The largest dam removal project in U.S. history is underway along the border between California and Oregon. Federal regulators approved a plan last year to remove four dams on the Klamath River. Work has already begun on removing the smallest of the four dams, Copco 2. The other three will come down next year. The dams were built decades ago to generate electricity. But they also halted the natural flow of the river and disrupted the lifecycle of salmon. The fish are culturally and spiritually important to several Native American tribes in the area. In 2002, a combination of low water levels and warm temperatures caused a bacterial outbreak that killed more than 34,000 fish. That propelled Native American tribes to campaign for removal of the dams. After much negotiation, federal regulators finally approved a plan last year to remove the dams. PacifiCorp transferred the dams to a nonprofit that will oversee the project. The dams are scheduled to be completely removed by the end of 2024. The project will cost about $500 million and is being paid for by taxpayers and utility ratepayers.