San Mateo Creek Winter Storm

Sign up for SMC Alerts and be sure to register with your address.

Visit SFPUC’s web page at for more information, to track reservoir levels and updates.

Updated 10 a.m. 2/2/23

The SFPUC does not believe there will be a reservoir spill at this time. However, future major storms could pose risks and residents along the creek should continue to take precautions - especially if your property has flooded in the past. 

San Mateo Creek & Impacts from the Storm

Local agencies are working closely with the San Francisco Public Utilities Commission on monitoring the impacts of storms on the San Mateo Creek. During times of lower rainfall, residents along the creek may notice increased flow as the SFPUC conducts controlled releases of the Crystal Springs Reservoir to prepare for future rain. 

The SFPUC 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. As part of SFPUC’s prudent reservoir operations, operators may need to conduct controlled releases of water out of Lower Crystal Springs Dam into San Mateo Creek to create space for expected rain inflow. These releases are planned with consideration of current rain and high tides to minimize impacts to San Mateo Creek. The goal of these releases is to reduce the potential for reservoir spillover during periods of extreme storms. If a spill occurs, it would be uncontrolled. 

At this time, water levels in Crystal Springs Reservoir are not expected to reach the dam spillway. SFPUC plans to provide 24 hours notice if a spill were to occur - make sure to sign up for SMC Alerts so we can contact you if this occurs. 

If You Live Along the Creek

Residents who live along the creek or who have experienced flooding from the creek should take additional precautions to prepare for potential impacts from future storms.

Encourage your neighbors to sign up for SMC Alerts ***be sure to register with your address***

City/Town Preparations

The County, City of San Mateo, and Town of Hillsborough continue to work with emergency management officials and the SFPUC to prepare for additional rain in the coming days. The City of San Mateo and Town of Hillsborough manage the integrity of the public sections of the creek, such as through clearing debris and vegetation from within the creek. However, the cities do not control the amount of water that enters the creek from either the reservoir or natural runoff/rainfall. City crews have been removing fallen trees and debris from the waterways during this storm and are continuing to clear areas to minimize blockages. Residents are responsible for debris management on their own private properties. If you have a public area to report, please contact your city’s Public Works Department.

San Mateo Residents: visit for information on sandbags and storm safety.

Hillsborough Residents: visit for information on sandbags and storm safety.