Is Colorado violating the Endangered Species Act?

Water issues on the Rio Grande just got more interesting.  The environmental group WildEarth Guardians recently gave Notice of its intent to sue the State of Colorado for violating the Endangered Species Act.  Guardians alleges that Colorado is violating ESA section 9, which makes it illegal for any person to “take”–basically, kill or harm–an animal protected by the ESA.  The key species involved here is the Rio Grande silvery minnow, the last wild population of which lives in the Rio Grande in central New Mexico.

Guardians argues this:  silvery minnows need certain flows in the Rio Grande, especially high flows in the spring, to survive and reproduce.  But flows in the river have been inadequate for the minnow in recent years, largely because water uses within Colorado take too much water out of the river, especially in dry years.  The letter alleges that Colorado water uses (for San Luis Valley irrigation) have taken as much as 98 percent of the natural flows of the Rio Grande at any given time, and the resulting low flows have taken silvery minnows.  And because the State of Colorado administers water rights under state law, the State is responsible for that take, violating the ESA.

This would be an unusual case, but not a unique one.  Most ESA cases involving harm to protected species are brought against federal agencies, under a different part of the law applicable only to them.  There have been some similar cases to this one, however, where courts have held that state or local governments caused take.  Notably, a federal court in Texas recently found that inadequate water management by the State of Texas took endangered whooping cranes by drying out their winter habitat.  (That decision has been stayed and is now on appeal; watch this space for further developments.)  These cases establish that state governments may violate section 9 if they allow private activities that result in take.

That said, this case would not be a slam dunk–more like a contested 3-pointer.  Guardians would have to overcome serious factual and legal challenges to prevail against Colorado.   On the facts, they would have to show that water use activities within Colorado caused actual harm to actual minnows miles downstream in New Mexico.  As to the law, they would have to show that Colorado has enough power or control over those water uses to make the State (rather than the users themselves) responsible for any take they cause.   Guardians could expect a fierce battle on both points.

Colorado is likely to raise another argument:  that its water uses are fully legal under the Rio Grande Compact, a Congressionally-approved interstate agreement that allocates Rio Grande water among the States of Colorado, New Mexico, and Texas.  Such compacts impose obligations on states that are enforceable in the Supreme Court.  Compacts can limit water uses in an upstream state, even if those uses would be legal under the laws of that state.  But can the ESA limit water uses in the same way, even if those uses would be legal under a compact?  A case against Colorado may answer that question … or it may not.  If Guardians can’t show that Colorado violated the ESA, there is no conflict with the Rio Grande Compact, and no need to decide if one trumps the other.  Colorado’s uses under the Compact would be safe; the minnow might not be so fortunate.