DES MOINES - Back in the 1990s, geese at the Nahant Marsh were dying, victims of lead poisoning from ammunition left on the site of what had been a sportsmen's club.

But today, this urban wetland near the Mississippi River is thriving, a mecca for bird enthusiasts, nature lovers and photographers nestled inside Davenport's city limits.

An area that had once been a Superfund site now serves as an example of how wetlands can be restored to play their crucial roles as a habitat for diverse wildlife and as an important water filter.

Brian Ritter, a facilitator at the marsh, credits the U.S. Environmental Protection Agency and local private groups with the restoration.

More than 140 bird species have been documented at the marsh, Ritter said as he spied several great blue herons outside his office window.

Ritter likes marshes for the wildlife that inhabit them.

"They're almost like the tropical rainforests of the north in terms of their biological diversity," Ritter said.

He also stresses wetlands' importance as a natural water filter that is vitally important for water quality.

"Marshes do a tremendous job of filtering clean water. Without marshes, our water would be a lot dirtier than it is," Ritter said.

The marsh mitigates flooding along the Mississippi River, which was highlighted by the floods this year, Ritter said.

The floods in part killed some of the area's prairie, and they've been overrun with 28 invasive plant species.

"If we don't do something to combat them eventually they'll just kind of take over," Ritter said.

A clean-up event with volunteers helped removed debris and trash deposited in the marsh area because of flooding and a windstorm, but Ritter said there are areas around the preserve where debris remains.

The floods also caused an explosion in the leopard frog population there, which has helped draw more birds.

"It's amazing how quickly it's recovered," Ritter said.

He hopes the restoration of the Nahant Marsh will serve as an example for the restoration of other wetlands around the region.

"It's been such a tremendous success story, and it definitely could have gone the wrong direction had it not been handled properly," Ritter said.

Iowa Department of Natural Resources Director Rich Leopold said the complex clean-up at Nahant was an unusually difficult situation for restoring wetlands.

"If they can do it at Nahant Marsh with what they were facing, we should be able to do it almost anywhere," Leopold said.

Charlotte Eby can be reached at 515-243-0138 or chareby@aol.com.