Pollution laws and regulations

FILE - In this Jan. 5, 2015, file photo, Dodge Ram pickup trucks are on display on the lot at Landmark Dodge Chrysler Jeep RAM in Morrow, Ga. In a lawsuit filed Tuesday, May 23, 2017, the U.S. government is suing Fiat Chrysler, alleging that some diesel pickup trucks and Jeeps cheat on emissions tests. The Justice Department lawsuit alleges that nearly 104,000 Ram pickups and Jeep Grand Cherokees from the 2014 to 2016 model years have software that allows them to emit lower amounts of pollutants during lab tests by the Environmental Protection Agency than during normal driving conditions. (AP Photo/John Bazemore, File)

FILE - In this July 13, 2007 file photo, a worker with the Pebble Mine project digs in the Bristol Bay region of Alaska near the village of Iliamma, Alaska. The Trump administration settled a lawsuit Friday, May 12, 2017, over the proposed development of a massive copper and gold deposit near the headwaters of a world-premier salmon fishery in southwest Alaska. (AP Photo/Al Grillo,File)

FILE - In this July 13, 2007 file photo, workers with the Pebble Mine project test drill in the Bristol Bay region of Alaska near the village of Iliamma. The Trump administration settled a lawsuit Friday, May 12, 2017, over the proposed development of a massive gold and copper mine at the headwaters of one of Alaska's premier salmon fisheries. The Environmental Protection Agency settled the long-running case with the Pebble Limited Partnership, agreeing to allow the Canadian-owned company to seek a federal permit to build its mine near Bristol Bay. (AP Photo/Al Grillo, File)

Sen. John Barrasso, R-Wyo., chairman of the Senate Environment and Public Works Committee, leaves the chamber following a surprising win for environmentalists and Democrats and a blow to the fossil-fuel industry, as the Republican-led Senate failed in a bid to reverse an Obama-era regulation restricting harmful methane emissions that escape from oil and gas wells on federal land, at the Capitol in Washington, Wednesday, May 10, 2017. (AP Photo/J. Scott Applewhite)

FILE - Int his April 1, 2017, file photo, Sen. Rob Portman, R-Ohio, speaks before Vice President Mike Pence in Reynoldsburg, Ohio. Republicans from energy-producing states are under pressure as the Senate considers whether to overturn an Obama-era regulation that would restrict harmful methane emissions escaping from oil and gas wells on public land. Portman said May 8, he will support the repeal effort after weeks of public silence, saying he got assurances from Interior Secretary Ryan Zinke that he will take steps to reduce methane waste. (AP Photo/John Minchillo, File)