A reminder that stormwater isn’t free water

There is a natural desire in water-short communities to capture and use stormwater. But a brewing feud between the state of New Mexico and the U.S. Environmental Protection Agency is a reminder that tweaking the stormwater management system is not without consequences, because the water you’re capturing would otherwise be going somewhere and doing something.

At issue is a new EPA stormwater permit for the greater Albuquerque area intended to improve water quality in the Rio Grande. Stormwater, especially from New Mexico’s summer thunderstorms, washes all kinds of crap into the river. This rightly concerns the EPA, which is charged with keeping crap out of rivers. But the new stormwater permit, according to a Feb. 26, 2015 letter from the New Mexico Interstate Stream Commission to the EPA, pursues this goal in part by reducing the amount of water that gets to the river.

The ISC also plays the Endangered Species Act card, arguing that reduced summer storm runoff reduces the amount of water available to meet flow targets for the endangered Rio Grande silvery minnow:

While this specific conflict – a federal stormwater permit – is narrowly focused, this raises a broader issue about the way we think about stormwater here in the Rio Grande Valley of central New Mexico. The Middle Rio Grande Regional Water Plan, for example, proposes to enhance stormwater capture as a water management strategy. My University of New Mexico colleague Bruce Thomson has long argued that we need to recognize that water management approaches like this are entering into a zero sum game – water captured before it hits the river (stormwater, treated effluent) is less water in the river. From a note he send to water colleagues this morning (quoted with permission):

For decades folks have had their eye on stormwater as the untapped resource that was going to save us all from future water shortages. Stormwater collection is in the 2004 MRG Regional Water Plan. The North Diversion Channel goes right past the Water Utility Authority’s treatment plant and they’ve had conversations about diverting storm water down the hill to their plant. And a topic at all of the local & regional water meetings is about repealing the 96 hour rule to allow folks to capture and store stormwater. The reason is simple – nobody has claimed stormwater or has rights to it so everybody’s first thought is we can see it, it’s right there, we might as well take it and use it.

This letter from the ISC is the first formal declaration that I know of to throw down the gauntlet and officially declare that that water serves an important role in the state’s water balance. There are going to be some wonderful battles to watch between the environmentalists, state & federal regulators, water rights holders, water planners and others as they begin to realize they can’t do anything that will impact stormwater flows.

Here’s the full ISC letter:


  1. Joe – Good question, thanks. The 96 hour rule is a state rule that restricts flood control system operators to holding water for a maximum of 96 hours before it gets released back into the stream or river to which it was headed before the flood control dam blocked its path. It’s intended to allow flood protection against a big pulse, but to ensure that the water gets back on its way downstream as quickly as possible.

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