During 2003 a U.S. Supreme Court (SCOTUS) ruling on Sackett v Environmental Protection Agency determined that ephemeral streams are not protected under the Clean Water Act leading to a revision of the WOTUS Rule.  By definition, ephemeral streams contain water only following rainfall and may be dry for extended periods.  Following this decision, a June 2024 reversal of the Chevron Defense in Loper Bright Enterprises v Raimondo has deprived scientists, economists and specialists within federal agencies of the right to interpret ambiguous legislation following a “reasonable and rational” consideration of issues.  Chief Justice John Roberts in the majority opinion noted “The implicit delegation of authority to Agencies was ‘misguided’ because Agencies have no special competence in resolving statutory ambiguities”. Accordingly, jurors will now become hydrologists in addition to their acquired expertise as gynecologists, pharmacologists and epidemiologists.

The Sackett decision is now clearly unfounded based on recent research conducted at the University of Massachusetts, Amherst.  Dr. Craig Brinkerhoff and colleagues mentored by Dr. Colin Gleason, Professor of Civil And Environmental Engineering clearly demonstrated the contribution of ephemeral streams to water flow in rivers.  These bodies of water may contribute as much as 55 percent of water that reaches the mouth of river systems across the U.S east of the Rockies.  In some areas, ephemeral streams in mountainous areas of Nevada and California may contribute 90 percent or more of water reaching the termination of western river systems.

Research leading to the recognition of the importance of ephemeral streams included application of hydrologic models based on field data.  This approach was used to determine the proportion of the river flow derived from ephemeral streams.

Dr. Brinkerhoff concluded that the study provided evidence that the contribution of ephemeral streams is significant to major waterways.  Accordingly, pollution in ephemeral streams that are now excluded from EPA jurisdiction will become greater sources of pollution unless appropriate state and local control is applied.  The implications of the research conducted at the University of Massachusetts is exemplified by Dr. Brinkerhoff in “all things are connected; we cannot regulate water bodies ad hoc”.