Any discussion of Coolidge Dam simply can't be complete without a decent overview of The Gila River. The total watershed area of The Gila River is 58,200* square miles but "only" 12,886** square miles are located above Coolidge Dam. The confluence of the East and West Forks are widely considered to be the point of beginning of The Gila River itself. The river stretches 259 miles between that confluence and Coolidge Dam.
The true birth places of The Gila River could also be considered the heads of The East, Middle and West Forks of The Gila. The length of those streams could add another 40-50 miles to the 259 mile primary reach of The Gila about Coolidge.
River runner, hydrologist, engineer and author Jon Fuller provided the river mileage information above. Fuller's book "Gila River Elegy: Paddling America's Most Endangered River" is The Best and Only accurate source of information about the current nature and characteristics of the entire Gila River from its source to the Colorado River at Yuma. However, various private, non-profit and government websites provide a plethora of information about The Gila River.
Above is a simplified depiction of the Gila River watershed above Coolidge Dam.
The far Upper Gila River Watershed is colored orange above. The San Francisco River Watershed contributes nearly as much area and runoff as does the Gila River watershed. Together the Gila and San Francisco Rivers form the mainstem Gila River heading into the Arizona heartlands.
Source of graphic: https://www.southwickassociates.com/gila-and-san-francisco-rivers/
Prior to the 1880's, The Gila River and its tributaries produced relatively stable runoff regimes.
Massive over grazing in the 1880's forever changed all aspects of The Gila River's vast watershed. The Upper Gila was particularly hard hit by the grazing free-for-all that reigned in the 1880's. Once the land was stripped of stabilizing native vegetation, snowmelt and summer storm runoff reached dizzying proportions and locomotive speed. The Gila River channel in places went from barely 200 feet wide to as much as two miles across. A stream that once provided clear, life-giving perennial river flow became widely known as the "World Muddiest River." (Ross Calvin* 1946 Pages 135-153)
The 1891 Flood is by consensus the biggest, baddest ever to molest The Gila River. No precise peak flow has ever been pinned down for 1891 but ballpark estimates range anywhere from 150,000 cfs in the upper watershed to 300,000 cfs in the low Gila River below Phoenix. Gargantuan floods also took place in 1905-06 and 1916.
Even today, water managers in charge of releases from Coolidge Dam consider the Gila River a fickle watershed. They generally tend to count on reservoir rises when it rains on snow in the New Mexico mountains. Those water managers have become so gun-shy over decades of dealing with the feast or famine Gila River runoff that they take the reservoir level on January 1 each year as their management baseline.
Even today, water managers in charge of releases from Coolidge Dam consider the Gila River a fickle watershed. They generally tend to count on reservoir rises when it rains on snow in the New Mexico mountains. Those water managers have become so gun-shy over decades of dealing with the feast or famine Gila River runoff that they take the reservoir level on January 1 each year as their management baseline.
Source of flood flow figures above:
and: https://pubs.usgs.gov/of/1955/0170/report.pdf
https://drive.google.com/file/d/1VZXudmN5T0eoa0dW9yutKE8go1jg3lcU/view?usp=sharing
A substantial wilderness-style river run exists between Coolidge Dam and Winkleman. It is called by various names: San Carlos Canyon, Box Canyon, Needle's Eye, and others. Coolidge Dam was sited at the head of this canyon, the last major such canyon along the 650+ miles of The Gila River. The Hayes Mountain form the northern portion of this area and the Mescal Mountains the southern sector. For those few intrepid river runners who have paddled that stretch, it is considered to be one of the finest inland desert runs in The Southwest.
Canyon graphic source: https://www.researchgate.net/figure/Location-map-for-the-San-Carlos-Canyon-reach-of-the-Gila-River-Arizona_fig44_322765638
The Gila River often leaves Coolidge with nothing to do. The reservoir has been dry approximately 20 times and fully overflowing only once in 1993. The reservoir has been full several times but generally is far from full. As of March 5, 2022, so-called San Carlos Lake contained 30,353 acre-feet of water was was roughly 3-4 percent full.
People have been writing about the Gila River for almost 400 years. The amount written about the Gila has only increased over time. If legal documents and lawsuit filings are included in the "writings" of The Gila River, there would be enough pages to fill a medium-sized city library. to full discuss The Gila River and its watershed is far beyond the scope of our simple blog. However, we will continue to add interesting links to this page. Here are a couple to get you started:
https://e360.yale.edu/features/once-a-rich-desert-river-the-gila-struggles-to-keep-flowing
Here are a couple of fun facts about The Gila River watershed:
* The full Gila River watershed is bigger in area than 30 of the US states.
** The Gila River watershed above Coolidge Dam is larger in area than the combined states of Massachusetts and Connecticut. (12,886 vs 12,683)
Here are a couple of fun facts about The Gila River watershed:
* The full Gila River watershed is bigger in area than 30 of the US states.
** The Gila River watershed above Coolidge Dam is larger in area than the combined states of Massachusetts and Connecticut. (12,886 vs 12,683)
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| Copyright 2021 by Lori Bailey. All Rights Reserved. Used here with permission. |
Once upon a time, The Gila River was lined with mature, old-growth cottonwood and willow trees. With overgrazing and over-diversion of the river's scant water resources, invasion tamarisk trees took over many miles of river channel. In many places, the tamarisk grow too thick for humans to penetrate. Occasionally, those invasive trees will catch fire, either by natural or human causes. They burn hot and put on a spectacular show. We wrote an interesting comparison between the "flaming rivers" of the Gila and Ohio's Cuyahoga. To read it visit:
* "River Of The Sun Stories of The Storied Gila" by Ross Calvin 1946 University of New Mexico Press, Albuquerque 153 pages.
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