Carabell/Rapanos Decision

I haven't read the decision announced yesterday yet, but these are of course critical questions in environmental law: for the purposes of the Clean Water Act, when is a water a "navigable water"?

Justice Kennedy writes:

[W]etlands possess the requisite nexus, and thus come within the statutory phrase 'navigable waters,' if the wetlands either alone or in combination with similarly situated lands in the region, significantly affect the chemical, physical, and biological integrity of other covered waters more readily understood as 'navigable.' When, in contrast, wetlands’ effects on water quality are speculative or insubstantial, they fall outside the zone fairly encompassed by the statutory term 'navigable waters.'

[NB: I pulled this quote from SCOTUSBlog The blog's first note on the decision is here, and others follow the one from which I quoted.]

This is a very interesting, result-oriented approach to the definition. Rather than tackling a more positive definition of width or length or seasonality (i.e., does it dry up for part of the year), the Justice seems to be trying to avoid all that and instead ask, "what is the effect of this water?"

Thoughts? Predictions? Effects peculiar to Massachusetts or New England?