What’s all the fuss about WOTUS?

In a nutshell, WOTUS or Waters of the United States, is a rule proposed by the U.S. Environmental Protection Agency and the Army Corps of Engineers to define which waters are subject to the Clean Water Act.  In 2015, these agencies established a rule that defined WOTUS as “…those waters that require protection in order to restore and maintain the chemical, physical, or biological integrity of traditional navigable waters, interstate waters, and the territorial seas” (Fed. Reg. 80 FR 37053).


In the continental United States, more than 357,000 miles of streams provide water for public drinking water systems. Of that total, over half only flow after rain or in certain times of the year. Approximately 117 million people get some or all of their drinking water from public drinking water systems that rely in part on these streams.
Photo by Danny Hart, U.S. EPA (CC-0)

The important element of this rule was that it included waterways, such as headwaters and wetlands, which expand the prior scope of the Clean Water Act, and highlighted the importance of connectivity between waterways, as well as the critical roles that these waterways play in “…controlling sediment, filtering pollutants, reducing flooding, providing habitat for fish and other aquatic wildlife, and many other vital chemical, physical, and biological processes” (Fed. Reg. 80 FR 37053).


Aerial view of braided wetlands and tundra that is typical of the Bristol Bay watershed in Alaska.  Upper Talarik Creek (shown here) flows into Lake Iliamna and then the Kvichak River before emptying into Bristol Bay.   Photo by U.S. EPA (CC-0)

The current administration has proposed a rule that would rescind the 2015 rule discussed above.  A recent paper by Kevin Boyle and colleagues in Science established that the regulatory impact analyses performed by the EPA and Army Corps based on each of the 2015 and 2017 rules came to vastly different conclusions: the benefit-cost analysis based on the 2017 rule found that benefits decreased by close to 90% compared to the 2015 rule.  However, this large and significant decrease excludes the benefits provided by wetlands, which could be near a half billion dollars based on the 2015 rule.


A blue heron eats a small fish in a wetland.  Photo by U.S. EPA (CC-0)

Time and time again, studies find that wetlands provide many critical ecosystem services that hold significant monetary value [1].  Excluding wetlands greatly underestimates the significant value that these systems hold.  Given that wetlands already have been lost from the US at staggering rates (>400,000 acres per year in the 1950s-1970s [2]), it is critical to protect these highly threatened ecosystems.

[1] Millenium Ecosystem Assessment, Ecosystem Services and Human Well-being: Wetlands and Water Synthesis

[2] US Fish and Wildlife Service, National Wetlands Inventory, National Status and Trends Reports

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