At an April 27 hearing, GOP lawmakers blasted the U.S. Environmental Protection Agency for limiting the scope of the Pebble Mine project in Bristol Bay, Alaska, before the project’s developer had formally submitted plans and applied for a permit.

As construction industry groups await a Supreme Court ruling in a narrowly focused Clean Water Act case, they also are seeking clues as to how the justices may view a much more important matter that has not yet come before them—an expected frontal challenge to a wide-ranging U.S. Environmental Protection Agency-Army Corps of Engineers regulation governing federal jurisdiction over the “waters of the United States.”