LOS ANGELES — Los Angeles is restoring a century-old water tunnel to capture runoff from the Sierra Nevada, which had a record snowfall this winter after years of drought.

The Department of Water and Power is spending $4.5 million to repair and reopen a 2-mile-long tunnel that once carried water from the Los Angeles Aqueduct to a now-defunct reservoir, the Los Angeles Daily News reported (http://bit.ly/2tOLfTE).

The tunnel is part of the Maclay Highline system of channels and tunnels that supplied water to homes and farms in Sylmar and the Sunland-Tujunga area. It was dug in 1915, the same year that residents of the San Fernando Valley voted to become part of Los Angeles.

It was retired 30 years ago.

Los Angeles currently relies on Sierra Nevada water to slake its thirst following years of drought when runoff was in short supply. The tunnel restoration aims to capture excess runoff and store it underground for future use.

When it reopens this fall, the tunnel will carry 130 acre-feet of water a day — enough to supply 260 households with water for a year.

It will help carry water from the aqueduct to Pacoima, where it will be released into basins to filter more than 400 feet underground into the city’s aquifer.

“We do have, on the books, a huge groundwater treatment system being constructed,” said Michael Grahek, a DWP operations manager. “This ties into that. We will have groundwater for years to come.”

“It’s part of our ongoing effort to maximize the use of available water for our customers,” he said.