Proposed "Waters of the U.S." Rule: What Is Left of the Significant Nexus Test?

Yesterday, we continued examining the confusion inherent in EPA and the Corps' proposed rule redefining "Waters of the U.S."  Today we finish that analysis by asking what is left of the Significant Nexus test, if anything.

As we discussed on Monday, the proposed rule tries to have its cake and eat it too.  The rule describes certain waters that are deemed always to have a significant nexus - and so are always jurisdictional - but also retains the significant nexus test for use on case-by-case basis.  As a reminder, under the proposed rule, "significant nexus" waters are jurisdictional if

alone or in combination with other similarly situated waters in the region. . . [they] significantly affect[] the chemical, physical, or biological integrity of a [traditionally navigable or interstate water or the territorial seas]

(Our emphasis). This test, which the agencies have been using since 2007 used to be opaque; its place in the new rule makes it even more so.

First, the rule retains the "aggregation" component - A water need not be significant on its own, but can be jurisdictional even if it is only significant in combination with other similarly situated waters in the region.  The rule does not define either of these terms, although it refers to both in the preamble.  The agencies refer to similarly situated waters as those that "perform similar functions and are located sufficiently close together or. . . are sufficiently close to a jurisdictional water."  This clarification provides little, if any, clarity.  The agencies implicitly acknowledge as much by stating that "[h]ow these "˜other waters' are aggregated for a case-specific significant nexus analysis depends on the functions they perform and their spatial arrangement within the "region" or watershed."

Slightly less opaque is the term region, which the preamble describes as "the watershed that drains to the nearest traditional navigable water, interstate water, or the territorial seas through a single point of entry."  However, the agencies are seeking comments on changing the interpretation to one which "would result in few if any other waters being found jurisdictional" or possibly one which "would lead to all similarly situated other waters within single point of entry watersheds within an ecoregion being found jurisdictional."  Or something in between.  So stay tuned.

But the more fundamental problem with the significant nexus test is its retention in the face of the new term tributary and the newly-robust term adjacent.  As discussed yesterday, tributaries are always jurisdictional under the proposed rule.  If flow is contributed to a downstream water by either (1) channel features with a bed and bank or (2) lakes, ponds or wetlands without a bed and bank water, the rule considers the feature to be a tributary and therefore jurisdictional.  Waters adjacent to tributaries - those in the same floodplain or riparian area are also automatically jurisdictional.

So the significant nexus test is therefore for other waters.

But what are these other waters?  By definition, they "significantly affect[] the chemical, physical, or biological integrity" of a downstream water but, by exclusion, (1) don't contribute flow to it (2) aren't in the water's floodplain and (3) aren't in the riparian area of the water.  Recall that a riparian area is one bordering any water where surface or groundwater "directly influence the ecological processes and plant and animal community structure in that area."

It is completely unclear how a water can significantly affect the

  • biological integrity of a water without directly influencing the ecological processes and plant and animal community structure in the area or
  • chemical or physical integrity of a water without contributing flow to it or being proximate enough to it that is in its floodplain

But the water must do so to pass the significant nexus test. 

The result is that, in retaining the significant nexus test in light of the expansive definition of tributary and the newly robust term adjacent, the agencies have created confusion as to what other waters may have a "significant nexus."  The term must exist for some waters, but it is unclear which ones they are.

*  * *

This is the last of our "high-level" posts analyzing the proposed rule; we'll now turn to some of the rule's practical implications and a few of the more detailed questions it raises.  Before we do, we note that one of our hopes for this rule - which has been over a decade in the making - was that it would increase regulatory clarity, efficiency and intuitiveness.  Determining jurisdiction - for wetlands in particular - has become so obtuse that there is little innate correlation between downstream traditionally navigable waters and upstream jurisdictional ones.  Scientists and regulators may be able to draw downstream connections and identify upstream features, but it is very difficult for laypersons to do so.  Like the tax code, the law of wetland jurisdiction has become so complex that it requires experts to interpret and parse.  We had hoped that this rulemaking might untangle the complexity.  As proposed, it does not and, to some degree, provides more string and further snarls the knot.

This is the seventh in a series of posts regarding EPA and the Corps' proposed rule redefining "waters of the United States" under the Clean Water Act.

Photo credit: Foter / CC BY-SA