 US EPA regulations favors recirculating systems, even forcing some older power plants to replace existing once-through cooling systems with new recirculating systems.A 2008 study by the Associated Press found that of the 104 nuclear reactors in the U.S., "... 24 are in areas experiencing the most severe levels of drought.All but two are built on the shores of lakes and rivers and rely on submerged intake pipes to draw billions of gallons of water for use in cooling and condensing steam after it has turned the plants’ turbines," much like all Rankine cycle power plants.