Huntington Beach is taking its rivalry with Santa Cruz over the title of "Surf City, USA" out of the ocean and into the hands of lawyers, trademarking the name and chasing down businesses that infringe on it.

The Southern California town, which boasts a surfing museum and a hall of fame, announced in May that the U.S. Patent and Trademark Office had awarded it exclusive use of the title. Now it is enforcing its rights, sending cease and desist letters to anyone wading into its waters.

One of its first targets, the Santa Cruz beachwear shop Noland's on the Wharf, has been selling bathing suits and beach hats for nearly half a century.

The shop has been warned it has until Friday to stop selling a T-shirt sporting the words "Santa Cruz" and "Surf City." Sales of the shirt have since skyrocketed, selling out and leading to a waiting list with nearly 300 names.

Business has been so brisk that Ginger Noland, who runs the shop and two others with her son, Bruce, had to take on an extra employee to help.

"The big waves are here, but they have the deep pockets," Noland said.

The Huntington Beach Conference and Visitors Bureau spearheaded the move to trademark the moniker, and has developed a marketing effort that includes a logo and franchise deals to put the image on beach cruisers, furniture and even a "Surf City" credit card.

"Our brand is taking off because the Surf City USA image we put there is authentic and real, not some contrived image we concocted out of thin air," Doug Traub, the visitors bureau president, said in a statement posted on its Web site. Neither bureau representatives nor their attorneys were available for comment.

The dispute between the cities began years ago.

With both cities featuring a burgeoning surf industry and hosting dozens of contests, there have been a number of face-offs, from good-natured challenges to a surf competition, with the winner taking the name, to proclamations from legislators representing the two areas.

But the latest twist seems to put a definitive end to the back-and-forth.

"We are the real Surf City," Noland said. "It's just that legally, we can't do anything."

Until Friday's deadline, Noland said she's ready to take her sport utility vehicle and drive to Paso Robles, where the T-shirts are made, to restock the store and sell as many as possible.