Broken sewage line.

Broken sewage line. (April 12, 2012)

Work began today to repair a regional sewage line that ruptured and spilled thousands of gallons of sewage, possibly into a nearby creek that empties into the Pacific Ocean.

Sewage service was not affected, but Carlsbad, Encinitas and Vista residents were asked to reduce their water usage, according to the Encina Wastewater Authority.

Traffic was blocked today from Avenida Encinas between Palomar Airport Road and Poinsettia Lane, and the stretch of road is expected to remain off-limits to motorists tomorrow.

Water samples collected from the mouth of Encinas Creek confirmed the water is safe for recreational use, but signs warning of a potential contamination will remain posted near the water tomorrow, said Debbie Biggs, director of environmental compliance for the Encina Wastewater Authority.

A 4 1/2-foot-diameter concrete pipe collapsed on the grounds of Encina Wastewater Treatment Plant in Carlsbad on Thursday, causing an overflow that continued for almost 14 hours, the agency said.

Repair workers got the problem under control early Friday morning, when they completed installing temporary bypass lines, Biggs said.

Authorities are unsure how much sewage escaped the system, though the county Department of Environmental Health put the number at roughly 5,000 gallons several hours after the spill began.

Also remaining unclear this afternoon is the question of whether any of the pollution got into nearby Encina Creek, which flows into the ocean less than a quarter-mile away.

``We think we pretty much captured everything in the plant (property),'' Biggs said.

Wastewater authority personnel are working to determine the cause of the failure, the size of the spill and the extent of environmental contamination, if any, she said.