This comment made me curious is such a thing actually happens.

As it turns out "greenmailing" is a thing, but not from environmental groups. Here's what claude found for me:

<ai> The concern isn't baseless—there are documented cases of parties using environmental law as leverage, particularly California's CEQA. But empirical studies show only ~13% of such lawsuits actually come from environmental groups; the majority come from labor unions, business competitors, and NIMBYs hijacking environmental review for unrelated purposes. In this specific case, WaterWatch has a 40-year track record on Oregon water issues and the concerns about fish habitat are supported by the Confederated Tribes of Warm Springs—so the 'thinly veiled shakedown' framing doesn't really fit </ai>

I hope doing that research didn't spend too much water!