Back in the day, Wood Lake was just a regular city lake, the kind of place where neighbors gathered to sail, swim or fish for sunnies. But the post-war building boom that rolled across Richfield cut off the underground springs that fed it, reducing the modest lake to a waterlogged meadow.

The boggy, 150-acre site just off Interstate 35W was considered and rejected as a golf course, considered and rejected as a community college campus. It wasn't until 1971 that the amalgam of cattail marshes, woodlands and prairies came into its own as Wood Lake Nature Center.

Now birders flock to the teeming marshlands, which serve as a wayside rest for migrating scarlet tanagers, American redstarts and a dozen kinds of ducks. Wildlife lovers watch baby muskrats skim across the murky water to hide among the bulrushes. And on hot summer days, kids from the day camp at the interpretive center race along the wooded trail in search of toads.

Eventually, they'll reach a weathered floating walkway that stretches across the marsh. With their first bouncing steps, they can grab for the cable railing, realizing that they're walking on water.

"Some of the city kids compare it to a ride at Valleyfair," said Karen Shragg, a Wood Lake naturalist.

If you prefer more stable footing, take the 3 miles of wheelchair-accessible crushed-limestone trails that meander through the woodlands, with their demure Virginia waterleafs, and the restored prairies that pop with flat-faced sunflowers and black-eyed Susans.

That's where Helen and Gordon Carlson come to power-walk. "We came to see the wild roses blooming," said Helen. "And feed the mosquitoes," added Gordon.

The Carlsons live just down the street in a high-rise surrounded by restaurants and strip malls. But when you're in the middle of the nature center, waiting for a painted turtle to emerge from the cattails, you forget that Richfield -- and the rest of the world -- is just outside the gate.