In its effort to clarify which waterways should receive federal protection under the Clean Water Act, the EPA under the current administration wants to exclude streams that flow only after rainfall, and wetlands without surface water connections to larger waterways.

But with the wide swings in weather patterns the U.S. has been experiencing in the past few decades, this could prove to be a moving target.

As reported by Environment and Energy Publishing, droughts that dry up wetlands, shrinking groundwater tables and increased rains could play havoc in determining which waterways reach the thresholds for federal protection and which do not.

The Army Corps of Engineers is in charge of specifying a waterway's status, which is then good for five years. But as EPA officials told a Science Advisory Board working group, "At the end of the permit period, a new jurisdictional determination might produce a different result if climatological changes had occurred, thus waters could come in and out of jurisdiction."

The current regulations, instituted by the Reagan administration and then later refined by the Obama administration, lower the chances of such five-year fluctuations because they "protect any streams with a streambed, banks or ordinary high-water mark," and "wetlands without surface water connections to waterways if they are relatively nearby or have shallow subsurface water connections."

The Science Advisory Board's working group offered the EPA four recommendations regarding the matter: to consider the scientific basis for excluding waters that only flow after rainfall, to do the same for wetlands without a direct connection to larger waters, to consider the scientific importance of groundwater, and to consider whether some waterways, even if they have year-round flow, are too small to deserve federal protection.