Human Impacts on Stream Hydrology and Water Quality

More than 99% of streams and rivers are considered to be impacted by human activity. Such activity includes the conversion of land for intensive agriculture, the fast expansion of urban areas, and the growing use of fertilizers, pesticides, and other contaminants. With these changes, we have seen a pervasive homogenization of landscapes, leading to a decrease in the natural variability of stream behavior and putting both river ecosystem ecology and human settlements at risk. In addition, years of human activity have led to the development of physical and biogeochemical legacies that may have long-lasting impacts on water quality and stream behavior. Despite a growing commitment to stream restoration, some speculate that both the intensity of human impacts and the development of long-term legacies within watersheds have produced regime shifts that may make a return to a previous nonimpaired state nearly impossible.