Wave patterns are as important to surfers as currents are to sailors. Mess with the waves and the thrill is threatened, the surf spoiled, the endless summer eclipsed.

So what is a lost wave worth?

That is the issue for Chevron Oil Corp. and the Surfrider Foundation, an 8-year-old surfer activist group dedicated to protecting the surf.

Chevron changed the wave patterns along a stretch of Southland shore in 1985 when it built a rock groin, a jetty-like projection, 150 yards out into the Santa Monica Bay off El Segundo. The groin was constructed to help protect underground pipes that connect the El Segundo refinery to offshore terminals.

Chevron officials acknowledge that they are responsible for the wave changes in the area just south of Dockweiler State Beach, and have promised to do something about it. But the California Coastal Commission, impatient with Chevron's inaction, has told the company to accept one of three Surfrider suggestions to compensate for the lost waves or come up with some ideas by the end of the month.

Surfrider suggested that Chevron consider building an artificial sandbar out of sandbags, reconstruct the beach profile from time to time to allow the ocean currents to form real sand bars or contribute about $250,000 to a foundation for research into the development of artificial reefs.

"What we want is them to replace the surfing breaks that were lost," said Scott Jenkins, the environmental director for Surfrider and a lecturer and researcher at the Scripps Institute of Oceanography in La Jolla.

Chevron has offered to build a freshwater shower on the beach, but the offer did not impress the Surfrider Foundation, which has 15,000 members nationwide and recently won a $5.8-million lawsuit against two Northern California pulp mills that were polluting the Pacific.

Chevron is trying to "trivialize" the loss of the surf breaks, Jenkins said.

Ron Spackman, Chevron's director of public affairs, said the company will do what is "practical or reasonable" in terms of cost to benefit surfers. However, he said that building sandbars, real or artificial, is too expensive and subject to the whims of Mother Nature, who could easily wipe them out.

Surfrider and Chevron representatives met Wednesday in what is expected to be a series of sessions aimed at devising a solution agreeable to the Coastal Commission.