What is Granite Reef Dam?
Most dams are about storage. Granite Reef stores almost nothing. It’s a low concrete wall laid across the Salt River a few miles below the Verde confluence, northeast of Mesa, and its job is to lift the river just enough to pour it sideways: into the Arizona Canal on the north bank and the South Canal on the south. The big reservoirs upstream decide how much water comes down. Granite Reef decides where it goes.
That makes it the headgate of Scottsdale’s history. The Arizona Canal opened in 1885, and canal water is the reason anyone paid for desert land here at all. For its first two decades that water came off a timber-and-rock dam that the river kept breaking. The federal government’s answer, built from 1906 to 1908 by the brand-new U.S. Reclamation Service, was this concrete weir. The Salt River Project runs it today on behalf of the government that still owns it.
You can’t walk out on it. The north end sits on the Salt River Pima-Maricopa Indian Community, the south end faces Mesa, and the whole thing is a working water facility. What you can do is stand on the river a short way upstream, at a Forest Service picnic site, and look at where the canal you jog beside in Scottsdale begins.
How to see it
Use the Granite Reef Day Use Area. The Tonto National Forest’s Granite Reef site is the closest public ground. The Forest Service describes it as the picnic site nearest Mesa: on the Lower Salt, with non-motorized boat launching, shoreline fishing and good birding. It’s day use only, with no trailers, no motorized boats, no glass containers, and dogs on a leash. Getting there: take US 60 east from Mesa to Power Road, turn north, and follow Power Road as it becomes Bush Highway for about seven miles. It’s the first river site you reach coming from the west. By the coordinates the Forest Service publishes for the site and the published coordinates for the dam, the picnic area is about half a mile upstream of the weir. We haven’t confirmed which spots along the shore give a clear sightline to the concrete, so plan to walk a little.
Bring a pass. As of fall 2026 the Tonto Daily Pass is $8 per vehicle from a Forest Service office or retail vendor, or $12 at the on-site fee machine, which takes cards only. Interagency passes work too.
Stay off the structure. There’s no public crossing, and the canal intakes at each end are dangerous water. The north abutment is on Community land; treat it as you would anyone’s private property.
Go when the river is running. In a wet winter the pool above the weir is wide and fast, and you can understand at a glance why a timber dam lost every argument with it. In a dry June it can look like a pond. Either way, the tubing and wild-horse stretch of the Lower Salt is just upstream.
Then finish the trip in Scottsdale. Drive home and walk any stretch of the Arizona Canal Path, or the Crosscut Canal Path at the city’s south end. The water beside you passed through Granite Reef’s north headgates a few hours earlier.
The dam that replaced a dam
The fullest history of Granite Reef is a 1990s Historic American Engineering Record report, HAER No. AZ-51, written for the National Park Service by Tonia W. Horton of the SRP Research Archives. Nearly everything below comes from it, and through it from the Reclamation Service’s annual reports and the Phoenix papers of the day.
The problem. By 1903 the north side of the Salt River Valley was irrigated by the Arizona Canal, which took water from the Arizona Dam, a timber crib filled with rock. The river kept breaking it. In April 1903 Charles Walcott, director of the U.S. Geological Survey, wrote to the Interior Secretary that any serious Salt River project “should provide for a permanent diversion dam in the Salt River just below the mouth of the Rio Verde with one large main canal on the north side and one on the south side.” The farmers’ new Salt River Valley Water Users’ Association wanted the same thing. The April 1905 flood settled it. The Arizona Dam was damaged so badly that irrigation under the Arizona Canal was considered impossible.
The site. A Reclamation Service boring crew under George Hammond moved three miles downriver from its first test site to a place the papers called the “granite riffle.” The Arizona Gazette reported in January 1906 that the banks were “bull granite,” with outcrops reaching “clear across the river with only an occasional break.” Borings found bedrock 17 to 20 feet down. The crew drilled seventy-two holes before breaking camp in July 1906.
The money and the race. On January 13, 1906, the Interior Secretary allotted $375,000 for a diversion dam, headworks and the first two miles of new canal. In February the government bought the Arizona Canal system itself for $235,168, and the Reclamation Service’s Louis C. Hill and the Water Users’ Frank Parker filed nearly identical water notices for the new dam nine minutes apart. Construction by the government’s own crews was authorized on July 26, 1906.
