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particular concern because unstable roads are known to be major sources of fine particles in some streams in the Flathead catchment, as elsewhere (see Megehan et al. this volume). Accelerated erosion, locally associated with logging and road building, has increased the volume of fine particles within the channel of disturbed streams, clogging interstices and reducing interflow and aeration of the substratum. Speciosity and biomass of zoobenthos may be reduced by 80% in highly sedimented areas compared to adjacent cobble substratum (Spies 1986) and survival of bull charr eggs and juveniles decreases markedly when fines (particles < 6.35 mm) exceed 40% of the substratum volume (Weaver and Fraley 1991). Moreover, recent work has shown a clear correlation between sedimentation rates in on-channel lakes and road building activities in the McDonald and Whitefish subcatchments (Spencer 1991). Inflow of riverine sediments apparently fertilize the water column of Flathead Lake in the spring based on the observation that phytoplankton productivity is highest in years of high runoff and high sediment loading from the catchment (J. Stanford and B. Ellis unpublished); however, the sediment load has not been apportioned in terms of natural versus human disturbances. Interactions Between Natural and Human Disturbances Manaaement Considerations Many different management jurisdictions exist within the Flathead River Basin. Seventy-two percent of the basin is federally administered, involving the Flathead National Forest (U.S. Department of Agriculture), Glacier National Park (National Park Service), National Wildlife Refuges (U.S. Fish and Wildlife Service) and the Flathead Indian Reservation trust lands (U.S. Bureau of Indian Affairs). Large areas of State and Tribal (Confederated Salish and Kootenai Tribes of the Flathead Indian Reservation) lands exist, with the remainder of the basin primarily in privately held tracts. Hungry Horse Dam is a federal project operated by the U.S. Bureau of Reclamation. Kerr Dam is located within the Flathead Indian Reservation and operated by a private corporation, Montana Power Company, Inc., on the basis of a rental agreement with the Tribes as mandated by the Federal Energy Regulatory Commission. Many other Federal, State and local agencies have statutory authority to manage specific resources in the catchment. Since the headwaters of the North Fork are in British Columbia (Figure 3), many additional provincial and Canadian Federal agencies are involved. For example, the authority of the International Joint Commission (organized under the U.S.-Canada Boundary Waters Treaty of 1909) was invoked during 1986 - 1988 to quantify and reference the potential impacts of a large open-pit coal mine (International Joint Commission 1988) proposed by a Canadian subsidiary of an American corporation in Canada (Figure 3). This maze of management jurisdictions 15