Is Crystal Springs Dam construction work near end?
If it seems as though completion of improvements and renovation work on the Crystal Springs Dam is taking forever, well, you can be forgiven for your pessimistic assumption. The upgrades, in all of their various phases, have been going on for at least seven years.
But the finish line may be in sight. The latest estimate for wrapping up construction on the concrete dam west of San Mateo and Hillsborough is “winter 2017.” Presumably, that means sometime late this year. Let’s hope that this target, like so many others, is not overly sanguine.
Built in the late 1880s on the San Mateo Creek (which originates in the coastal hills to the west), the dam is 140 feet in height and 600 feet long. It is a critical part of the massive Hetch Hetchy water delivery system owned and operated by the San Francisco Public Utilities Commission.
At capacity, the lake behind the dam, the Lower Crystal Springs Reservoir, can hold nearly 60,000 acre feet of water.
By comparison, the huge Oroville Dam, much in the news right now, is 770- feet-tall and 6,920 feet across. It can accommodate 3.5 million acre feet of water.
The Crystal Springs Dam is situated on the San Andreas Fault, but it has survived both the 1906 and 1989 earthquakes without even a hint of serious damage.
The current construction effort involves a variety of improvements, including raising the parapet wall at the top by nine feet, strengthening and doubling the width of the spillway, addressing PG&E power updates and building a new, 626-foot-long bridge over the dam (the original bridge, part of Skyline Boulevard, or Highway 35, was opened to the public in 1924).
Water released by the dam continues to feed San Mateo Creek. That waterway meanders east toward San Francisco Bay and runs beneath downtown San Mateo for a time.
Lately, the creek, fueled by winter storms, has been foaming relatively high and fast, depending on the weather and the bay’s tidal action, not to mention the dam’s occasional releases from the Lower Crystal Springs Reservoir.
It is not unusual to experience some winter flooding along the creek’s route. If you are curious, you can visit Arroyo Court (at the historic 1776 De Anza Expedition site) one block north of San Mateo’s Main Library off Third Avenue to view the creek up close and personal during particularly wet and wild weather.
There, you can get an idea of its power and scope. Ultra-pricey homes just across the creek are perched right on its banks. Needless to say, flood insurance probably would make prudent sense in that attractive but low-lying neighborhood.
Frank’s Tannery
Beginning on Tuesday of this week, the San Mateo County History Museum in downtown Redwood City is debuting a presentation of paintings depicting an aspect of an era of heavy industry that almost certainly could not be repeated in this area now.
The art work, to be displayed through May 11, involves Frank’s Tannery, an enterprise that employed hundreds of people and produced 13 tons of leather per week at the height of its existence. The tannery operated from 1872 to 1959.
It also generated significant amounts of polluting materials, including tannic acid, a key ingredient in the tanning process, that eventually wound up in San Francisco Bay.
The vacant tannery burned down in 1968. As you might imagine, not everyone in the area mourned its passing. Now, if you even mentioned the notion of, perhaps, opening a tannery anywhere along the Peninsula, you would be branded an enviro heretic and burned at the stake, figuratively of course. John Horgan’s column appears weekly. You can contact him by email at johnhorganmedia@gmail.com.or by regular mail at P.O. Box 117083, Burlingame, CA 94011.