In the past century the Grande Ronde basin in northeastern Oregon has been subject to numerous changes in land use and resource development practices including mining, logging, road construction, grazing, and irrigated agriculture. The impacts from these practices are spread throughout the basin and surrounding areas and have caused considerable changes to terrestrial and aquatic habitats. Many observed habitat impacts, including increased water temperature, loss of riparian vegetation, erosion, increased stream channelization, and increased sedimentation have more than one potential source, thus, it is often difficult to pinpoint the exact cause of a change in conditions. Vannote et al.’s (1980) river continuum concept (RCC) hypothesizes that physical variables within a river system will follow a gradient from headwaters to mouth, and this gradient should prompt a series of biotic adjustments that will conform to the continuum. This paper asserts that due to the extensive land use activity present in the Grande Ronde basin, land use impacts are prevalent enough to cause discontinuities in the predicted physical continuum of the Grande Ronde River.
Historical land & resource use in the Grande Ronde basin, Oregon