Several engineers will spend the next few weeks 20 feet underground fixing a crack in a large water pipeline that spans almost the entire length of San Diego County.

The San Diego County Water Authority discovered a leak earlier this month in a portion of its 90-inch Pipeline 4, which has carried water since 1966 from the Skinner Water Treatment Plant near Temecula down to the Otay Reservoir near Chula Vista.

“We have very old, aging infrastructure so we’re always keeping tabs on things to make sure we can stay ahead of any failures or issues with our pipe,” said SDCWA Principal Engineer Brent Fountain.