The blur of purple-blue flowers began appearing in the roadside ditches as I sped toward my destination south of Olympia last May. I turned left off the pavement onto gravel, passed through the (usually locked) gate, drove up the road and parked in a huge field that already held several hundred cars.

I was at the Glacial Heritage Preserve, which protects prairies and oak woodlands that are among the rarest habitats in the state; less than 3 percent of Washington’s native prairies remain from those encountered by pioneers in the 1800s.

The preserve encompasses 1,020 acres of former cattle-grazing areas being restored to native prairies. Owned by Thurston County and the Washington Department of Fish and Wildlife, the land is now managed by the Center for Natural Lands Management.

It was Prairie Appreciation Day, the one day a year that the preserve is open to the public. This annual open house — happening May 10 this year — provides rare access to the preserve for everyone, not only to enjoy the land, but to learn about what it takes to restore a prairie. Luckily for me, last year’s event took place as the fields of blooming blue camas were at their peak. This native plant belonging to the lily family was prized by Native Americans for its small edible bulbs.

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“It’s an ecological preserve, but Prairie Appreciation Day lets people understand what’s being done out there,” said Kerry Hibdon, Thurston County Parks manager. “It’s a chance for people to ask questions and get an educated view of the property — and education is the greatest tool we have to gain a sense of stewardship.”

Don’t bug the bluebirds

I grabbed an orientation map at the welcome table and headed up the small hill on a gravel road. A sign cautioned against disturbing bluebirds in nearby nesting boxes. As I crested the hill, I saw clumps of visitors clustered around booths spread out along the road. Enthusiastic volunteers described prairie restoration efforts and the wildflowers and wildlife that live there.

The receding glaciers of the last ice age here dumped large gravel deposits that were colonized by prairie plants. Later, indigenous people burned the prairies to encourage the growth of food plants (including camas) and to attract deer and elk. However, once settlers of European origin arrived, they used the rocky land for cattle grazing and invasive plants soon took root. Starting in the 1990s, agency staff and volunteers have burned, mowed and dug out invasives — including thousands of giant Scotch broom plants more than 6 feet tall — to allow native plants to return.

Many booths had activities for kids, including the “pollinator station” where kids learned how bees pollinate plants.

“Educating kids helps them educate their parents. There are costumes for birds and butterflies that kids can wear, and they can dig for camas bulbs with pointed sticks like the Native Americans did,” said volunteer Kathy Whitlock.

At one booth visitors used a huge, weird tool to dig out invasive Scotch broom — not an activity that I imagined kids would find interesting. “Oh, kids love to do that,” said Whitlock.

Geology of mounds

Another station described the site’s geology, which includes unusual Mima mound formations (like those at nearby Mima Mounds Natural Area Preserve, which also has activities on Prairie Appreciation Day).

Visitors can spend time alone on the prairie by walking the self-guided, four-mile-long trail that runs along the perimeter of the preserve. A hayride that travels along a road parallel to the activity trail and through a Douglas fir forest offers easier sightseeing for the tired or less mobile.

“Older folks ride right along with the kids,” said Whitlock.

I shed my fleece jacket in the warmth of the sun and looked out over the acres of rolling landscape of wildflowers. I felt two states away from Seattle, instead of only two hours south.

“The feel of this property has to do with the large size of the preserve,” said Hibdon. “Sometimes when I’m out there I turn my truck off and just listen to the sounds of the insects and the birds. People need to see the preserve, and smell it, and feel it.”

Cathy McDonald is a freelance writer based in Renton.