In 2015, the Environmental Protection Agency issued a new Clean Water Rule, a.k.a. Waters of the U.S. (WOTUS) rules defining the jurisdiction of the agency over rivers, lakes, creeks, estuaries, ponds, swamps, prairie potholes, irrigation ditches, and intermittent rivulets. The new rules were based on the EPA's interpretation of the provisions of the 1972 Clean Water Act that mandated that the agency devise "comprehensive progams for water pollution control" aimed at "preventing, reducing, or eliminating the pollution of the navigable waters and ground waters and improving the sanitary condition of surface and underground waters." The agency reasoned that it had authority to regulate non-navigable upstream water sources like farm ponds and intermittent streams since they could carry pollution down to navigable waters like lakes and rivers. These new rules brought nearly half of Alaska and a total area in the lower 48 states equivalent to the size of California under the Clean Water Act's jurisdiction.

The upshot is that under the new more extensive regulations, ranchers, farmers, and property developers had to seek permission from the U.S. Army of Corps of Engineers to make changes that might affect minor sources of water on their land. Obtaining permits could take years and cost thousands of dollars. At least 32 states have sued to prevent the new regulations from taking effect, and the Sixth Federal Appeals Circuit Court stayed the new rules in October, 2016.

At the Conservative Political Action Conference meeting last week, new EPA Administrator Scott Pruitt declared that the Obama administration's WOTUS regulation had "made puddles and dry creek beds across this country subject to the jurisdiction of Washington DC. That's going to change." The new executive order that President Trump is expected to sign today directs that EPA to reopen the rulemaking process to repeal and revise the WOTUS rules. The agency is explicitly told to use the standards set out in former Supreme Court Justice Antonin Scalia's plurality opinion in the 2006 Rapanos vs. United States case. In his opinion, Scalia declared:

In sum, on its only plausible interpretation, the phrase "the waters of the United States" includes only those relatively permanent, standing or continuously flowing bodies of water "forming geographic features" that are described in ordinary parlance as "streams[,] … oceans, rivers, [and] lakes." See Webster's Second 2882. The phrase does not include channels through which water flows intermittently or ephemerally, or channels that periodically provide drainage for rainfall. The Corps' expansive interpretation of the "the waters of the United States" is thus not "based on a permissible construction of the statute."

Of course, various activist groups are alarmed at the potential rollback of EPA authority. For example, Trout Unlimited issued a statement:

Gravity works cheap, and it never takes a day off. The Administration cannot stop water flowing downhill—and we all live downstream. To be effective, the Clean Water Act must be able to control pollution at its source, upstream in the headwaters and wetlands that flow downstream through communities to our major lakes, rivers, and bays. … If Justice Scalia's direction is followed, 60 percent of U.S. streams and 20 million acres of wetlands would lose protection of the Clean Water Act; an unmitigated disaster for fish and wildlife, hunting and fishing, and clean water.

In favor of Trump's new executive order American Farm Bureau Federation President Zippy Duvall declared:

President Trump's executive order to ditch the Waters of the U.S. rule is a welcome relief to farmers and ranchers across the country today. The flawed WOTUS rule has proven to be nothing more than a federal land grab, aimed at telling farmers and ranchers how to run their businesses. The Environmental Protection Agency failed to listen to farmers' and ranchers' concerns when drafting the rule and instead created widespread confusion for agriculture. Under the rule, the smallest pond or ditch could be declared a federal waterway.

In any case, the EPA review process will take years to complete.