Seal Cove Critical Geotechnical Hazards Area Resident Updates
April 28, 2025 Update
April 28, 2025 Seal Cove Critical Geotechnical Hazards Area Resident Update
MWSD Board Action on May 1st
On May 1st, the MWSD Board will consider continuing this District Emergency as declared at our March 27th Board meeting. A District Emergency allows for faster contracting and response to the emerging issues in the Seal Cove area. This emergency also authorizes the District to seek state and federal financial assistance.
We continue our investigations to recommend safe solutions for Seal Cove water and sewer infrastructure.
MWSD is committed to providing continued updates directly to our Seal Cove customers, and during MWSD Board Meetings.
What is the latest MWSD activity in Seal Cove?
Staff have continued active response in the Seal Cove area. This includes responding to and repairing additional leaks of water and sewer infrastructure, as well as continuing evaluation of safe solutions to maintain water and sewer services. Some key updates:
- Everyone remains connected and served by both water and sewer systems.
- On San Lucas Avenue, we have abandoned both our water and sewer mains west of the Del Mar Avenue intersection. We are no longer utilizing these pipes for any water or sewage flows.
- The water main in San Lucas was reconfigured east of the Del Mar intersection. The main now crosses San Lucas, keeps the fire hydrant at the intersection operational, and connects into the water main in Del Mar Avenue.
- We have continued to meet and coordinate with both Coastside Fire Protection District and San Mateo County as we assess our infrastructure in the affected area.
- Our crews have seen increased land movement most recently on La Grande Avenue.
- Water and sewer mains on the western ends of Madrone, La Grande and Los Banos Avenues, as well as the Park Street and Beach Street intersection, are being examined for safer configurations. This may include above ground pipelines, and relocation of water meters for private properties. Above ground pipelines provide increased flexibility and quick visual access, ensuring leaks are less frequent and caught quickly.
Please Remember:
- Check and properly maintain your sewer lateral, shared sewer laterals, sewer sump and grinder pumps.
- Leaks on your private water and sewer laterals may be repaired by a qualified plumber.
- Sewer pump repairs should be completed by the service company (Signa Mechanical) listed on the electrical panels of the pumps.
History of Seal Cove Land Movement
Since the 1960’s there have been numerous, geotechnical studies of the Seal Cove area by San Mateo County, the land use authority for this area.
Study started in the 1960’s, when the U.S. Geological Survey slowed Seal Cove development due to active landsliding and accelerated coastal erosion. In 1971 and 1984 San Mateo County studies confirmed continued instability and geologic hazards. Structural damage due to landslide activity has been documented throughout this time.
San Mateo County
San Mateo County’s Planning and Building Department establishes land use policies and development regulations that protect public health and safety. This includes oversight of County streets and structures on private property.
Emergency Contact Numbers
Water Emergencies: Call MWSD at (650) 728-3545
Sewer Emergencies: Call SAM at (650) 726-0124
Dial 911 for life-threatening and safety
March 31, 2025 Update
March 31, 2025 Seal Cove Critical Geotechnical Hazards Area Resident Update
What Has MWSD Seen Occurring in Seal Cove?
Starting in mid-February, land movement in Seal Cove caused a series of leaks on water and sewer services, and our water mains. This new movement occurred on San Lucas Avenue west of Del Mar Avenue, and Ocean Boulevard between San Lucas and Madrone, in an area of known coastal bluff landslide activity. The Park Street and Beach Street intersection was also affected.
MWSD staff – who are on call 24 hours a day to repair leaks – took quick action to fix these leaks, and also relocate a water connection for 1 home, and provide above ground connections for 2 homes on San Lucas. Above ground connections are a safer means to provide water when land movement can continue to cause leaks. Staff are working to further protect our water and sewer infrastructure in this geologic hazard area, to reduce the potential for any future water or sewage leaks.
- Please check and properly maintain your sewer lateral, sewer sump and grinder pumps.
- All existing Seal Cove customers are connected for both water and sewer services.
- MWSD is committed to providing continued updates to our Seal Cove customers, and during MWSD Board Meetings.
MWSD Board Action on March 27
On March 27th, the MWSD Board took several actions to support fast response in the Seal Cove area:
- Declare a District Emergency, which allows for faster contracting and response to emerging issues in the Seal Cove area
- Authorized specialized investigations to assess and recommend safe solutions for Seal Cove water and sewer infrastructure;
- Temporarily suspend issuing new service permits in the Seal Cove Area for 60 days;
- Authorize seeking state and federal financial assistance;
- Submit a letter to the County of San Mateo requesting collaboration and assistance; and requesting the County proclaim a local emergency, and thus help secure additional financial assistance, if available.
These actions are the standard means for a public agency to rapidly respond to emergencies.
MWSD and San Mateo County
MWSD works with San Mateo County in various ways as we operate and maintain MWSD’s water and sewer systems. San Mateo County’s Planning and Building Department establishes land use policies and development regulations that protect public health and safety. This includes oversight of County streets and structures on private property. The County maintains the public streets and rights of way where MWSD infrastructure is located. MWSD must receive an encroachment permit from the County for any work in public streets. MWSD continues to work with the County to address MWSD assets in closed streets in the Seal Cove area. During this emergency, MWSD is working with the County to identify any grant opportunities that could fund MWSD emergency work, and funding opportunities the County can access to support impacted residents.
History of Land Movement
Since the 1960’s there have been numerous, geotechnical studies of the Seal Cove area by San Mateo County, the land use authority for this area.
Study started in the 1960’s, when the U.S. Geological Survey slowed Seal Cove development due to active landsliding and accelerated coastal erosion. In 1971 and 1984 San Mateo County studies confirmed continued instability and geologic hazards. Structural damage due to landslide activity has been documented throughout this time.
MWSD is reviewing existing County geotechnical reports to determine a plan to safeguard MWSD water and sewer infrastructure.