Water main break in San Mateo shuts down roads, forces school closure

A large water main break in San Mateo caused flooding caused flooding in a neighborhood near Central Park at South El Camino and Notre Dame Ave. on February 8, 2018. A large water main break in San Mateo caused flooding caused flooding in a neighborhood near Central Park at South El Camino and Notre Dame Ave. on February 8, 2018. Photo: KTVU Photo: KTVU Image 1 of / 3 Caption Close Water main break in San Mateo shuts down roads, forces school closure 1 / 3 Back to Gallery

A water main break on Thursday temporarily closed two lanes of a major San Mateo thoroughfare, police said.

The break occurred around Notre Dame Avenue and South El Camino Real, closing two lanes on the latter road near Ninth Avenue, according to a statement from San Mateo Police Department. The road was reopened at 12:30 p.m., but officials said to expect residual traffic delays.

California Department of water officials responded to the scene about 7 a.m.

Investigators remain on site as they try to determine the cause of the break. Police said a 24-inch water transmission line busted at the intersection of El Camnio Real and Notre Dame Avenue, which caused the flooding.

The pipe is owned and managed by CalWater, which shut off the water line. The agency said that water quality and water service has not been affected by the shutoff.

It has affected water pressure in Hayward Park and Central San Mateo, police said.

The break flooded nearby areas and prompted St. Matthew Catholic Church and Aragon High School to close.

Jenna Lyons is a San Francisco Chronicle staff writer. Email: jlyons@sfchronicle.com Twitter: @JennaJourno