Places We Protect

Johnsonburg Swamp Preserve

New Jersey

Located in Warren and Sussex Counties, New Jersey.
Johnsonburg Swamp Preserve Located in Warren and Sussex Counties, New Jersey. © Dwight Hiscano

Johnsonburg Swamp Nature Preserve is one of the most species-rich natural areas in New Jersey.



Why is This Land Special?

Established in 1990, Johnsonburg Swamp Preserve protects a limestone forest and is considered one of the most important and species-rich natural areas in the state. Mud Pond, at the heart of the preserve, is a limestone wetland providing excellent habitat for rare plant species, along with waterfowl and other wildlife. The scenic limestone outcrops that overlook the pond to the west and north are the largest rock formations of their kind in the state.

It is this limestone bedrock that produces the calcium-rich soil in which Johnsonburg's rare plants flourish. Examples include hoary willow (Salix candida), ebony sedge (Carex eburnea), leathery grape-fern (Botrychium multifidum), white-grained mountain rice grass (Oryzopsis asperifolia) and lesser bladderwort (Utricularia minor), which is found at only three other sites in New Jersey. This carnivorous plant produces yellow flowers and floats in the water, where it periodically extends the equivalent of a small trap door that sucks in insects that brush against it.

Threatened wildlife that make their homes around Mud Pond include great blue herons (Ardea herodias), red-headed woodpeckers (Melanerpes erythocephalus), barred owls (Strix varia), red-shouldered hawks (Buteo lineatus), wood turtles (Clemmys insculpta) and longtail salamanders (Eurycea longicauda longicauda). Red-spotted newts (Notophthalmus viridescens), though not threatened, are commonly found in the moist forested areas of the preserve.

Samuel Green, a prominent surveyor, was the first European settler in the area in 1730. For the next two centuries, agriculture dominated the landscape. In recent decades, dairy farms dotted the rolling hills of the area, and the Erie-Lackawanna Railroad roared through Johnsonburg. In the 1970s the railroad closed. Today, the area is beginning to see an increase in housing development.




Dawn until dusk


Hiking, birding, wildlife viewing


714 acres

Explore our work in this region

Visitation Guidelines

  • Please stay on the trail.
  • No fishing, hunting, trapping or collecting.
  • Motorized vehicles and aircraft are prohibited.
  • Bicycling, camping, fires (other than authorized prescribed fires), firearms, rock climbing, spelunking, swimming and feeding animals are prohibited.
  • Horseback riding is by permit only.
  • Pets (except for seeing-eye dogs) are prohibited.

A trail exists for hiking and sight-seeing. The preserve is open from dawn until dusk.

Support Our Work at Johnsonburg Swamp Preserve

You can help us protect New Jersey's diverse plant and animal communities.

A great blue heron (Ardea herodias) wades with purpose in shallow wetland waters in search of fish, Massachusetts.
Great Blue Heron Many threatened species make their homes around Mud Pond in Johnsonburg Swamp Preserve. © Cheryl Rose