Arizona’s two Republican senators believe EPA’s proposed definition of waters of the United States cannot be reasonably applied to the unique water systems in their state. 

In a letter to EPA Administrator Gina McCarthy, Senators John McCain and Jeff Flake take the standard position of those opposing the proposal—that EPA’s definition would “extend federal jurisdiction far beyond what could credibly be considered Congress’ intent” in the Clean Water Act.  The issue of tributaries as addressed in the proposal is of particular concern to the senators.

“For example, the proposed rule assumes that all tributaries of traditional navigable waters or interstate waters have a significant nexus to such waters and are therefore subject to regulation under the CWA [Clean Water Act], regardless of distance, size, function, or amount of regulatory flow,” write the senators. 

The significant nexus test was the basis of Supreme Court Justice Arthur Kennedy’s pivotal opinion in Rapanos v. EPA, which formed much of the basis for EPA’s proposal.  But the senators assert that it is difficult to see how EPA’s assumption that all tributaries have a significant nexus to a traditional navigable water, without any site-specific analysis, is consistent with Kennedy’s opinion. 

Ephemeral streams

In Arizona, the letter states, the vast majority of waters are desert washes that are part of ephemeral systems and often found at substantial distances from traditional navigable or interstate waters. 

“Under this proposal, every small ephemeral system of limited function, remote from traditional navigable or interstate waters, and with no practical ability to influence the physical, chemical, or biological integrity of those downstream waters would be regulated,” the senators write.  “In addition, unlike other states, Arizona is literally crisscrossed with man-made canals that are essential for critical water delivery.  Under EPA’s proposed assumptions, it is possible that every mile of these canals—including those that are not currently jurisdictional—will fall under EPA’s regulation.”

Since the definition will affect all the CWA’s regulatory programs, there will be a substantial impact on the state’s economy and particularly on the homebuilding and construction, agriculture, ranching, and mining sectors as well as on water delivery itself.

Lack of vegetation

The letter also raises the question of aridness in Arizona and other Southwestern states.  The EPA’s proposal would exempt gullies, rills, and swales from CWA jurisdiction.  In general, the Agency would identify such exempt water bodies by looking at vegetation to see if a flow has occurred.  However, vegetation that in other areas of the country is clear evidence of a swale or rill is often lacking in the Southwest.  In such cases, the EPA would look at the high-water mark and determine that regulation is required for water bodies that would be exempt in other parts of the country. 

According to McCain and Flake, this example is evidence that “troubling concerns unique to the arid Southwest in general and Arizona in particular have been given short shrift and merit additional analysis.”  The senators recommend that the EPA abandon its current proposed definition and develop a “meaningful proposal for evaluation that at a minimum limits federal jurisdiction and provides clarity and consistency for the regulated community.”

The McCain-Flake letter