Imagine canoeing through a narrow channel surrounded by cattails, bulrush and marsh grasses. In the distance, you hear the loud, distinctive wow-wow-ou of tundra swans.

Paddling around a bend, you come upon a great blue heron standing in 18 inches of water. Startled, the majestic bird jumps with its long legs and, spreading its six-foot wingspan, gracefully rises above the sea of marsh grass.

The narrow channel begins to widen into a large expanse of open water. In front of you are hundreds of ducks, mostly mallards, but also wigeons, pintails, green-winged teal and even a few ringnecks.

Looking up, against the horizon, you see some of the tall buildings that make up the Detroit skyline.

This is the St. Clair River Delta, locally called The Flats.

The St. Clair Flats is the largest freshwater delta in the United States. It is located only 25 miles from northeast Detroit and is less than an hour's drive for the four million people who live in southeast Michigan.

"The Flats is one of the most amazing places in Michigan," said Department of Natural Resources Wildlife Biologist Ernie Kafcas. "Many people are surprised it is so close to a major metro-politan area. It is very rewarding to be one of the people responsible for managing such an ecologically important place."

Unique to the Great Lakes, the Flats were created thousands of years ago at the mouth of the St. Clair River by the accumulation of sediment into the shallower Lake St. Clair basin. The combination of a relatively flat landscape sloping toward Lake St. Clair, a thin layer of sand over clay, and the fluctuating water levels of Lake St. Clair produced the right conditions for coastal wetland complexes to develop in this region.

In size, the U.S. portion of the total Flats area is approximately 25,000 acres or 40 square miles. About 54% of that total is water; most of the remaining land area is made up by Harsens and Dickinson islands.

Despite the tremendous pressure imposed on the lake and delta by human inhabitation the Flats is a highly productive coastal marsh system that supports diverse and productive populations of fish and wildlife.

Lake St. Clair is nationally recognized as an important waterfowl migration flyway. Tens of thousands of waterfowl annually migrate through this region, and the Flats have a long and storied history of waterfowl hunting.

Although more than 75% of the basin's original wetlands have been lost since 1900, the remaining wetlands provide habitat for waterfowl resting, feeding and breeding. Two species of swans, three species of geese and 21 species of ducks have been recorded.

The Flats also are home to 39 species of amphibians and reptiles and 15 species of mammals, including deer, raccoons, red fox, muskrats and mink.

Birds other than waterfowl include two species of grebes, five species of rails, seven species of herons, three species of plovers, 12 species of sandpipers, seven species of gulls, four species of terns and eight species of hawks. This birder's paradise also includes the bald eagle, osprey, American kestrel, short-eared owl, belted kingfisher and dozens of common songbirds.

Lake St. Clair and the Flats also are heavily used for recreational boating and fishing. The lake supports more than 70 species of fish, with 48 species dependent on the wetlands and shallow areas of the lake. Popular sport fish are muskellunge, walleye, yellow perch, northern pike and smallmouth bass.

Two major natural communities, the Great Lakes marsh and lake plain prairie, which form the coastal wetland complexes, are very rare.

"Both of these communities are considered to be globally imperiled," Kafcas said. "It would be a tragedy to lose such an ecologically important area."

Valuable to both people and wildlife, Kafcas said that's why the DNR and others have been working to protect and restore wildlife habitat in this area for several decades.

The state owns and the DNR manages several thousand acres of wetland and agricultural land in the area, including the St. Clair Flats Wildlife Area, which consists of the St. Johns Marsh Wildlife Area, Harsens Island Wildlife Area and Algonac State Park.

It is through the hard work of the DNR and numerous partners that some of the detrimental impacts to the marsh are being reduced and restoration efforts are occurring.

Along the way, the DNR has been helped by numerous organizations, including Ducks Unlimited, the Harsens Island Waterfowl Hunters Association, the Michigan United Conservation Clubs District 8, the Michigan Duck Hunters Association Blue Water Chapter, St. Clair Flats Waterfowlers and Waterfowl USA.

In addition to efforts to protect and preserve the marsh, at Algonac State Park, several hundred acres of lake plain prairie, a very rare community in Michigan, have been successfully restored or enhanced through brush and tree control and prescribed burns.

The DNR also has worked cooperatively on a research study that is examining the effectiveness of the more than 20-mile system of dikes within the marsh.

"We're looking at the benefits and challenges associated with these important dikes, which control water levels and plant communities throughout the marsh," Kafcas said. "The information we're learning will help us become even better land managers."

Another recent DNR effort is to eradicate invasive nonnative species such as giant reedgrass, also known as phragmites.

"Phragmites has become a major problem and, as a wetland manager, I believe it is one of the greatest threats facing the marsh," said Kafcas. "A number of research projects are underway to find the most effective way to eradicate it. It is critical to stop the spread of this and other invasives before we lose such an incredible piece of Michigan's ecosystem."

If you've been to the Flats, you know just what Ernie Kafcas is talking about. If you haven't experienced the largest freshwater marsh in the United States, you should go. The place is truly amazing.