The design. Engineer A. L. Harris drew an “overflow” weir, a dam designed to let floods pour over its crest, because canals at both ends ruled out side spillways. It was sized for floods of about 165,000 cubic feet per second. Fred Teichman designed the sluice gates that flushed sand away from the canal intakes, with eighteen regulating gates behind them feeding the Arizona Canal and nine on the south side. When finished, the Reclamation Service described “a rubble concrete weir 1,000 feet long, with a maximum height of 38 feet, a base 36 feet wide,” with an 18-inch concrete apron reaching 75 feet downstream.
The camp
Granite Reef was a work camp before it was a dam. Superintendent James W. Martin laid it out on the south bank in the fall of 1906: tents at first, then sheet-iron bunkhouses, an office, a store, a hospital, a school, a blacksmith shop and a powerhouse. The camp sat 28 miles from Phoenix and 12½ miles from Mesa, connected by a new government road and a daily stage. Common laborers earned $2 a day, less 75 cents for board.
The HAER report is plain about the rest. Segregation produced two camps. A separate cluster of tents “known to the workmen as Mexico” housed Mexican and Mexican-American families. The model mess hall’s two dining wings, the report says, “accommodated ethnic separation.” In May 1907 the camp added an ice cream parlor, with ice hauled from Mesa.
The engineering marvel was a Lidgerwood cableway. Its steel cable, about 1,600 feet long and weighing around 11½ tons, was hauled from Mesa by eighteen horses. It carried a cage that could move 35 men across the river in about a minute, instead of an hour’s round trip by footbridge. The first death on the job came during its rigging, when a cable rigger working mid-river lost his grip and fell. By May 1907 nearly 350 men were on the payroll. When a flood hit in October 1907, the cableway hauled machinery out of the riverbed in time to save it.
“There is water in the ditches”
The dam wall was finished in late May 1908, and the pool behind it, nicknamed Lake Martin for the superintendent, ran a mile and a half to two miles upstream. Locals talked about boating, fishing and a resort. On June 13, 1908, Phoenix’s mayor declared a holiday. In blistering heat, a crowd estimated at 1,200 to 1,500 watched Governor Joseph H. Kibbey start the machinery that raised the Arizona Canal headgates. The Gazette closed its story: “The cantaloupe men will not be at church this morning, for there is water in the ditches.”
The Reclamation Service’s books for the year ending June 30, 1908 put the dam at $539,100.09, plus $44,267.41 for new Arizona Canal headworks. The South Canal, which carried the south-side share to the older Consolidated Canal system around Mesa and Tempe, was finished in June 1909. Two months after the dedication, the Phoenix booster Dwight Heard wrote that the dam replaced “seven more or less temporary dams” and excelled “some of the world-famous structures of this character in India.”
A century of floods
The weir held. The apron below it didn’t always.
- 1919–1920. Between November 27 and December 10, 1919, water ran 7.65 feet over the crest at an estimated 102,000 cubic feet per second and destroyed a 500-foot section of the apron. Nearly six weeks passed before serious repairs began; Hill wired Washington that without a new apron before the next flood, they “may lose Granite Reef Dam.” Working two shifts with roughly 250 men and 200 head of stock, crews poured about 7,000 cubic yards of concrete in under four weeks. Davis, by then running the Reclamation Service, wrote that “a great disaster was averted only by a narrow margin.”
- 1954–1966. Once Bartlett and Horseshoe dams on the Verde caught the floods that used to scour the pool, silt became the enemy. SRP built a permanent electric dredge, the Katy Pickerell, christened in June 1954. In the flood of December 30–31, 1965, it capsized; five crew members were rescued by helicopter. It was salvaged, rebuilt and back at work by June 1966. One Phoenix headline called it the “Only Ship in Arizona’s Navy.”
- 1978–1995. Floods in 1978, 1980 (up to 180,000 cfs) and 1993 battered the apron and sluiceways. The 1993 damage took a repair contract of more than $868,000 to put right in 1995 and 1996.
Why it matters
Scottsdale likes to tell its origin story as a chaplain buying land beside a canal in 1888. That’s true as far as it goes. But the canal was only as good as its dam, and for its first twenty years the dam was a pile of timber and rock that the river took apart whenever it flooded. Granite Reef is where the federal government made the arrangement permanent. Every alfalfa field, citrus grove and lawn that has drawn on the Arizona Canal since 1908 traces back to this weir. It has no plaque you can easily reach and no visitor center. It deserves a look anyway.