Evaporation. It's a word I think about a lot these days.

Massive quantities of New Mexico's precious water are silently disappearing into the sky from our lakes and rivers – especially from the Elephant Butte Reservoir.

This is not a new insight. It is well recognized, if imperfectly understood. A number of studies have been done to attempt to quantify the water lost to evaporation from Elephant Butte. It turns out to be quite a scientific challenge to figure this out. The studies do not agree on a number – but whatever it is, it's really big.

A study by New Mexico State University, published in 2004, says evaporation from the lake is estimated to be roughly 250,000 acre-feet per year, as much as one-third of the approximate average inflow. That is based on an annual inflow ranging from approximately 114,100 to 2,831,000 acre-feet per year, averaging roughly 900,000 acre-feet per year.

A 2003 Bureau of Reclamation study says: "Assuming the reservoir occupies half of its potential surface area, the annual losses … can be expected to be about 66,000 acre-feet. By way of comparison, the annual releases from the reservoir are on the order of 800,000 acre-feet. Depending on the annual climate and the size of the reservoir, the amount of water lost through evaporation for just the Elephant Butte reservoir can be expected to range between 8 and 20 percent of the amount of water released from the reservoir for use downstream."

One observation notes that the water is not "lost" but is contributed to the natural cycle. These days, as we know, the natural cycle is not cycling back enough to New Mexico. What goes up here does not come down here. Maybe there is a reason that Nature does not usually create big lakes in hot deserts.

Are there solutions? Can that water be saved?

An intriguing proposal was made in 2003 to preserve all that water. The idea was to bank the water underground before it reaches Elephant Butte. Somewhere farther north, catch the amount of water estimated to be lost to evaporation each year and pump it down into the aquifer beneath Albuquerque. Then distribute it out to users throughout the Rio Grande Basin.

There were two catches. First, it would reduce Elephant Butte Lake to a series of puddles, which would no doubt make the plan unacceptable to the thousands of New Mexicans who use the lake for recreation and the communities that depend on their tourism dollars.

Second, the proposal came from a private company and was based on privatizing the rights to all that water. The proposers were asking for 400,000 acre-feet per year, based on their estimates of the evaporation from Elephant Butte, Caballo and Cochiti lakes. The company would own the rights and sell water to users.

This company, called Lions' Gate, would invest in the necessary infrastructure only if it could make money – presumably lots and lots of money from permanently owning those massive water rights. But the idea of allowing a single private corporation to control all that water was shocking – apparently not only to me but to every public entity that had potential jurisdiction.

Somewhere between the courts and the regulatory agencies, the proposal was quashed, and good riddance. But the technical concept seems to make sense. What if banking the water underground would work?

This summer, Elephant Butte Reservoir is reportedly down to – I can hardly bear to write this – 3 percent of its total capacity.

If the drought – as some scientists have predicted – becomes the new normal, and the lake loses its attractiveness as a weekend destination, alternative solutions may become less politically unacceptable. This one – with control remaining firmly in public hands -- should be at least worthy of evaluation.

Merilee Dannemann is an independent public policy professional in Albuquerque. Contact Merilee Dannemann through triplespacedagain.com.