Marin County is cracking down on several Stinson Beach homeowners who erect makeshift fences in front of their multimillion-dollar homes in summer months, when high visitation can mean unwelcome guests. Beachfront homeowners say the barriers have long been put up to protect against trespassing, but according to county code enforcement officers, the fences are illegal—even those that lie entirely on private property. An anonymous complaint filed on Aug. 13 with Marin County’s Community Development Agency identified five properties— 25 Calle Del Resaca, 28 Calle Del Onda, 28 Calle Del Pinos, 23 Calle Del Pinos and 32 Calle Del Pradero—that had unauthorized barriers made from rope and wooden posts or metal stakes. A subsequent complaint filed a week later flagged a sixth property at 30 Calle Del Sierra, which also had a rope barrier. After inspecting the properties, the agency’s code enforcement division verified the violations, said Gil Sanchez, a supervising code compliance specialist. “We’ve already issued notices of violation, and the next step is for the homeowners to either remove the fence or apply for a coastal development permit,” he said, adding that there is little precedent for such applications being approved. Three of the fences are on private property, while the remaining three are believed to straddle private and public land. But Mr. Sanchez said all the fences were installed without proper permits. Failure to promptly remove or legalize the fencing could lead to escalating enforcement actions, starting with an initial $500 fine if a property owner fails to meet the county’s deadline of Sept. 26. For homeowners who choose to seek a coastal development permit for the barriers, that process comes with a steep financial cost—nearly $9,000 in fees, including a $5,978 planning fee, a $1,449 public works fee, an $857 environmental health services fee, and a 10 percent surcharge, as detailed on the county’s website. “All of this for a minimal rope barrier?” asked one homeowner on Calle Del Pinos who did not want to be named. She said that a rope fence had been present on her property since she purchased it in 2004 and had been put up each summer by the two previous owners going back decades. She defended the barrier as necessary to prevent encroachment by beachgoers, recounting incidents of people barbecuing beneath her deck, hanging towels from her railing and even defecating under her house. All beaches in California are open to the public and regulated by the California Coastal Commission, but tension between private property rights and public access has long simmered on the state’s 840-mile coastline. In 1972, California voters established the coastal commission to safeguard the shoreline, and in 1976, lawmakers enacted the Coastal Act, which declares that all beaches below the mean high-tide line belong to the public. The law mandates that public access be maximized in balance with the “constitutionally protected rights of private property owners.” But according to the complaint filed with Marin County over the Stinson Beach fences, “It just doesn’t seem right that one person, or several in this case, can take beach away from the thousands of people who come out to enjoy the beach each weekend.”