• Mark Ryan

EPA/Corps WOTUS JD Tools

Yesterday, I wrote about the difficulty of determining whether a stream is intermittent or ephemeral under the new WOTUS rule, and I mentioned some computer models that are under development at the agencies.

If you follow the link below to EPA's website, you'll be told they're "under development." I've spoken with agency people who have test driven beta versions of the models, so they do exist. When we'll see them available to the general public is an open question.

It will be interesting to see if the models are open-sourced so that members of the public can see the assumptions and algorithms used to perform the calculations that predict flow characteristics in streams. I worked a lot with computer simulations for stormwater and TMDLs when I was at EPA. Knowing the assumptions the modelers make is key to understanding the accuracy of the model. No computer simulation is perfect, but some are much less perfect than others. It all depends on how they're written, and field tested.

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