The EPA’s new rule which was unveiled on January 23 to replace the Obama administration’s Waters of the United States rule is expected to face major challenges in court as the Trump rule contains very little scientific justification for the change. The rule redefines which bodies of water are covered by federal antipollution laws, and is far narrower than the Obama administration’s version. The new policy excludes isolated wetlands and ephemeral streams that only flow after heavy rainfall. The 2015 Waters of the United States rule came with volumes of scientific justification, and the Trump administration will have to demonstrate to a judge why the science that backed the Obama administration’s much broader definition of a water body is wrong. Legal challenges are expected to be filed as soon as the new rule is published in the federal register which is expected any day.