Groundwater News is Creepy
To cut to the chase, groundwater is precious and “leisurely.” The chief feature of groundwater is its astonishing lack of speed. “Out of sight” is also big in the setting.
In our region, water generally moves in the ground from the mountains, where it rains, to the rivers in the valleys, where it doesn’t. Typically the water down in the rock layers creeps along at much less than a snail’s pace.
Groundwater speeds are measured in inches or feet per year. A foot per year means water travels a mile in 52 centuries. A look at the world 52 centuries ago finds early signs of written history in ancient Egypt, long before the pyramids.
Since a spring day of that time, some groundwater has flowed one mile. You get the general picture.
Some rock allows a faster snail’s pace. Under Los Alamos, water seems to move in rock at more like a mile in 50 years. Cracks add further shortcuts.
Such remarkable slowness matters in more ways than you may guess. For one, the water is in the rocks long enough to leach strange things from them. In different parts of New Mexico, “nature’s additives” include arsenic, chromium, copper, lead, manganese and uranium, among others.
Towns test their drinking water to find which of these materials they have and how much of it, since too much of any kind is harmful.
Despite its slowness, groundwater can be pumped (gathered) from a sizable volume of rock at a reasonable rate. So we have wells, which supply 90 percent of the drinking water in New Mexico.
The rudiments of geohydrology (the science of groundwater) increasingly matter to the public. People begin to realize a well can gather water from quite a distance, as far away as someone else’s well field or the river. In New Mexico, this fact grabs attention like a missing horse. Concerns are sure to grow over who is pumping whose water.
The slow travel and deep pathways of groundwater also affect the spread of man-made pollution. A sticky question is, if wastes are dumped on or in the ground, how long before the bad stuff could show up in water wells or rivers?
Remember how groundwater creeps. Seeing no bad effects for three or five decades says little about the movement of wastes dumped in the ground.
The long-term risk or security of a water source is a guess when we don’t know what is happening underground, and people seldom look to see.
Until groundwater pollution pops up in someone’s water well or a river, the only way to track it is to drill test wells at wisely-chosen sites. The wells are not cheap, so their numbers are limited.
Data from the wells allow estimates about the general movement of pollution. As usual, complications confuse the picture. Rock layers are not uniform. They can begin and end in unexpected places. Cracks and fissures occur.
A rock layer that might otherwise keep pollution out of the groundwater can have secret passages. Thus pollution may wriggle with puzzling speed into surprising places,
The final point where speed matters is in cleaning groundwater once it is polluted. Notable concerns include septic systems, gas station tankage, oil drilling wastes, wastes from the local lab, dairy herds, dry cleaning solvents and road salt.
Methods exist for cleaning pollutants from groundwater and better ways are worked on constantly. Some techniques use various additives, such as “oxidants” that oxidize the bad stuff, detergents that help sweep it from rocks, and nutrients and microbes that make a bug feast of bad stuff.
That’s right, certain bugs would rather dine on pollution than coq au vin. Bugs are crazy, but helpful. Yet these methods take years to stop pollutants from spreading.
Slowly the long story reaches us. Halting pollution at the start is much simpler, cheaper and swifter than trying to deal with it down in the rock layers that supply our water.
