The owners of 19 California coastal powerplants—including two nuclear facilities—may have to spend billions to install closed-loop cooling towers to protect marine life. The state Water Quality Control Board passed regulations on May 4 that require plants using once-through ocean-water intakes for cooling to reduce water use by more than 90%. + Image Image: Southern California Edison Intake protection system at San Onofre is part of a previous $150-million mitigation. The rule, finalized by the board after five years of study and hours of debate, cites estimated annual mortality rates of 2.6 million fish and 19 billion fish larvae from
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.