The Cacapon (pronounced kuh-KAYpon) River flows north-northeasterly for 112 miles through Hardy, Hampshire, and Morgan counties of West Virginia. Its long, narrow watershed drains 680 square miles of the Eastern Panhandle. The Cacapon is a major tributary of the Potomac River.

The Lost and Cacapon are the same river. During dry spells, the Lost River is lost from sight when it flows under Sandy Ridge at "the Sinks." It emerges as the Cacapon a few miles downstream, just upriver of Wardensville. North River, a major tributary, joins the Cacapon at the Forks of Cacapon.

The Cacapon River and its corridor are biologically rich. Its banks are clothed by a diverse forest that includes silver maple, river birch, and sycamore in the canopy. Paw paw, black willow, and spicebush crowd the understory, and wildflowers, ferns, and grasses cover the ground. About 79 percent of the basin is forested, 19 percent is used as farmland, while the rest is towns and water.

In the spring, common riverside songsters include red-eyed vireo, song sparrow, indigo bunting, scarlet tanager, and eastern phoebe. The river also supports wood ducks, Canada geese, belted kingfishers, ospreys, and an occasional bald eagle. A globally rare plant, harperella, occurs in patches along the lower Cacapon, while rare animals include the wood turtle, red-bellied turtle, and several mussel species. Beaver and white-tailed deer are common.

In addition to Lost River's sink, other natural landmarks include the bicarbonate spring at Lost River State Park near Mathias; Caudy's Castle, a sandstone promontory on which, according to legend, a homesteader held off a group of Indians, near Bloomery; and Eades Fort, a large cliff along the lower Cacapon near Largent, where folklore holds that Indians captured a family of cave-dwelling settlers.

Lord Thomas Fairfax conveyed many of the original land plots to the watershed's homesteaders from 1748 to 1761, and George Washington surveyed many of these from 1749 to 1751. The first fort in the chain of defenses on the frontier was constructed by Washington's troops during the winter of 1756 at Great Cacapon, located at the Cacapon's mouth.

The Cacapon River has been the subject of several studies. Its remote, narrow valleys led the National Park Service to score the lower 80 miles of the Lost and Cacapon rivers as eligible for the federal Wild and Scenic Rivers System, but lack of local support prevented the section from being added to the system. Former U.S. Labor Secretary Willard Wirtz chronicled the basin's colorful people, such as Caudy Davis, and its quirky history, in his 1990 Capon Valley Sampler. The Cacapon is the first river in the nation for which a comprehensive ecological headwaters-to-mouth baseline has been assembled.

The Cacapon is a popular recreational stream. The main stem of the river supports a warm-water fishery of smallmouth bass and rock bass. Some tributaries support reproducing brook trout populations, while other reaches are stocked seasonally with rainbow trout. On average, May offers the best paddling because the weather is warm and the water level is adequate. Taking most of a day, the most popular float is the eight-mile stretch from Capon Bridge to Bloomery. Six summer camps, including the nationally renowned Camp Rim Rock for girls, challenge children with the river's boating and swimming.

The Cacapon River watershed lies in a narrow band of land west of the eastern megalopolis and east of the coalfields, a serendipitous siting that has contributed to the river's generally good health. Principal land uses include farming for poultry, cattle, and field crops, timber harvesting and second homes of absentee landowners.