Wednesday, January 2, 2013

Enhancing the Management of Arizona's Aquifers - an Alternate Proposal to ADWR

Arizona Department of Water Resources (ADWR) recently floated a proposal to change the formula is uses to grant groundwater credits to entities that artificially recharge renewable water into aquifers as a way to permit additional groundwater pumping.  The state recharge program is a somewhat complicated scheme that I can't explain in detail right here, but you can get lots of other information at ADWR's website here.  This proposal is being made as part of the 4th Management Plan process - a once-a-decade planning exercise that is intended to get Arizona's Active Management Areas to Safe Yield by 2025.

The gist of the proposal is that it would reward entities that locate their recharging activities closer to where they are actually pumping out groundwater.  A worthwhile endeavor to be sure. 
It does this by tweaking a policy that was designed to provide a distinct benefit to our overworked aquifers by mandating that a small percentage of water that is recharged remains in the ground - known as the "cut to the aquifer".  Currently, when water is recharged to be recovered at a later date (not within the same year) 5% of that water must remain in the ground.  There are differing rules that depend on how the recharge occurs, but I'll let ADWR explain that. 

What they are proposing is to have an adjustable level of that "cut to the aquifer" that depends on whether you are conducting your recharge in ways that promote more sustainable aquifer management.  If your pumping occurs within one mile of where you are recharging you get full credit for what you recharge.  If those two activities are located more than one mile apart AND in separate hydrogeologic sub-basins the aquifer gets a 20% cut.

It sounds good on the surface but there have been some rumblings from the Arizona water management community.  Alan Dulaney, with the city of Peoria, near Phoenix, had this comment in a recent newsletter from Arizona Hydrological Society:

By moving in the direction of administrative simplicity, ADWR is taking the wrong approach.  Stabilizing groundwater declines is a moving target, and broad simplistic approaches will not work.  What is needed to address the imbalance problem is not a spreadsheet, but focused hydrogeological studies on each situation to understand how the water is introduced into the aquifer and what happens when specific pumps are turned on and what is likely to occur over time, followed by regular evaluations based on monitoring data.  We need more hydrology, not less.
The Arizona Water Bank (a state agency loosely connected to ADWR) released some comments of their own at their most recent meeting. Their comments are focused on the difficulties this proposed idea could have on the Water Bank's operations, which have slightly less flexibility than those of many other water-recharging entities.  I think ADWR's proposal completely fails to consider the type of recharge an entity like the Water Bank is conducting.

Basically, ADWR has proposed an idea that, while appearing administratively simple, is also very susceptible to not meeting the objectives they have set out for that idea.  That's because, as with most aspects of water management the devil is in the details.  And the details of hydrogeology are very complex.

So I have an alternate idea to propose that I believe might better achieve those goals, but as Alan Dulaney pointed out, might require some more extensive data collection but mostly would require some genuine analysis of what is actually occurring in our aquifers and how they are affected by both pumping and recharge:
Stay with the idea of a moving scale for the cut to the aquifer associated with water storage, but instead of basing it on distance between recharge and pumping base it on something that actually reflects the overall health of the aquifer - water levels.  Any entity that relies on recharge of their renewable water in order to permit recovery of that water at a different location would be required to collect water level data from certain indicator wells within their service area to gauge the impact their pumping is having.  This is already being done (pretty much), so nothing earth shattering about this.  The new part I'm proposing is that the cut to the aquifer that entities pay when they recharge water would be based on a target number for water level decline in those indicator wells.  This would probably need to be set for each sub-basin, possibly for each water provider.  If that target is exceeded in a given year the cut to the aquifer is increased.  If they reduce it, the cut gets reduced. 
This would be somewhat similar to the idea of a pump tax that is based on depth to water - increasing as water levels decline.  There could be complicating factors for certain water providers.  If there are other pumpers within their service area that might affect water levels they run the risk of being punished for someone else's pumping.  The won't like this, but could resolve it with some classic Coase-ian bargaining.  It's not a hard and fast rule.  It's an economic incentive that will encourage entities that pump groundwater to limit water level declines in the aquifers they rely on - this is what ADWR is basically trying to get at by tweaking the rule.  It will encourage them to manage their available water resources in ways that take maximum advantage of their renewable supplies. 

I would love to hear your feedback on this idea.  Is it workable?  Please post a comment or send me an email.

1 comment:

Tom said...
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