OneShoreline has been managing, upgrading, and expanding the San Mateo County flood early warning system to support emergency alerts and preparedness. As part of this work, a flood monitoring webpage has been created for direct access by both emergency responders and the general public:
https://oneshorelineearlywarning.onerain.com
The flood early warning system is an integrated network of stream, precipitation, and tide stations located to monitor real-time conditions. This system provides two major functions: an alert system, and data collection to proactively plan and implement stormwater management solutions.
Note that actual flood conditions may vary due to channel conditions or blockages, sensor errors, or other complicating influences. With any significant storm, please stay alert and follow the local forecast, news, and this website. This site contains provisional data from automated sensors; the data are presented without formal review and are provided for informational purposes only. OneShoreline does not assume any legal liability or responsibility or make any guarantees or warranties as to the accuracy, completeness, or suitability of the information for any purpose. The public is urged to closely monitor information provided by local emergency management offices during emergency situations.
If water levels reach established thresholds, alerts are released to key contacts to watch conditions more carefully and to provide warning for when flood impacts may be expected. If a flood notice is warranted, the circles on the map will become orange (watch) or red (warning). Alert thresholds have been established for creeks throughout the county based on historic information and modeling. OneShoreline continues to explore methods for data collection, presentation, and decision-making.
Data collected over time is made available through the public interface.
Fall 2024 installations are planned for a signal repeater at the San Bruno Mountain station to allow for further system expansion and to improve signal strength and reliability, as well as for a new station to be located in Millbrae.
