The Niobrara National Scenic River preserves 76 scenic miles and 28 recreational miles of the Niobrara River across north-central Nebraska, running east from Borman Bridge near Valentine to State Highway 137. It was designated in 1991 after a long study period and is widely listed among the top canoeing rivers in the country. The Niobrara is a national scenic river of an unusual kind - most of the corridor remains in private ownership, and management is coordinated among the National Park Service, the U.S. Fish and Wildlife Service (which runs the 19,000-acre Fort Niobrara National Wildlife Refuge), the Nebraska Game and Parks Commission (Smith Falls State Park, Borman Bridge WMA), private landowners, and the Niobrara Council, a local stakeholder organization. What makes the Niobrara distinctive is both hydrological and biogeographic. The river is fed primarily by seepage from the Ogallala Aquifer - estimated at roughly 70 percent of total flow - rather than by surface runoff. That steady groundwater supply gives the Niobrara an unusually consistent flow for a Great Plains river, with predictable levels that barely fluctuate seasonally. The same groundwater pushes out of the gorge walls as springs and small tributaries, feeding more than 200 waterfalls along the corridor. Smith Falls, at 63 feet, is the tallest waterfall in Nebraska. The valley itself has been called the biological crossroads of the Great Plains. Six distinct ecological communities converge here - northern boreal forest, Rocky Mountain forest, eastern deciduous forest, and three prairie communities (Sandhills, mixed-grass, and tallgrass) - in a band rarely more than a mile wide. Paper birch and aspen grow on north-facing slopes; ponderosa pine holds the dry south-facing slopes; bur oak and hackberry fill the bottomlands. The geology is visible in a way that little else in the Plains is. The Ash Hollow Formation and the underlying Valentine Formation, exposed in the gorge walls, record the region's 13-million-year sedimentary history - otherwise buried beneath deep soil everywhere else on the Great Plains. Fossil resources in the valley are regionally significant, and the adjacent Agate Fossil Beds National Monument protects some of the most important Miocene mammal fossil beds in North America. Paddling is mostly Class I with short Class I-II sections; several downstream rapids require portaging. Tubing is equally popular, with local outfitters in Valentine handling rentals and shuttles for day and multi-day trips. Wildlife on and adjacent to the corridor includes bison and elk on Fort Niobrara NWR, white-tailed deer, pronghorn, and mule deer. The river is administered jointly with Missouri National Recreational River, with a visitor contact station in Valentine, NE.