A proposed high-voltage power line between northern Iowa and southwestern Wisconsin faces yet another legal challenge. Environmental groups sued the Army Corps of Engineers in federal court Wednesday over its permit allowing utilities to place towers in the Mississippi River for the $492 million project known as Cardinal-Hickory Creek. The National Wildlife Refuge Association, Driftless Area Land Conservancy and three other organizations say the agency violated federal environmental law by failing to take a âhard lookâ at the environmental consequences of the 102-mile line on public waters and lands, wildlife, recreation and property values. The EPA is proposing to phase out the production and use of hydrofluorocarbons. Those gases are commonly used in refrigerators and air conditioners and are considered a major driver of global warming. The proposed rule follows through on a law Congress passed back in December. It would decrease U.S. production and use of the gases by 85% over the next 15 years. The phaseout reportedly has support both from environmental groups and within the manufacturing industry.Additional reporting by The Associated Press.