A century or so ago, flood control and water supply were serious issues in our region and, by the late 1920s, Carbon Canyon was an area of focus for both. Major floods in the mid-teens and incessant growth foreshadowing the need for water from the Colorado River led local agencies to adopt plans, such as a flood control dam on the Orange County side near Olinda and, amazingly, a dam and reservoir to fill the San Bernardino County part of the Canyon from the county line to the summit. The former was not built until 1957, while the latter was seriously considered, but, of course, not pursued.
Formed in 1928, the Metropolitan Water District of Southern California quickly considered two sites for the future Colorado River Aqueduct terminus: the existing Puddingstone Dam and Reservoir in San Dimas, and Carbon Canyon. Many engineers favored the Canyon concept as being less logistically complicated, safer, and more cost-effective. The May 9, 1930 edition of the Champion somewhat light-heartedly laid the matter out: “Carbon Canyon residents south of the summit may find themselves under many feet of water if they continue to live on their present locations and the proposal to construct a high dam at the county line is ultimately approved.”
The paper went on to note that locals reported that engineers and surveyors were roaming the canyon the prior several days “mapping out plans for the construction of a dam which will impound millions of acre feet brought by aqueduct from Banning to Chino to supply” the customers of the MWD. This much higher edifice in lieu of the flood control dam proposed for the Olinda area would be just east of the county line where a “greater reservoir will be provided with the hills at [the] summit end providing the enclosure . . . the dam site is just below the Tidwell store in Sleepy Hollow at the concrete bridge.” This would be where Carbon Canyon Road crosses Carbon Creek at the site of the recently demolished Canyon Market liquor store.
The Champion cautioned that “there need not be any panic about this proposal . . . [as] it would require a considerable length of time before any dams could be started in this neck of the woods.” The article ended with “we just pass the word along so that those who live to fish, swim and boat can dream about what may be in the years to come.”
At the end of 1930, the Champion reported that the Carbon Canyon terminus, with its reservoir four miles long and a mile wide, was recommended by an engineers’ board of review to the MWD’s board of directors. By early the next year, the paper reported that surveys were underway in the Chino Valley for an aqueduct termination at either Puddingstone or Carbon Canyon. While this work was not considered definitive, it was noted that they “are being made at this time for study as to the most logical location of the aqueduct terminal.” The route to the Canyon was from Banning through Perris and then Temescal Canyon to Corona and finally into modern Chino Hills. It was added that a lower dam site in the Orange County portion was rejected “because of the narrow confines and unsuitable ground for anchorage.” What changed was that “because of spreading [grounds] possibilities a much lower [shorter] dam would be necessary and the cost would be considerably lowered.” From a total project cost pegged at about $200 million, $17.5 million was allowed for “purchase of properties in the Canyon, which are now populated to a considerable extent” along with construction-related costs.
In the end, the MWD decided to cut costs and logistical headaches by terminating the aqueduct at today’s Lake Mathews south of Riverside. Feeder lines brought the first supplies to the area in 1941 and a later branch for Orange County was built through Tres Hermanos Ranch to the Diemer treatment plant next to Carbon Canyon Dam. The later discovery of earthquake faults in the Canyon area lead to the obvious question of “what if?”
Editor’s note—So Carbon Canyon has now survived a dam, an airport and a ski resort.