Prior to the settlement of the United States by Europeans and others, Native Americans utilized riparian areas for a number of purposes. Lakes and waterways, bounded by riparian plant communities and landforms, provided important transportation corridors. Riparian areas were natural producers of berries, seeds, roots, herbs, and other plant parts useful to these early societies. A plethora of wildlife species commonly found within riparian areas complemented the fisheries resources of the adjacent streams and lakes. And because of their proximity to water, riparian systems became synonymous with availability of water for human consumption as well as with relief from the hot and dry conditions common to many portions of the western United States.
With the advent of European settlement, initially in the eastern United States and subsequently across the Midwest and West, rivers and riparian systems were heavily utilized and significantly altered, a trend that continues today. Major rivers continued to serve as transportation corridors, and streamside forests provided fuel for steam-powered riverboats. The use of waterways for transportation provided an impetus for both clearing large wood from channels and reducing the potential recruitment of large wood into stream channels by harvesting streamside trees (Maser and Sedell, 1994). Furthermore, floodplain soils were extremely fertile, and thus vast areas of riparian forests were cleared for farming. In the Midwest, the ditching and draining of extensive floodplains and other low-lying areas for agricultural production ensured loss of many riparian systems. Riparian trees, because of their size, quality of wood, and closeness to a river or stream where they could easily be floated to a downstream sawmill, were highly valued, which greatly increased their likelihood of being harvested.
Thousands of miles of the nation’s highways and railroads have been constructed along waterways (Rose, 1976; Jensen, 1993; Lewty, 1995), creating significant impacts to riparian systems including removal of riparian vegetation; “hardening” of streambanks with concrete, rip-rap, or other means; realignment of channels; and increased sediment production. In the western United States, the construction of dams and other water control structures for power generation and irrigation diversions followed by the subsequent alteration to downstream hydrologic regimes have additionally influenced the extent, quality, and functioning of many riparian systems (Reisner, 1987). In other instances, concern about the water use of streamside vegetation in the southwestern United States during the 1960s led to the initiation of programs directed at the removal of “phreatophytic” (water-loving) vegetation along watercourses (Culler, 1970). Historic livestock production has also impaired riparian function, with western riparian areas being repeatedly overgrazed during most of the nineteenth and twentieth centuries. In recent decades, the rates of urbanization and recreational development along waterways have accelerated and greatly altered many of the nation’s riparian areas. By any ledger—physical, biological, or social—the impacts and extent of