Dam removal has been proposed as a way to reduce the risks to life and property from the possibility of dam failures and to restore damaged river ecosystems. With about 79,000 relatively large dams in the United States that pose “high” or “significant” risks in the event of failure, dam removal would be a huge and controversial undertaking. One example of the possibilities and difficulties of decommissioning dams is the September 2009 agreement to remove four dams on the Klamath River, beginning in 2020. The tentative agreement was reached by 28 different groups and took ten years to achieve. The agreement calls for three years of study and then a final decision by the U.S. Department of the Interior, assuming all of the parties sign off on the final agreement.