Today the main stem of the Columbia River has 14 dams, of which three are in Canada and 11 in the U.S. Four mainstem dams and four lower Snake River dams contain navigation locks to allow ship and barge passage from the ocean as far as Lewiston, Idaho.
The Romans built many dams and reservoirs for water collection, such as the Subiaco Dams, two of which fed the Anio Novus, one of the largest aqueducts of Rome.
The risk of failure was low for one dam, moderate for one, high for four and very high for four dams, two of which had already failed.
China is the world's biggest financer and builder of hydroelectric dams, many of which are being constructed in biologically diverse regions where the dams and their associated roads and power lines will open up new lands for exploitation.
Remove aging hydroelectric dams, many of which produce relatively small amounts of electricity and are soon up for relicensing.
Remove ageing hydroelectric dams, many of which produce relatively small amounts of electricity and are soon up for relicensing.
Tucked into the measure, however, was another spending plan: a $130 million initiative to rebuild an assortment of New Jersey dams, many of which are in Mr. Littell's district.
The 2008 Mw 7.9 Wenchuan earthquake triggered at least 257 landslide dams, most of which formed in series along rivers.
Currently there's a big push to remove dams, many of which have outlived their designed lifetimes and disrupt natural ecosystems.
Over the past several weeks, Lieutenant Rauch has spent tens of thousands of dollars to repair the dams, some of which are a half-century old.
The agency is considering removal requests for at least six other dams, many of which have bottled up once-productive salmon rivers in the Pacific north-west.
