Dam Safety Program

MMWD manages seven reservoirs to capture and store 75% of the water we supply to customers. Our reservoirs include Phoenix, Lagunitas, Bon Tempe, Alpine and Kent on Mt. Tamalpais, and Nicasio and Soulajule in west Marin. Together they hold 79,566 acre-feet of water, or about 30 billion gallons.

MMWD has a comprehensive Dam Safety Program to ensure all of our dams and spillways are safe and functioning properly. This program includes three main components: monitoring, routine inspections and maintenance, and emergency preparedness and response planning. The district also works closely with state and federal regulators and local emergency response partners to ensure public safety.

Monitoring


MMWD continuously monitors conditions at the dams and spillways to ensure they are functioning as intended. Instruments placed on and in the dams track and record parameters such as water seepage, dam movement and water pressure. 

MMWD engineering technicians also perform monthly visual inspections of each dam. In addition, MMWD rangers tour the dams frequently—often daily during rainstorms—and live onsite at Phoenix, Alpine and Soulajule dams. Other routine visits are made by maintenance and water quality lab personnel.

Inspections and Maintenance


Through ongoing maintenance, we are able to protect the dams from deterioration and prolong their lifespans. MMWD routinely inspects the condition of each dam and spillway and provides an annual instrumentation report to the Division of Safety of Dams (DSOD) under the California Department of Water Resources. In addition, each year MMWD jointly inspects each dam with DSOD. 

The most recent field visit by DSOD was February 7-8, 2017. 
The latest DSOD reports include a review of the district-submitted instrumentation report and confirm that all of MMWD’s dams and spillways are safe and in good condition. 
 

Emergency Preparedness and Response


At the core of our Dam Safety Program emergency response and preparedness is our post-earthquake dam evaluation team. After significant earthquakes, trained personnel inspect the dams for any signs of damage, and the dams’ monuments are surveyed by the district surveyor to check for any vertical or horizontal movement. 

In addition, MMWD works with other agencies and public safety personnel on emergency action planning and training exercises. Our Operations Center is staffed 24/7 year-round, so we are able to activate our Emergency Operations Center (EOC) at any time to coordinate the actions of MMWD first responders. 

Division of Safety of Dams Inspection Reports



2017 

2016 

Alpine


Bon Tempe


 Kent 


 Lagunitas


 Nicasio 


Phoenix


 Soulajule


Soulajule Spillway