Water Levels and Flood Control

The lagoon water level is regulated on a seasonal basis to optimize flood control, recreation, aesthetics, and ecological benefits. During the winter the water level is lowered to provide a receiving basin for stormwater runoff as protection from lowland flooding. The summer water level provides optimal conditions for swimming, boating, and other recreational uses. The water level is controlled using the O’Neill Slough intake gates on the lagoon's south end and the Marina Lagoon Pump Station on the north end. The pump station's pumping capability, in combination with the winter operating level of 95.0 to 95.5 feet, provides the capacity for a 100-year storm event. Click here to view the Marina Lagoon Level and Pump Status Dashboard.

In the spring of 2019, San Mateo Public Works performed routine maintenance on the pump station and re-installed it ensuring its longevity. You can watch this video of the pump station being re-installed.

Marina Lagoon Operating Levels

*Elevation reference is the San Mateo datum +100.
Period	Level Adjustment	Operating Range (ft)*	Comments
May 1 – October 31	-----	96.4 - 96.9	Summer operating level
November 1- November 30	-1 ft. to -1.5 ft.	95.4 - 95.9	Preparing for winter rains
December 1 - April 14	-0.4 ft. to -0.9 ft.	95.0 - 95.5	Winter operating level
April 15 - April 30	+0.4 ft. to +0.9 ft.	95.4 - 95.9	Spring intermediate level
May 1 - October 31	+1.0 ft. to +1.5 ft.	96.4 - 96.9	Summer operating level

Please note that in the event that the dates above fall on a non-working day, implementation of new operating levels may take place on the next working day.

No dock maintenance period is currently proposed for the 2025/26 rainy season. The City is currently evaluating alternatives to lower the operating level below 95 ft. For more information, please refer to the "Marina Lagoon Pump Station - Lower Below Elevation 95 Alternative Analysis Memorandum 2024", prepared by Schaaf & Wheeler and linked below on this page.

The pumps at the Marina Lagoon Station are set to start and stop based on the water level in the lagoon. Residents can read the water level elevation through the gauge outside of the pump station. The settings for the pump start/stop elevations are shown below. With storage in the lagoon (from 95’ to 97.3’) and five pumps in service, the system has the capacity to handle the 100 year storm event.