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Using Translation

The County of San Mateo has added a translation feature developed by Google Translate to assist web visitors in understanding information on this website in a variety of foreign languages. Please be aware that Google Translate, a free third party service which the County does not control, provides automated computer translations that may not give you an exact translation. The County cannot guarantee the accuracy of translations through Google Translate so translations should not be considered exact and only used as a rough guide. Anyone relying on information obtained from Google Translate does so at his or her own risk. The County disclaims and will not accept any liability for damages or losses of any kind caused by the use of the Google Translate feature.

  • learning about and mitigating landslides due to climate change


Climate change is expected to increase the frequency of debris flows, or fast-moving landslides or mudslides, on the slopes of San Mateo County as storms and fires become more frequent. As many South Coast and Southern San Mateo County residents learned after the 2021 CZU fires, areas with wildfire burn scars are at higher risk for debris flows during storms. Storms can also increase debris flow risk, especially when soils are already saturated. During the Winter storms of 2022-23, many landslides and debris flows occurred that cut off major roads including Highway 92. These events can occur suddenly, and debris can flow for miles and result in extensive damage.

Areas that have experienced debris flows and landslides in the past may be more likely to experience them again, especially with the increase in extreme precipitation events projected.


Rapidly moving debris and landslides can injure people, disrupt utilities, damage homes and other buildings, and block transportation corridors and transit rails, impacting both commuters and people who need to evacuate. They pose an acute threat to the safety of those who live or who are using roadways below them. The placement of roads in valleys or along the sides of slopes and roads themselves can destabilize slopes over the long term.

Members of socially vulnerable and low-income communities may have fewer resources to recover in the aftermath of debris flows. Renters can have limited control over whether or when their housing may be repaired or rebuilt. Socially vulnerable communities can be more likely to experience challenges during disasters, especially if they also lack access to transportation, lack access to cell phone or internet service, or face language barriers.

La Honda Road mudslide

Possible Adaptation Strategies

  • Develop a communication plan and early warning system.
  • Proactively monitor and assess slopes for slide vulnerability before and after a flood event.
  • Protect homeowners and renters by ensuring that sellers and landlords disclose debris flow and landslide risks.
  • Maintain regulations to limit development in landslide-prone areas.