Historic Unfailing Dam Ready for Next 130 Years

                                          Lower Crystal Springs Dam after the 1906 Quake

It was built to last. The 1888 Lower Crystal Springs Dam, situated next to the San Andreas Fault,  survived two major earthquakes—the great earthquake of 1906 and the Loma Prieta in 1989—with no damage.  A critical recent upgrade plus our vigilant 24/7 operation ensure that the historic 175-foot-high dam is able to safely contain Crystal Springs Reservoir drinking water even in a year of record rainfall.

The main upgrade under the Water System Improvement Program was the widening of the spillway—an emergency device for the safe release of water during heavy rains—on top of the dam. The new expanse gives us the ability to release 2.5 times more water than before—if necessary. But again, a spillway is an emergency feature---and one that we haven’t had to use for decades, according to SFPUC Local-Regional Water System Manager David Briggs. 

The real safeguard is the day-to-day monitoring, anticipating and adjusting by our system operators.  They open valves to release controlled amounts of water into San Mateo Creek, and divert water northward to San Andreas Reservoir (at left), on to the Harry Tracy Water Treatment Plant (below), and then to customers. They continually forecast the anticipated amount of rain and runoff into the reservoir and assess that inflow’s impacts on reservoir level.  As needed, our operators will  release controlled amounts of water from the dam—but always taking into account the timing of high tides coming up the creek from the bay.   

We’ve been releasing water from the reservoir this way all winter, and have not come close to spilling water over the dam. 

The San Mateo Daily Journal talked with Briggs a couple of weeks ago.  You can read more on what he had to say about the safety of historic Crystal Springs Dam and our regulation of the water system here. 

Life on the Watershed: Searching for Signs of the Secretive Dusky-footed Woodrat

It’s a small nighttime animal that's critical to the health of the oak woodland ecosystem.  For the most part, it keeps hidden from human view, but the indicators of its presence are there for us to see, especially at this time of year. 

Named for their soot-colored webbed feet, Dusky-footed woodrats are small, secretive nighttime animals that we almost never see. But here in the oak woodlands, the proof of their presence is in their large visible dwellings, called middens. These are sprawling, untidy-looking heaps of twigs and other forest debris nestled into dense woodland growth near the base of a tree--or up a tree between branching limbs.   

Despite the ramshackle look, the midden is durable and water-tight. Its clean interior is neatly organized into a central nest area surrounded by other chambers for storage of different plant, fungus and nut foods, plus numerous tunnels, latrines, entrances and exits.    

The Dusky-footed woodrat is listed as a California species of special concern—meaning a native species now at risk for population and habitat decline—but it is key to our oak woodland ecosystem. It’s a principal food source for larger neighbors, especially certain owl species, as well as hawks, bobcats, and coyotes. Also, after a woodrat dies or moves on, the empty midden soon serves as handy protective lodging for other small woodland dwellers, such as mice, lizards, newts and various spiders and insects.

 

Middens can be hard to see because many are well camouflaged within the trees. But now is a good time of year to spot them, when winter conditions have thinned out some of the surrounding vegetation. 

Look in the wooded areas on either side of the Sawyer Camp Trail. 

Bay Area Pros Check Out Expanded Capacity of Peninsula's Upgraded Water Treatment Plant

Engineers at the Harry Tracy Water Treatment Plant in San Bruno hosted about 50 peers from other water and wastewater facilities throughout the Bay Area earlier this week.

It was an opportune time to show off the plant’s new state-of-the-art features—which now allow for a much increased treatment capacity for up to 60 days in the event of a major earthquake. Though we’re not presently addressing a natural disaster, our Mountain Tunnel in the Sierra Nevada is shut down for two months of inspection and maintenance.  The  tunnel is a major link in that section of the Hetch Hetchy Water System. So during its shutdown all water supply for San Francisco and parts of the Peninsula comes from our local Peninsula reservoirs and through Harry Tracy. The plant is currently treating 80 to 85 million gallons of Peninsula water per day—more than double its usual daily load of 35 million gallons.

And it can do more. Harry Tracy is now capable of treating up to 140 million gallons per day for 60 days within 24 hours of a major earthquake.  The plant upgrade was an essential project on the Peninsula and part of our $4.8 billion Water System Improvement Program to repair, replace and seismically upgrade the entire Hetch Hechy Regional Water System.   

Sawyer Camp Trail Update: Northern Section Closed Again

The San Mateo County Parks Department has closed the northern half of the trail again, from the Hillcrest entrance to the Jepson Laurel, until further notice because of further damage from the weekend rains. 

The northern entrance to the San Andreas Trail, at San Bruno Avenue, is also blocked by a fallen tree. 

For continuing updates, please visit the Parks Department website here.    

Wishing You a Wonderful President's Day

There will be no construction work on our projects through Monday, February 20th. Work will resume on Tuesday, February 21st.

Sawyer Camp Trail Update: San Mateo County Parks Department rangers reopened the northern half of the trail this afternoon, February 17th. The entire trail is now open, dawn to dusk. For questions over the three-day weekend, please call the Ranger Station at 650-573-2592. 

Southern Half of Sawyer Camp Trail Reopened

The San Mateo County Parks Department has reopened the Sawyer Camp Trail from the South Gate to the Jepson Laurel. The section between the North Gate and the Jepson Laurel remains closed until further notice. 

Park rangers have cleared away approximately 10 tons of material from the trail surface and built berms to keep water and gravel from flowing down the trail. 

For updates, please visit the Parks Department website here.

Storms Close Sawyer Camp Trail until Further Notice

The San Mateo County Parks Department has temporarily closed the entire Sawyer Camp Trail until further notice because of flooding, other storm damage, and the possibility of falling trees and landslides.

For updates and further information, visit the San Mateo County Parks Department website here.