The U.S Army Corps has unveiled a $1.7-billion, 10-year plan to restore to health the ailing Anacostia River in the Washington, D.C., metropolitan area. The plan, two years in the making and released on April 19, identifies 3,000 projects to help restore the severely polluted river and watershed spanning 176 sq miles of land through a combination of stormwater controls, stream restoration, wetland creation and restoration, fish blockage removal, reforestation, and controlling trash and chemical contamination. However, finding funding to pay for the projects could be a challenge. Funding for the plan was authorized under the Water Resources and Development
Arch dams, classically curved monoliths situated in narrow valleys, are not as common as other types of dams, such as embankment dams and gravity dams. ENR takes a look at some of the biggest arch dams in the world, both completed and under construction.