Can Life Exist After a Dam Silts In?

Lessons learned from Sabino Creek

Some day in the distant future,  the buildup of silt behind Glen Canyon dam will preclude the generation of electricity..  The Glen Canyon Institute has seized upon this fact and tried to mislead people into thinking that the sky is falling and we need to get rid of the dam NOW!   But I'm not so sure that panic and over reaction is an appropriate response. 

What is the present rate of siltation?  Can we prolong the life of the dam by allowing some of the silt to pass on through?  How long into the future will Lake Powell exist as a shallow lake?   What kind of new habitat will be created?  Will this new habitat function as an important wildlife refuge for thousands of years?  What has happened to other western lakes?  These are some of the broader questions I would like to contemplate.

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Silt creates habitat in Upper Navajo Canyon - Lake Powell

Sonar measurements show that at the current rate of siltation, Glen Canyon dam could theoretically fill up with silt in about 750 years.  This estimate assumes that all silt would somehow be trapped by the dam and that none would ever be allowed to pass on downstream (a purely hypothetical and simply non-sensible situation).    The reality is that we can and will do many things to mitigate the impact of siltation on Lake Powell.  It is not likely that we will every see the top of the dam silted in.  Water and silt will continue to pass through the dam for thousands of years and it is safe to say that Lake Powell will continue to function for thousands and thousands of years as a shallow recreational lake and an important wildlife refuge.

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    Beavers working new habitat in Upper Navajo Canyon                        New habitat in Upper Warm Creek - Lake Powell

You might be saying "How can this be true?  How can Lake Powell become the gift that keeps on giving?  The answer lies in looking past the rhetoric concerning silt and look at the reality of life in the arid west where water, silt and nutrients are valuable commodities.  You may not like dams but the reality is that water and "trapped" silt are gold and this moist fertile soil if left undisturbed long enough can create remarkably lush riparian habitat....sometimes reaching jungle proportions.

Lessons Learned:  A History of Sabino Dam

One of my favorite childhood places was lower Sabino Creek in Tucson, Arizona.  Our favorite picnic area by far was one that had big lush trees, sandy beaches, shallow water for swimming and plenty of snakes, frogs and salamanders to hunt down.  There was always a delightful waterfall downstream.  As a young boy, I had no understanding that this lush oasis was, in fact, man-made.  All I was a great place to play, experience nature and I wanted to go there again and again (which we did).  It wasn't until decades later that I made the connection with this magical place and the construction of Sabino Creek Dam.

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        Desert Vegetation surrounding Sabino Creek                        A section of Sabino Dam on Sabino Creek built in 1937

In 1933, Tucson's Chamber of Commerce proposed damming Sabino Creek to create a lake, suitable for boating, fishing and swimming. A road with nine bridges, now the main tram road, was built. Chamber officials issued maps showing the lake, but their dreams of a watery tourist mecca vanished when the federal government refused to subsidize the project.

A smaller dam was built downstream in 1937 by Emergency Relief Administration laborers (see above photo). Sabino Lake became an instant success:  Fishermen liked its stocked waters and swimmers splashed in it, until siltation made the lake too shallow over a periods of a couple of decades.. 

Today (even though the dam has since long silted in), a shallow lake still exists and a virtual jungle of lush growth has taken advantage of the rich soil trapped by the dam.  Large walnut, sycamore, ash and cottonwood trees now create canopied groves. Deer gather around the dam site to nibble on tender offerings.  Merry songbirds sing to each other.  A ringtail cat slips quietly away when hearing approaching footsteps.  Can this really be Tucson?  A rope swing can be found tied to a large tree branch hanging out over the lake which still provides plenty of opportunity for wet laughter....perhaps echoing the laughter heard a generation ago at the same gathering spot...albeit a much younger Sabino Lake.   

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Today's lush riparian habitat behind Sabino Dam (Sept 2000)

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