The entrance to Smallwood State Park was rerouted years ago, with one goal in mind-to answer the call of the river.

It's a "bring your own boat" situation at this popular park in southern Maryland, and most visitors are happy to oblige. The new entrance provides a direct route to the boat launch and marina on Mattawoman Creek, where anglers are eager to cast their lines into one of the Chesapeake's most productive waterways.

Many also cruise around the bend, where Mattawoman Creek meets the Potomac River.

The combination provides access to one of the East Coast's premier fisheries and makes Smallwood State Park a frequent host to fishing tournaments that always draw a crowd. Fishing guide and author Ken Penrod calls Mattawoman a fantastic creek with "massive food sources, deep water sanctuary and every conceivable bass-attracting habitat known to man."

Despite its location-a virtual backyard to Washington, D.C.-Mattawoman Creek has avoided much of the ecological stress plaguing so many of the Bay's tributaries, at least for now.

A study by the Maryland Department of Natural Resources found the aquatic food web in Mattawoman Creek to be unusually healthy, with a population of juvenile anadromous fish that was more than 40 times greater than that of the other study sites. The creek's remarkable biodiversity includes 54 species of fish and four species of freshwater mussels.

Tournaments at Smallwood State Park attract local anglers, as well as those that travel with their families from Pennsylvania, Delaware and beyond. The park also works with programs that provide wounded veterans with a fishing expedition. The staff has built a large aluminum ramp so that veterans in wheelchairs can board the boats before they launch.

Fishermen regularly pull champion-size fish from the water, including large- and smallmouth bass, rockfish, catfish, white and yellow perch, carp and hardhead.

A weigh station is built into the decking near the boat launch and fishing piers.

Kenny Hartman, who manages several state parks for the Department of Natural Resources, says the bass are enormous. They are not alone. One of last year's tournaments brought in a 50-pound catfish.

Hartman was also impressed by a 12-pound snakehead, but he wasn't happy to see it. Snakeheads are an aggressive, nonnative species with a growing presence in the Potomac. "We know snakeheads are here, but that one was the largest anyone at the park has ever seen," Hartman said.

The lure of the water and its resources has a long history at Smallwood State Park, a member of the Chesapeake Gateways Network.

During colonial times, the land was part of a large plantation owned by the Smallwood family. The Smallwoods relied on a deep channel in Mattawoman Creek for moving tobacco to markets on the Potomac River and Chesapeake Bay.

When William Smallwood, an early Maryland governor and general in the Revolutionary War, built his home here in 1760, the house was designed to face the water.

Smallwood enjoyed the wealth of a southern planter, and was the highest ranking officer from Maryland to serve in the Revolutionary War. He was also a state senator. But like many aristocratic men of the time, Smallwood was overextended. He died in debt, without spouse or heirs, and his bills were settled by parceling out the estate to new owners and tenant farmers.

The brick manor house, known as Smallwood's Retreat, was dilapidated by 1898. Citizen volunteers rescued it from demise during the 1930s, when it served as a storage building for a local farm. In 1958, after organizing themselves as the Smallwood Foundation, the volunteers donated the reconstructed house and surrounding land for use as a state park.

Smallwood's Retreat now stands as an excellent example of tidewater architecture, lined with boxwoods and embraced by the shade of tall hardwoods. A large kitchen, separate from the house, is paired with an herb and vegetable garden under the arm of a large oak.

While fishing reigns at Smallwood Park, Hartman says these quieter spots are among his favorites. "The new entrance takes people right to the marina and kind of isolates this area up here," Hartman said. "So it's quiet, out of the way."

Smallwood's Retreat is open for tours on Sundays through September, along with a 19th-century tobacco barn that houses an exhibit on the life and times of General Smallwood.

Smallwood's water view is now blocked by a forest that offers campsites and hiking trails. The General's Trail is the main loop through the park, covering about 2.5 miles of mostly wooded terrain and the historic area.

A long, gently arching footbridge connects the trail and campsites to the marina. The bridge spans a patch of wetlands that feed Mattawoman Creek. There's activity overhead and underfoot.

Below the bridge is a rare sight. Mattawoman Creek is one of only three places in Maryland with a wild population of native American lotus. Here you'll find a field of it, with pale yellow flowers and broad round leaves that are often suspended over the surface of the water. Turtles tuck themselves along the sturdy stems.

Geese pick a path through the marsh, and the sky is busy with the business of herons, egrets and eagles. The dark mass of an eagle nest is perched among the trees on the inland side of the wetlands.

Mattawoman Creek is also home to Maryland's largest breeding wood duck population and serves as an important wintering ground for black ducks.

Both people and wildlife clearly respond to this creek. It is hoped that they'll respond to its needs as well. The water quality and aquatic habitat in Mattawoman Creek are threatened by the proposal for a new four-lane highway and the increased urbanization it would draw.

Some say the "Cross County Connector" is needed to accommodate the surge in population that is predicted for Charles County. But the proposed project will cross through sensitive headwater areas and will impact federally regulated wetlands and state-regulated buffers and wetlands.

In April, American Rivers named Mattawoman Creek as one of the 10 most threatened rivers in the nation.

"The only place this highway will lead is to dirty water, more traffic, and poorly planned development," said Rebecca Wodder, president of American Rivers. "Mattawoman Creek is a treasure of the Chesapeake Bay and we must keep it that way."

Hartman said that water quality is the crux of the park's popularity, and the benefits it brings to the local economy. "Without it, the fish won't be there, and the boaters won't be out there either," Hartman said.

Smallwood State Park

The grounds and marina at Smallwood State Park are open year-round from dawn to dusk. Smallwood's Retreat and tobacco barn are open 1-5 p.m. Sundays, May through September, or by appointment. Family campsites and group camping are available from April 3 to Nov. 2 in 2009. Call for reservations, especially on tournament weekends.

Entrance fees are $3/person on weekends and holidays from April through October; $3/vehicle at all other times. The boat launch fee is $10/vehicle. Out-of-state residents add $1 to all standard fees.

Camping fees vary; call for details. Note: Fishing from shore or by boat requires a Chesapeake Bay Sportfishing License, available at the marina. Tours of Smallwood's Retreat are free.

Contact the park for information about the many fishing tournaments that take place at Smallwood State Park throughout the year.

Directions: Take Route 301 to La Plata, then Route 225 west. Turn left at light onto Route 224 south. From Washington, D.C., take Route 210 south toward Indian Head, turning onto Route 225 east. Turn right at light onto Route 224 south. Park entrance is about 3 miles on the right along Route 224.

For details about Smallwood State Park, go to www.dnr.state.md.us/publiclands/southern/smallwood.html. or call 301-743-7613 (1-888-432-CAMP [2267] for campsite reservations). For details about other sites in the Chesapeake Bay Gateways Network, visit www.baygateways.net.