For roughly 312 miles along Ohio's northern coast, Lake Erie laps into marinas, batters lighthouses, smoothes out sand beaches and erodes coastal backyards until the houses fall in.

For roughly 312 miles along Ohio's northern coast, Lake Erie laps into marinas, batters lighthouses, smoothes out sand beaches and erodes coastal backyards until the houses fall in.

Every so often, its waves sneak quietly into the mainland, mixing with a river flowing north.

In scientific terms, these areas are called estuaries - transition zones between riparian and littoral ecosystems that support a variety of plant and animal life. In tourism terms, they are inlets of intrigue - the raw clash of two natural worlds.

Most of Ohio's estuaries have been lost. They've been overtaken by marinas, filled in for housing developments, severed by roads.

Yet Old Woman Creek survives, stretching out from both sides of State Route 6 in Erie County.

To the north sits a thin barrier beach that in low water levels separates Erie from a small pool. To the south, a marsh flows wide and calm to a ring of forest. Both waterways are bejeweled with flowering lilies and the white flash of the great egret.

The real beauty, however, is what escapes the human eye.

Fish spawn at Old Woman Creek, and their young stay there to avoid deep-water predators. Local and migratory birds eat and nest throughout. The wetland acts like a kidney, removing impurities from a water source used by roughly 9 million people.

Because of its importance, Old Woman Creek is one of 27 research stations in the National Estuarine Research Reserve System. Scientists studying there have completed more than 200 research and monitoring projects.

"I always liken it to real estate - the three most important things are location, location, location," said Frank Lopez, a preserve manager with Ohio's Division of Wildlife. "Because they're situated on coastal areas, they provide benefits to that entire system."

Hard science aside, the preserve offers trails, boardwalks, observation decks and winding wooden staircases that tame the forest, prairies and marshes. Paddlers can hit the water with a day-use permit or sign up for numerous canoe exploration trips running through the fall.

If possible, head up before the middle of the month, when the water lilies will still be in full, glorious bloom.