In 1863, prospectors led by Joseph Walker and Pauline Weaver, discovered placer gold along the upper Hassayampa River, northeast of Wickenburg, and not too far north of Wickenburg, where a surface nuggets covered the ground on what came to be called Rich Hill. Gold fever resulted in a large influx of prospectors hoping to strike it rich. However the lack of water needed to placer mine brought disappointment and frustration. The Hassayampa has yearly cycles of a lot of water and no water in the summer. It was said that there was either enough water to float a steamboat or dry enough that the fish had to carry canteens.
The approximate location of the Walnut Grove Dam, which failed in 1890.
Work on the Walnut Grove dam began in 1886 and was completed in late 1887. It was to serve two purposes: to provide the water need for placer mining and to irrigate over 500 acres of farmland below the dam.
The Walnut Grove dam was a loose rock dam. It consisted of a mass of loose rock placed together with some degree of care. When properly constructed it should be as substantial as one made of masonry. Its destruction was not a result of poor design, but of carelessness in some of the details of its construction. They did not take enough care when placing the loose rocks together. Smaller stones should have been used to fill the interstices between the larger ones so that settlement could be the least possible. An emergency spillway of adequate proportions is very necessary. This would be used to release water to keep water from flowing over the top of the dam when the reservoir received a substantial increase in water. Water flowing over the top of the dam would result in the dam settling and if this would happen, the dam would fail. The original plans called for a spillway 55 feet wide and 12 feet deep. As a cost saving measure, the spillway completed was 15 feet wide and 8 feet deep.
On February 18, 1890 there was strong precipitation in the Bradshaw Mountains that persisted for three days. The warm rain on top of the larger than normal snow pack, resulted in a huge runoff. On the third day the water behind the dam was rising at the rate of 18 inches per hour. The amount of water entering the lake behind the dam was so large that the too small spillway discharge was not sufficient to keep the level of the lake from rising. Moreover, the spillway was soon blocked with trees and rubbish. Attempts to free the spillway with dynamite were not successful. Soon water began flowing over the top of the dam and it was clear that disaster was eminent.
When the Superintendent of the dam realized that the dam could not be saved, he initiated a last minute emergency plan. He turned to Dan Burke, who had been hired as the company’s blacksmith, and he asked Dan to ride down the Hassayampa and warn people of the imminent disaster. Since Dan was a long time resident of the area and knew the area well he seemed like the right choice for this mission. Dan was to ride 4 miles downstream to the diversionary dam that was under construction, to warn the workers of the imminent disaster. Unfortunately Dan had a real fondness for alcohol and he only got as far as Brow’s Saloon, where he got so drunk that he never carried out his assignment.
When the dam failed at 2:00 AM on February 21, 1890, it released one of the largest volumes of water ever released from a dam failure in the United States. When the water rushed down the steep and narrow Box Canyon it was 80 feet tall. Fish were found in canyon walls 80 feet above the Hassayampa. When it reached Wickenburg, a distance of 30 miles, in two hours, the wall of water was 40 feet tall.
There were between 70 and 100 deaths. It appears that either all, or nearly all, of the fatalities occurred upstream from Wickenburg. The dam was never rebuilt.
The town of Wickenburg, originally called Pumpkin Patch, is located on the Hassayampa River flood plain. It was originally called Pumpkin Patch because the Indians used it extensively for the growing of crops. This flood plain provided fertile soil for farming and ranching. After Henry Wickenburg divested himself of the Vulture Mine, he planted a large orchard on this flood plain. His orchard was destroyed in the flood. One of the biggest losses Wickenburg suffered because of the flood was the tremendous amount of fertile soil that was washed away.
Several lawsuits were filed against the owners of the dam, but not a single dime was ever collected. One of the suits filed was by Henry Wickenburg. Henry was financially ruined by the Walnut Grove dam disaster. He committed suicide on May 14, 1905, an old and broken man.