A crackdown on Venice Beach homeless encampments and renegade vendors is pitting longtime residents and merchants against homeless advocates and younger transients.

The Los Angeles Police Department enforcement efforts, begun almost two months ago, were spurred by mounting complaints from waterfront residents and business owners who said aggressive, intoxicated transients and violent disputes over vendors’ spaces had made the boardwalk an increasingly lawless, frightening place.

Longtime Venetians have expressed delight at having a somewhat sanitized Venice — more “Beach Blanket Bingo,” less “Mad Max.”

PHOTOS: Battle over the Venice boardwalk

“The way it was going, no one was enjoying it, absolutely no one, including the tourists,” said Brad Neal, a landlord on Ocean Front Walk.

But the clampdown has its critics.

The California Coastal Commission has argued that enforcement of a curfew violates state beach access rules. The city of Los Angeles should have sought a coastal development permit before beginning the action, said Deputy Director Jack Ainsworth. The Los Angeles city attorney’s office says it is on firm ground, having determined that Ocean Front Walk was part of Venice Beach park and therefore subject to an overnight park curfew in effect since 1989.

Others say the city runs the risk of taming the wild and woolly atmosphere that has made Venice a destination that attracts 16 million people a year.

“I wouldn’t be surprised if this area became a little Santa Monica, with corporate businesses forcing out the independents,” said Kenneth Karl, 40, a homeless man who occasionally slept at the beach before the curfew enforcement. “You wouldn’t want that. The performers and entertainers are what people come to see.”

Barred from sleeping along the beach overnight, dozens of transients migrated farther inland to an encampment at 3rd and Rose avenues, near Google’s offices. City sanitation crews, under the supervision of LAPD officers, removed the encampment last month, throwing out tents, blankets, cellphones, computers and other personal possessions.

A group of 11 homeless people who lost possessions in that cleanup have filed a claim against the city and successfully barred authorities from seizing their property again.

“People need a place to sleep,” said Carol Sobel, their attorney. “Shutting down where people can be … creates a lot of problems. It doesn’t resolve the issue but just moves them from block to block.”

Venice residents said the mood of the boardwalk area changed drastically about a year and a half ago, with the influx of large numbers of homeless youths, many from the Pacific Northwest. Residents complained that they openly used and dealt drugs on the beach, got into fights, smashed bottles, spat on passers-by and panhandled aggressively.

“It was definitely a rowdier, rougher group than we’ve ever seen,” said Daniel Samakow, a boardwalk restaurateur.

The problem spread to boardwalk vendors. With too many sellers vying for 205 slots along the west side of the boardwalk, police said, some began hiring the young transients to protect their selling spaces. Some of those vendor vigilantes used force, intimidating artists and musicians who stopped showing up. The young “travelers” also used their proceeds to buy medical marijuana from boardwalk clinics and then resell it, said Capt. Jon Peters, commander of the LAPD’s Pacific Division.

“The ability for young transients to make some money became very problematic,” Peters said.

Police documented a 16% rise in aggravated assaults and responded by enforcing a midnight-to-5 a.m. curfew and new rules for boardwalk vendors, passed by the Los Angeles City Council in December. It replaced a previous effort to rein in vending that a court struck down in 2010.

Now, any merchandise with utility beyond protected speech, such as clothing or jewelry, is prohibited on the west side. Peters said the change was meant to eliminate the many vendors who were reselling cheap imports, a practice that angered rent- and tax-paying merchants on the east side.

Police officers say they spent weeks explaining the rules to residents and boardwalk denizens, then began enforcement in mid-February. For the most part, people voluntarily complied, police said.

On patrol one recent night, Sgt. Dan Gonzalez drove a marked police SUV up and down the boardwalk, reminding residents, joggers and transients alike about the curfew. When Gonzalez paused on his rounds, Gary Harris, a 20-year resident who was hustling home to beat the clock, leaned into the patrol vehicle and thanked him.

“You have no idea what a disaster it was until recently,” Harris said. “The new ordinances have changed our lives. We’re just thrilled.”

PHOTOS: Battle over the Venice boardwalk

martha.groves@latimes.com