Where does our water come from?
by Lawrence "Larry" Vincent
July 3, 2008
For generations our area’s acequia systems have been the lifeblood of rural living and a
cultural heritage treasure. Water is a critical natural resource in our area and southwest
region in general due to its impor-tance (everywhere) and its scarcity (here). The more
scarce a resource is the more valuable it becomes.
As population and economic activity grow, so does the demand for water. Where does
our water come from? The answer brings on another question. How far back or how deep
do we want to go in our thinking?
The earth was “born” with a finite amount of water (though we possibly get a tiny bit
from meteors) that has its origin in the solar system and beyond. Water is made of
hydrogen and oxygen, the latter generated through nuclear fusion in mas-sive stars that
preceded our sun’s formation (the sun is our closest star).
Fortunately this combina-tion of hydrogen and oxygen is stable. It goes through solid,
liquid and gaseous states without changing its composition. It’s always H2O. We’ll leave
the chemistry and astrophysics at this point and move on to our thinking in terms of
natural resources, their importance, use and management.
The water for our acequias comes from our watersheds which act as giant sponges that
soak up atmospheric water — rain, dew and snow — and gradually release it in our
mountain streams. Most watersheds are covered to a large extent by forests that play a
major role in the “sponge effect.”
The “sponge” is a combi-nation of vegetation, animals and soil. Soil, along with climate
and topography (altitude, slope and aspect), is a deter-mining factor in the vegetation.
Climate, soil and topography make up the habitat of the for-est. Vegetation, specifically
the forest, can be manipulated by human intervention through management practices such
as thinning.
The idea behind this discus-sion is to consider watershed management in the context of
natural resource management. The main concern is sustain-ability, which is vital to our
survival. One consideration is whether to protect or actively manage a watershed
(protection is also a form of manage-ment).
In the first case we must be aware that protection may not guarantee sustainability. Let’s
consider a forested water-shed, which could be any of ours in the area. I would like to
consider San Cristòbal not only because it’s my home, but because it is small enough to
be taken as a sort of model. Red River or Hondo would be much more complicated due to
size and also human com-plications since they are inhab-ited watersheds. We can think of
the watershed as a “producing area” and, in our model, the San Cristòbal valley as a
“consuming area”.
In watershed manage-ment, as in any other resource, we start by formulating pol-icy,
objectives and goals and develop a management plan. Generally speaking, we have two
main elements to consider. The first is managing the vegetation, meaning a form of forest
management. The sec-ond is the possibility of engi-neering structures to regulate flow
(dams and releases) or by stabilizing erosion-prone areas that require geologic and
engineering expertise and money. We will concentrate on the forest management aspect.
What could we do to main-tain stream flow or even increase it? Sustainability demands
a healthy forest, so the first consideration is trying to keep the forest healthy. Thinning
can be done for for-est health and also possibly to increase stream flow or at least
regulate it through manipulation of the snow pack. One of the effects of trees is to
inter-cept snowfall in the crowns, which increases the amount of snow lost to sublimation
(solid state to gaseous state) before it can accumulate as snow pack.
Theoretically we can have a better snow pack by not having too thick a forest. On the
other hand, a forest that is too sparse will expose more of the snow pack to sunlight and,
again, result in loss. There should be an optimum forest density that will maximize the
amount of snow retained to feed the streams and our acequias.
A major difficulty is that much of our watershed forest is pretty much inaccessible for
thinning. The economics of it are going against us. It simply costs too much. However,
how much is water worth? Think of the Lama watershed and the effect of the Hondo fire.
Could something have been done in forest management to mitigate the damage, to reduce
the intensity of the fire, even before it got to the Lama water-shed? Or might the fire
possibly improve water production later on?
Again, there are no easy answers.
Lawrence (Larry) Vincent is involved in the natural resources program at UNM-Taos.
Vincent has a Ph.D.degree in ecology and bachelor’s and master’s degrees in forest
management.
Megan Avina
Acequias are the lifeblood of area communities, but how does water get there?
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Copyright (c)2008 The Taos News 07/03/2008