Across the country, communities are identifying marginal dams, and challenging the relicensing of dams whose environmental impacts are too costly. Questioning the value of dams requires a serious readjustment in the country's notion of progress, a process daunting to all, threatening to some. Yet dams have been removed in Maine and North Carolina, in Oregon, Vermont, Wisconsin and California, as communities rethink priorities and commit themselves to river restoration. The number of dams in the country is estimated at 60,000 to 80,000. Dams alter and block the natural flow of rivers, interfering with fish migration, often destroying native fish populations.
Dams hold back silt, debris and other nutrients that create healthy environments for river species.
The number of dams in the country is estimated at 60,000 to 80,000. Dams alter and block the natural flow of rivers, interfering with fish migration, often destroying native fish populations. Northwest form an influential piece of the region's economy. In many places reservoirs created by dams are recreational magnets, ingrained in the custom and character of their communities. Damming for flood control, drinking water and the diversion of wetlands stimulated the growth of urban centers.