mosses). The attention to detail might inspire you to look at your own surroundings more closely — to find out what being a steward means in your own back yard.

Kathryn True, of Vashon Island, is co-author of "Nature in the City: Seattle" (The Mountaineers Books, 2003).