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Illinois

Grassy Slough Preserve in the Cache River Wetlands

The wetlands here have been designated as one of only 15 "Wetlands of International Importance."


Why You Should Visit
Throughout the Cache River Wetlands, in what is now more than 45,000 acres of protected land, cypress and tupelo swamps can be found, seeming to belong more to Louisiana than Illinois. Cypress trees that are more than a thousand years old raise their gnarled branches above the black waters here.

The Grassy Slough Preserve, the Conservancy's signature project in the Cache River Wetlands, was once mostly forested wetland and efforts are underway to restore the site to its original condition. The lower stretch of the river spreads out over the flat terrain of extreme southern Illinois and creates what early surveyors to the region described as "a drowned land."

Because of their rich biological variety, the wetlands of the Cache River have been designated as one of only 15 "Wetlands of International Importance." This designation from the Ramsar Convention of the United Nations Educational, Scientific and Cultural Organization ranks the Cache River Wetlands with other important wetlands, such as the Florida Everglades.

Location
Between Karnak and Belknap in southern Illinois

Hours
Open from sunrise to sunset

Conditions
The Conservancy suggests wearing long pants, sturdy shoes and sun protection.

Why the Conservancy Selected This Site
The thick, lush vegetation of the hardwood forests and swamps in the Cache watershed were once home to many large mammal species that are no longer found in the region. Forest loss in the watershed due to logging and agriculture, especially along the lower stretch of the Cache, has been extensive.

Efforts to dry out the region have resulted in modifications to the Cache that have severely affected its natural flow. This has degraded the river and associated cypress and shrub swamps. Water quality of the river has suffered greatly, due in part to soil erosion from cleared land in the watershed. Up to 150 tons of soil per acre is washed into the river and wetlands each year.

What the Conservancy Has Done/Is Doing
The Nature Conservancy is working at the Grassy Slough Preserve as part of the Cache River Joint Venture Program (JVP), a unique public-private partnership between the Illinois Department of Natural Resources, Natural Resource Conservation Service (NRCS), U.S. Fish and Wildlife Service, Ducks Unlimited and the Conservancy.

Through this partnership, nearly 35,000 acres of the Cache River Wetlands are in conservation ownership, despite changes to the river, deforestation and decades of wetlands loss. Additionally, local landowners have protected 13,500 acres of restored wetlands through NRCS’ Wetland Reserve Program. Also through NRCS, landowners are using a variety of conservation practices, such as no-till conservation tillage, grassed waterways and reforestation; many of these practices are through NRCS' Environmental Quality Incentives and Wildlife Habitat Programs. In all, more than 45,000 acres of private lands are using some sort of NRCS conservation program in the Cache River Watershed.

The Conservancy received funding from NRCS’ Wetland Reserve Program to restore native habitats at Grassy Slough. The restoration, which includes the creation of wetlands and the planting of bottomland hardwood tree seedlings and canebrakes, will bring the total land restored on the former vegetable farm to approximately 1,600 acres of forest and 700 acres of wetlands.

While habitat restoration is very important, much of the success of restoration efforts in the Cache depend on restoring hydrologic connectivity between the Upper and Lower Cache River. Grassy Slough Preserve is an integral component in the attempt to restore these flows because it is located adjacent to the diversion between the Upper and Lower Cache River. The preserve also provides an important connection between protected lands up and down river.

The Cache, like other rivers, needs free-flowing water to be healthy. A current brings oxygen and dissolved nutrients, while moving sediments and pollutants out of the system. For the Cache and adjacent wetlands to remain healthy for future generations, some amount of flow must be re-established between its upper and lower segments. Otherwise, 40 years of investment in conservation could be in jeopardy.

How You Can Help
Please see “Ways of Giving.”

What to See: Plants
Bottomland hardwood forests are dominated by overcup oak, pin oak, cherrybark oak and sweetgum that give way to red oak, white oak and shagbark hickory trees. Barrens occur on the highest ridge tops where soils are thin and bedrock is exposed.
These sites are dominated by small post oak and blackjack oak trees, scattered about open expanses of land that are dominated by grasses and forbs more commonly encountered on dry prairies. Cypress and tupelo trees and thickets of buttonbush occur in areas of shallow water.

What to See: Animals
Restored wetlands attract a myriad of bird species, including migrating waterfowl and shorebirds, bald eagles, great blue herons and great egrets. Bird-voiced tree frogs, southern leopard frogs, spring peepers, western chorus frogs, bullfrogs and American toads are among the more vocal of the area's amphibian inhabitants. Mammals found at Grassy Slough include white-tailed deer, squirrels, raccoons, beavers, gray foxes, red foxes, opossums, skunks and mink.

Grassy Slough Preserve Map

Begin your adventure at the Cache River Wetlands Center, which is open Wednesday through Sunday from 9 am to 4 pm. The Wetlands Center is located at 8885 State Route 37, Cypress, IL, 62923.

From the Center, you can visit all the various preserves that comprise the Cache River Wetlands area, including the Conservancy’s Grassy Slough. These preserves offer:

  • Scenic Overlooks
  • Hiking Trails
  • Boardwalks
  • Canoeing
  • Biking along the historic Tunnel Hill Trail

One of the best ways to see the Cache River is by canoe or kayak. The Cache River Joint Venture Partnership and the Friends of the Cache River Watershed offer canoe trips along the Cache, as well as various educational workshops about the flora and fauna of the area. Check out the Friends’ web site for an updated list of activities.

Volunteer Opportunities
Please contact Karen Tharp at ktharp@tnc.org or 618-634-2524 for volunteer opportunities at the Cache River Wetlands.

Hunting is now open to the public at the Grassy Slough Preserve. Before you plan your trip, please see our rules and regulations.

For information on ADA accessibility and use of OPDMDs, click here.

Directions

To the Conservancy’s Grassy Slough Preserve:
Take I-57 South; Exit 30 to IL-146 East towards Vienna; From IL-146, take a RIGHT (South) onto IL-37. Continue straight onto IL-37 South (you will pass the Cache River Wetlands Center); Take a LEFT (East) on IL-169, then a LEFT (North) on E 1st St./Karnak-Belknap Rd. Grassy Slough Overlook will be on your right side.
 

Discussion

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