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EPA Defines Waters of the United States

September 5, 2014

The US Environmental Protection Agency has released a draft definition of the term “waters of the United States” as covered by the Clean Water Act (CWA). The CWA regulates entities that discharge any pollutants, including phosphorus (P), into said waters.  However, which waters are or are not covered has been very vague since its passage 40 years ago.  It was often necessary to hire consultants to make case-by-case determinations for an individual pond, ditch, swale, or marsh.  Entities would be required to gain a NPDES (National Pollutant Discharge Elimination System) permit to discharge elevated levels of P  if the water body was determined to be jurisdictional, but were unregulated if the water body was determined not to be.  It would often be difficult to make an unbiased determination since the entity doing the discharging was the same sponsoring the study and would benefit from a non-jurisdictional finding.  The EPA seeks to clarify this confusion, save time and money in the determination process, and have uniform application by proposing the clearer definition.

The proposed new definition of “waters of the United States” generally narrows the scope of coverage.  It does not cover any new types of water and still does not cover groundwater.  It continues to cover large waters that are currently or historically useful for navigation or recreation.  The major areas of clarification came in defining coverage for tributaries, neighboring wetlands, and ephemeral washes.  These are now clearly jurisdictional if they contribute physical, chemical, or biological impact to a downstream regulated body.

This elucidation enables better P management to prevent nutrient loading and eutrophication for at least two scenarios.  First, several upland soil and water conservation practices continue to be excluded from jurisdiction. In addition, 56 other conservation practices established by the Natural Resource Conservation Service (NRCS) are now clearly excluded. The farmer can now implement nutrient runoff prevention and erosion prevention improvements without the need to gain expensive and time-consuming dredge/fill permits. Second, upstream wetlands that contribute to downstream water quality are now clearly included as jurisdictional.  Entities can no longer discharge unacceptable levels of P into a wetland, previously justified by the wetland not being jurisdictional itself and only indirectly affecting downstream waters.  The new clearer definition works to reduce P pollution in both scenarios.

In what ways do you think clarifying “waters of the US” will impact P management?  Read the proposed rule at  The EPA is accepting public comments until October 2014.

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