Chevron USA Inc. has agreed to pay a $1.5 million penalty for discharging excessive pollutants into the Pacific Ocean from its petroleum refinery in El Segundo, Calif., the Justice Department announced yesterday.

"This is the largest civil penalty obtained in the settlement of a Clean Water Act case relating to discharges from a single industrial facility in the last 10 years," acting Assistant Attorney General Roger Marzulla said.

The agreement bars Chevron from any further pollution violation at its plant near Los Angeles.

The company was accused of discharging excessive amounts of phenol, ammonia, oil and suspended solids into the ocean.

In a major civil environmental suit filed in August, the federal Environmental Protection Agency accused Chevron of 880 violations of federal pollutant discharge limits since 1981 at the company's El Segundo oil refinery.

The suit sought $8.8 million in penalties.

Chevron officials had recently conceded that heavy storm water flows contributed to pollutant discharges in excess of federal limits in the past.

But they said construction of $25 million worth of new waste treatment facilities and a new $22 million effluent diversion project virtually halted the problem.

Attorneys for the Sierra Club, which has a similar civil suit pending against Chevron, concede there have been improvements but say there is also some evidence that the company violated a limit on total suspended solid pollutants as recently as Jan. 1.