A bridge to a lakeside campground spans part of Northern California’s Shasta Lake in November 2019. Created when the federal government finished the Shasta Dam in 1945, the reservoir is the third largest body of water in the state behind Lake Tahoe and the Salton Sea. (Courthouse News Photo / Chris Marshall) PARIS (AFP) — By 2050, more than half the global population will live downstream from tens of thousands of large dams near or past their intended lifespan, according to a U.N. report released Friday. Most of the world’s nearly 59,000 big dams — constructed between 1930 and 1970 — were designed to last 50 to 100 years, according to research from the U.N. University’s Institute for Water, Environment and Health.