Until now, Matt May and Rachel Halstrom have been driving to walk.

They've been hopping in their car for the 10-minute jaunt to the nearest regional park, where there are trails curving through lovely forests.

So they are pretty psyched to have one about to open alongside their own neighborhood in Prior Lake. Psyched enough to be out using it one afternoon last week before it was marked out to passing motorists, or even, frankly, open for business at all.

"We're not going to get yelled at, are we?" May asked, peering at the park workers installing some of the scores of signs that mark out the trails.

More important is the sense that a remarkable transformation has taken place on a piece of land that has been waiting to become a real park for more than 40 years -- and in the meantime was among other things a refuge for the homeless.

"We love this place," said Halstrom. "There's a new and different view around every corner. And we walk a lot more now."

This weekend marks the formal opening of phase one of Spring Lake Regional Park, the latest of the metro area's major destination parks.

That sort of park is aimed precisely at the type of user who will go out of his or her way to enjoy acreage that is much bigger than a typical neighborhood park.

Three miles of smooth, brand-new bike trails lace through woods and open oak savannahs.

Perhaps the most remarkable thing about this project has been the removal of a long segment of an entire county road that once crossed through. It has now become so artfully a part of the trail system that even people who knew the area well might find themselves straining to remember where the road used to be.

Tipoff: The open area is a lot wider than most trail segments, with erosion matting that is allowing for the growth of native plants. Your brain thinks, "Why is this so wide? Why did they knock down all these trees?" But they didn't. They shrank the old roadway down, and in time it will look even more natural.

The park has been created as part of the new partnership with suburban Hennepin County's Three Rivers Parks system, which means that a system with an infrastructure almost laughably more rich than Scott County's is at work creating it.

Case in point: Erin McClenahan was out the other day with her GPS tracker, documenting the precise location of such things as underground electrical lines and overhead lighting around the gravel parking lot alongside the new off-leash dog park, with its restrooms and its watering device for dogs, which looks like a drinking fountain for dolls, way down by the ground.

McClenahan's job is mapping things for the parks system. Contrast that with Scott County, which has two people in its entire parks department and borrowed highway engineers to oversee the trail creation.

As Three Rivers maintenance supervisor Brad Chock gave a tour of the extensive system of trails -- some wooded and shady, others around open fields with long views toward Prior Lake and the sparkling waters of Spring Lake -- it became apparent that it will be tricky to situate yourself. There are lots of turns, lots of forks in the road. How is one not to get lost?

"You can get maps online and print them out on our website," he said, "and there will be maps on signs in different places to show you where you are."

May and Halstrom were pleased to hear that the trails they were using amid brilliant fall colors will be plowed in the winter for year-round use.

And another hiker asked about the off-leash dog area -- 10 acres, or about a third the size of the one at Cleary Lake Park, but prettily organized and far from just a big soulless piece of turf. It's fenced and has a separate small-pet area, vault restrooms, drinking water and a dog-washing area.

One thing that will make bikers cringe is the dry gravel road leading up to the park off of County Road 82 near Mystic Lake Casino, which will coat gears with a layer of dust and grit.

The road isn't being paved because it isn't the permanent park entrance, said Scott County's parks and trails chief, Mark Themig.

"We want to bring people in from the west, ultimately," he said, rather than the north. "But that will depend on future development."

It's only one phase and may seem a bit incomplete, though it still does represent a major move forward for a county that has taken its time to develop a park system.

"People were getting impatient, and rightly so," said Scott County Board Chairman Tom Wolf. "We bought land for parks in various places, yet we weren't opening them as parks."

True enough, said Boe Carlson, associate superintendant for parks and trails at Three Rivers, but progress is now being made.

"Cedar Lake Farm is online, Spring Lake is coming online, there's potential for Doyle and Blakely [two sites in now-rural areas] as time goes on," he said. "The growth of this system in a relatively short period of time has been wonderful."

Themig is especially fond of one feature: a huge flat stone along a line of boulders in a retaining wall that just turned up that way naturally and becomes a bench that's a viewing point for a wetland. "I hope people will find it," he said. "It's not totally obvious that it's even there."

David Peterson • 952-746-3285