SAFFORD — By 1916, large-scale erosion affected the San Simon Valley — a place described by some in the 1880s as a rancher’s paradise with plentiful grass. The issue gained some national attention in 1919, in a report to Congress titled Gila River Flood Control. However, no action was taken in the valley until the Depression era.
Starting in the 1930s, as one of many national work projects, a number of erosion control structures have been built in the 1.25-million-acre San Simon Valley. A century after Gila River Flood Control (aka the Olmstead Report) was published, just how many structures exist and in what condition is a question that greatly interests University of Arizona Cooperative Extension Director Bill Brandau. A recent inventory by Brandau and students from his Eastern Arizona College watershed class estimated more than 4,000 erosion control structures in the Upper Gila River watershed.
“I have proposed for years to look at this system out here, make an evaluation of significant structures and decide which ones are in need of maintenance, which ones are most important and which ones we’ll just forget about,” Brandau said. According to Brandau, a similar analysis of drainages around Duncan is being proposed by Greenlee County.
“The San Simon watershed is probably the most significant source of sediment entering the Gila River. It has multiple drainages protected by two large structures and many side structures, some of which are not maintained,” he wrote in a 2013 Courier article.
The Safford Bureau of Land Management Office works to maintain the valley’s 18 large dams, but hundreds of smaller structures dot the area. The Cooperative Extension is working with the BLM and Gila Watershed Partnership on a plan to assess those structures, a number of which were 1930s Civilian Conservation Corps (CCC) projects.
“Nobody knows they’re out there. There are hundreds of them, and they’re approaching 70 to 90 years old,” Brandau said.
In the 1930s, two national agencies, the Soil Erosion Service and Grazing Service (now known as the Natural Resource Conservation Service and the BLM, respectively), conducted an inventory of the area; then the CCC crews went to work.
“There was thought that we had a problem out there and needed to learn how to fix it,” Brandau said. “It became a center of attraction for lots of people to do conservation work. The whole idea was to slow erosion and try to get it back to some state that was better than these eroded areas.”
Several factors are thought to have contributed to the San Simon Valley’s dramatic erosion, which continues to threaten dams and local roads: overgrazing by cattle in the 1880s, the area’s fragile soils, drought followed by storms, an 1887 earthquake in northern Mexico, and concentration of water flow in the San Simon River and its tributaries by the construction of railroads, wagon roads and channels.
The 1919 report decried a channel Solomon farmers dug to divert San Simon River water away from their property and into the Gila River. According to author F. H. Olmstead, the resulting concentration of flow carved out a 60-mile chasm 600 to 800 feet wide and 10 to 30 feet deep in many places. It was, said the report, “an illustration of what a half-dozen unthinking men can do to create waste.”
Paraphrasing the words of Mme. Roland, a woman executed in the French Revolution, Olmstead wrote: “ ‘Oh, Liberty, how many crimes are committed in thy name!’ ”
As the next step in tackling erosion, larger dams were introduced to the valley from 1940 to 1980, starting with the Goat Well Drop Structure. Built in 1940 by the CCC and Soil Conservation Service to stop erosion along Slick Rock Wash, the 79-year-old structure is now maintained by the BLM, which repaired it in 2010.
The purpose of such drop structures and dams, including the smaller, older ones, was to slow water enough that it drops most of its sediment load, building channels back up.
By 1989, the $1.3 million San Simon Barrier Dam had trapped 5 to 6 million tons of silt and regraded the channel for around six miles upstream. Completed in 1980, it was the second dam built on the San Simon River itself. The first, the San Simon Fan Structure, was built by the Soil Conservation Service in 1953. The fan had trapped 19 million tons of silt by 1989, regrading the channel for more than 10 miles.
“What we have created is a sediment bank. We’ve stored millions of cubic yards of sediment behind all these structures. If they’re not maintained, they will eventually start breaching, and all that sediment will start moving downstream again. And they aren’t being maintained on any large scale,” Brandau said.
The larger dams have not always worked perfectly. The HX Dam north of Bowie was breached by unknown causes in 2014, resulting in a two-year repair project by the BLM; the San Simon Fan washed out in 1954 and was rebuilt the next year; and the Whitlock Retention Dam, built in the late 1960s, washed out three times before local rancher Pete Brawley lent a hand.
After its third washout, Brawley, now retired, and his ranch hands fenced off the bottom of the dam, brought in cattle, used a Caterpillar to push up soil, spread hay atop the soil and left the cattle overnight to trample down the surface. Afterward, the Whitlock held firm.
That was hardly the end of Brawley’s contributions in the San Simon Valley. Brawley, who served as the Gila Watershed Partnership’s first chairman, built more than 100 erosion control structures in the area. In one project, he and his crew worked with AmeriCorps members to place check dams in a local canyon from the top down. Brawley said the reduced rate of water flow benefited vegetation.
“It’s more important how you hold water up than how you turn it loose,” he said. “Had they (the CCC and other agencies) started from the top down, it would have worked better at reducing the rate of water flow.”
With assistance from the BLM and Graham County, Brawley and his men also built a series of rock and wire gabions along roads on his ranch in order to prevent washouts by allowing water to flow off the roads quickly. Before those gabions were built, the roads could not be traveled without four-wheel drive.
“There’s not been enough clear understanding scientifically to determine the significance of the loss of all these structures,” Brandau said. “If Goat Well Drop washes out, where’s the sediment going to go? Downstream. It’s going to go right down the San Simon. It’s going to take time, — we’re talking decades — but eventually it’s going to get into the Gila River and end up in San Carlos Reservoir. That’s what rivers do; they transport water and they transport sediment.”
William Brandau contributed to this article.
This is the third in a series on erosion and erosion control in the San Simon Valley. Next: A closer look at restoration plans.