Deep Ground Water, Desalination, and Unintended Consequences: Water Policy Vacuum

Just when I was wondering what to post today, John Fleck sent me this link to a 16 August 2008 Albuquerque Journal editorial about pumping and desalting deep ground water. [Note: You will have to click on a free trial premium pass and view a commercial to access the editorial].

The sage folks at the Journal have done us all a service, exposing a flaw in New Mexico water policy (and those of other Western states, no doubt): what do you do about the pumping of deep ground water that, because of its presumed isolation from surface water bodies ('non-tributary') is outside the purview of state water law? Any non-tributary water you pump is yours without having to obtain a water right or worrying about offsetting stream depletion due to pumping. 'Produced water' or 'production water', a by-product from oil and gas wells, is included in this category.

When people talk about non-tributary "new" sources of water, I suspect they are referring to this "produced water' or other deep ground water beyond the grasp of states' water laws.

Just a word about ground water before continuing. The concepts of "tributary" and "non-tributary" seem straightforward but can be fraught with uncertainty when applied to ground water. All flowing ground water ultimately discharges to a surface water body. But the amount time it takes to do so can range from a few tens of minutes to millions of years. So when a state's water law talks about "tributary" ground water, what is the time frame? A human lifetime? 500 years?  

The water laws of many states do not treat ground water very well. They were essentially designed for surface water, then jury-rigged for ground water.

As I was leaving New Mexico in 2006, there were plans afoot to quench the thirst of the growth in the greater Albuquerque area by pumping deep brackish (non-potable) ground water and treating it to drinking water quality by desalination.  

Since New Mexico won't have a sea coast for another 50-100 million years, the above illustrates a fact: desal is not just for coastal areas, but can be employed anywhere you have non-potable (brackish, salty) water with high levels of Total Dissolved Solids (TDS). As a references, sea water has a TDS of about 35,000 mg/L, most of which is due to the chloride and sodium ions. I have heard of ground water with TDS as high as 400,000 mg/L (geothermal "fluids" in the Imperial Valley area of SoCal). That's more like "rock soup" than water.

New Mexico has plenty of brackish/salty ground water. There is some in the Albuquerque area, but the largest trove of all is likely in the Tularosa Basin of south-central New Mexico, where the White Sands Missile Range is located (see red dot on map). The basin is about 6,500 square miles (almost 17,000 square kilometers), and is home to the Brackish Groundwater National Desalination Research Facility (BGNDRF). I have heard estimates as high as several hundred million acre-feet of brackish/salty ground water in the basin. All you have to do is pump it out and desalt it.  

The Journal editorial specifically mentioned operations west of Albuquerque in the Rio Puerco Valley (see the blue line at the lower left-hand corner of the land surface of the figure, from Gayla R. Corley). One operator wants to produce 110,000 acre-feet per year, and Sandoval County, a fast-growing suburban area, wants to produce 12,000 acre-feet per year.

The above cross-section is an overly simplistic representation of the valley-fill aquifer in the Rio Grande Valley. Recent work has indicated it is far more complicated than depicted, but it will suffice for our purposes.

Back to the editorial:       

       The mining of deep brackish water will inevitably become a statewide issue; huge reserves have already been identified in the Tularosa Basin.
       It's a “free-for-all,” State Engineer John D'Antonio says of a deep-water mining boom he finds himself nearly powerless to control. Unfortunately, a free-for-all is what happens in a policy vacuum.
       Because few people imagined deep brackish water would ever come to the surface as anything but waste “production water” in oil and gas drilling, state water law exempts it from the purview of the state engineer, who administers water rights in New Mexico. 
      Existing law offers no tools to regulate deep pumping, though the state could step in if it were shown the operations were threatening fresh water aquifers, conventional wells or causing environmental damage. That could well translate into after-the-fact, remedial action.

The editorial rightly indicates that pumping from deep aquifers could contaminate and drain water from shallower freshwater aquifers. Existing water rights holders could be affected. It could also induce land subsidence. 

The little figure is a simple illustration of a two-aquifer system. Imagine that the deep well is in the non-potable brackish water aquifer and the shallow well is in the freshwater aquifer. Even though the two are separated by a low-permeability layer and perhaps by thousands of feet, the effects of the pumping in the deep aquifer may induce leakage from the shallow aquifer. Keep in mind that effect could take many years before it manifests itself. The amount of time will depend upon the properties of the aquifers and the low-permeability layer, the distance separating the aquifers, and the pumping rate. There are two different effects caused by pumping: one is a pressure response, which occurs relatively quickly (travels at about the speed of sound in the rocks/sediments), and the other is a volume transfer of water, which takes much longer. Complicated, but not rocket science.

And don't forget the waste produced by desalination. This is not within the purview of state engineers;  state environmental or mining agencies handle oversight here. But let's see how much waste could be produced.

If you remove 10,000 mg/L from 110,000 acre-feet of water each year, that is about 1.5 million tons (1.35 billion kilograms) that has to be disposed of every year. Since volume is more important than weight or mass in terms of waste disposal, let's assume the waste has the density of solid halite (mineral form of NaCl), which is about 2170 kg/cubic meter.  So that waste will occupy a volume of  622,000 cubic meters or about 22 million cubic feet per year. That is a cube about 280 feet on a edge, or about 500 acre-feet of waste per year!  That's a conservative estimate because I assumed the waste could be treated as solid halite, when in fact it will be more like a granular material, similar to table salt.

The editorial concludes:      

              The state engineer has sought regulatory authority over this water in the past two sessions, but lawmakers have never gotten the bills to the floor for a vote. 
              The West's entire water-law tradition argues against unregulated, unlimited access by new claimants.
       The Legislature cannot sit on its hands, ignoring an an issue that could well shape the state's future. It shouldn't be too hard to write an exemption for oil and gas drillers into a larger framework designed to give policy makers — not water speculators — the final say over New Mexico's precious water resources.

Time for the folks in New Mexico to step up and give D'Antonio the authority to regulate this 'new' source of water. Other states will be looking in, so do it now, folks.

By the way, let me shill for a conference that Todd Jarvis and I are co-chairing in two months: International Conference on Nonrenewable Ground Water Resources. This conference will address some of these very same issues.

"Before millions are invested in a California Gold Rush-style melee in the Rio Puerco Valley or Tularosa, the Legislature should address the issue. At the very least, lawmakers could lay the foundation for rational policy governing the use of this untapped resource." -- Albuquerque Journal editorial 

Comments

[Shane]

The advanced desalination systems are designed to restrict the amount of wastage, use of energy and impact on marine life. And in the coming years, the hardware is only going to get better. As it is, desalination is inevitable, so worrying about its disadvantages is not an option. Let's be hopeful that the components used for the future watermakers are more energy and cost efficient. One such name which seems to be hitting the right note is: https://www.ampac1.com/products/seawater-desalination

[Joefucious]

I look forward to the fossil salt.

[Todd]

The journal Water Policy will be publishing an idea on how to govern deep groundwater using the Law of the Sea as a model for the Law of the Hidden Sea by Elena Lopez-Gunn of the London School of Economics and Todd Jarvis. Treat *deep* (greater than 300 meters) groundwater part of the global commons like the oceans? Heresy!

[David Zetland]

Good News: "Fossil Salt" (made in USA!) will be very cheap at Whole Foods. :)