How Does Urbanization Affect the Watershed?
The 1998 listing of Lower Columbia steelhead salmon as threatened and Upper Columbia steelhead as endangered brought watershed problems home to the cities in the Columbia Basin. Steelhead, like other anadromous species, need cold, clean water, and sufficient water for migration, spawning, and rearing. They spend one to three years in freshwater before heading to the ocean; they are, therefore, especially vulnerable to the dangers of dewatered, polluted streams. Paved surfaces above, cleared slopes below, and heavy rain created a landslide. 22 Effects of Urbanization Concentrations of housing, business, industry, and roads-in short, towns and cities, and even rural residential areas-radically alter the capture, storage, and release of water. Local streams are usually confined by channels, pipes, or culverts, or even filled in. Extensive paved surfaces prevent rain from filtering into the soil and send it off into drains and ditches carrying sediments and chemicals from countless human a
