San Diego County Superior Court Judge Yuri Hofmann ordered the city to comply with a 2005 order by another judge to restore the Children's Pool cove to its original condition in response to a lawsuit filed by a disgruntled swimmer.
The city plans to hire someone to walk the beach with a public address system broadcasting the sound of barking dogs to scare off the seals, said Andrew Jones, the assistant city attorney for civil litigation.
The city cannot use force because the seals are a federally protected marine species.
"There's certainly a lot of emotions revolving around this issue," Jones said. "We expect that this person could be harassed, even physically attacked," he said.
Two police officers will be on hand to prevent interference by pro-seal activists, he said.
The Children's Pool is one of only two beaches in Southern California where harbour seals give birth and nurse their young.
The plan, which was created with the help of the National Oceanic and Atmospheric Administration, would cost an estimated $688,000.
At the same time, attorneys for seal supporters filed an emergency motion with the 9th U.S. Circuit Court of Appeals late Monday hoping to prevent the animals' ouster. They also plan to file papers in state court and hold a rally later this week.
An appeals court decision could come by Wednesday, said Bryan Pease, an attorney for several pro-seal groups.
Seal proponents would also get a boost from the state if Gov. Arnold Schwarzenegger signs a measure passed earlier this month by the state Assembly, giving the city control over the fate of the seals. If it is signed by the governor, the City Council would likely declare it a seal sanctuary.
"The seals need rest each day. If they don't get their rest, their health will be jeopardized and the local community will also suffer a huge economic cost," said Dorota Valli, who coordinates a pro-seal campaign for the Animal Protection and Rescue League. "It's an enormous tourist draw."
At the pool yesterday, about two dozen seals lounged lazily on the sand and paddled about the shallow cove as throngs of tourists watched them.
One wasn't impressed.
"I don't particularly like them. I think they smell, and I'm not interested in looking at them," said Kees (KAYSE') Hendricks, 60, of Vancouver Island in Canada. "I don't think there should be a whole beach for the seals."
But others said they found local residents' complaints about foul odors from the seals to be exaggerated.
"Well, to me, it's the aroma of the sea," said resident Ken Walsh, 58, a nearby resident who swims in the ocean daily.
"There's a lot of places where the seals are not," Walsh said. "And I think we should feel privileged to be in a spot where people want to come just to see those little seals."
Children's Pool was created by a sea wall built in 1931 through a gift by La Jolla philanthropist Ellen Browning Scripps. The state, which owns the cove, subsequently placed the beach in a trust and listed several possible public uses for it, including a children's beach and a park.
Seals began showing up in increasing numbers during the 1990s. In 1997, the city posted a warning that the pool shouldn't be used because it was contaminated with high levels of bacteria from seal waste. Still, some people continue to use it.
The judge's ruling Monday is the latest development in a lawsuit filed in state court in 2004 by a swimmer who grew disgusted with the seal waste and alleged a seal sanctuary did not meet the uses listed in the state trust.
Paul Kennerson, an attorney for the swimmer, did not return a message Monday.
Another federal case was recently dismissed on jurisdictional grounds, Pease said.
It's unclear what steps the city could take if the plan to scare away the seals fails.
"That's a good question," Jones said in a telephone interview. "Do you have any suggestions?"