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Intermittent Streams Under the 2020 WOTUS Rule: A View From the Field

Updated: Sep 16

When the new WOTUS rule was proposed earlier this year, I commented that it would not be easy to administer, despite the pronouncements to the contrary from EPA.


I'm now doing work with a client who has a pond on an intermittent stream. Under the 2015 Rule, the analysis would be easy. It would be jurisdictional as a tributary. Period.


Under the new rule, I need to know whether the stream fits the definition of ephemeral or intermittent to know whether it's covered. To do that, I need to know if it has "surface water flowing continuously during certain times of the year and more than in direct response to precipitation." 33 C.F.R. § 328.3(c)(5). To know that, I have to know whether it has flow "in a typical year," 33 C.F.R. § 328.3(c)(12), which is further defined as "when precipitation and other climatic variable are within the normal periodic range (e.g., seasonally, annually) for the geographic area of the applicable aquatic resource based on a rolling thirty-year period." 33 C.F.R. § 328.3(c)(13).


Easy. Right? I've been working CWA jurisdictional issues for about 30 years, and I didn't know where to start, short of hiring a consultant, which my client likely can't afford, and I doubt many consultants have figured this one out yet. I spoke with a contact at the Corps, and he said that the Corps' Engineer Research and Development Center (ERDC) is developing an online tool to help people determine which streams might be intermittent. Also, USGS, is developing a probability-based tool to figure out what a rolling 30-year average flow looks like. The Corps is also considering looking at macroinvertebrates as another tool to figure out intermittency.


None of these complex tools, however, will tell you whether a particular stream is intermittent. They're just tools. You'll still have to make judgment calls and get into arguments with EPA and the Corps if they disagree. There will likely be guidance documents coming out, which will further complicate the issue with more detailed tests, benchmarks and considerations. (Note the new guidance rule just went into effect, making it harder to do guidance; see my May 19 blogpost for more). It will be interesting to see how the agencies end up interpreting this conundrum they've created, and how much litigation will ensue.


Looking at this new rule from the field, it's far from clear what streams are covered under the CWA.



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