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San Francisco Peninsula Reservoir Wet Weather Operations

Winter 2024-2025

Update November 25, 2024
Occasional rain is expected in the forecast for this week. SFPUC staff do not expect water levels in Crystal Springs, San Andreas, or Pilarcitos reservoirs to approach spillway height. Staff will continue to monitor the dams and reservoir levels per normal wet weather operations.

Please read below how you can monitor reservoir levels and stream flows, as well as how to sign up for alerts from your local jurisdiction.

Wet Weather Operations

The San Francisco Public Utilities Commission owns and operates the Crystal Springs Reservoir system on the Peninsula, which includes Lower Crystal Springs Dam on San Mateo Creek. This reservoir is a key source of drinking water for the San Francisco Peninsula and not a flood control facility. 

 

Location of water flow gauge at Lower Crystal Springs

Creek and Reservoir Level Information

You may access real-time data on creek and reservoir levels at the USGS Current Conditions for California: Streamflow website

Data on Lower Crystal Springs Dam:

11162750  -  LOWER CRYSTAL SPRINGS RES NR SAN MATEO CA  The reservoir will pass all inflowing rain over the spillway once the gauge elevation reaches 294.6 feet.

Data on flows below Lower Crystal Springs Dam: 

11162753 -  SAN MATEO C BL LO CRYSTAL SP RES NR SAN MATEO CA  

Data on San Andreas Reservoir:

San Andreas Lake a Dam NR Millbrae CA - USGS Water Data for the Nation

IF YOU LIVE ALONG THE SAN MATEO CREEK

Residents who live along the creek or who have previously experienced flooding from the creek should take additional precautions to prepare for wet weather.

Encourage your neighbors to sign up for SMC Alerts https://www.smcalert.info/ and be sure to register with your address

LOCAL JURISDICTION PREPARATIONS

San Mateo Residents: visit www.cityofsanmateo.org/floodprep for information on sandbags and storm safety.

Hillsborough Residents: visit https://www.hillsborough.net/ for up to date information.


 

Mid Coastal Areas of San Mateo County 

Stay up to date at the City of Half Moon Bay Website. 

Pilarcitos

The gauge for Pilarcitos Reservoir is found here:

The rate of discharge from the reservoir, in cubic feet per second, is found here:

 

Location of water gauge on Pilarcitos Creek

Half Moon Bay

The flow of Pilarcitos Creek near Half Moon Bay can be found here (Please note that this gauge is measuring all the runoff collected in the watershed downstream of our reservoir and may vary significantly from the flow at the dam)

Location of Pilarcitos Creek at Half Moon Bay