Horse owners won a skirmish with clean-water advocates when the California Coastal Commission voted Monday against ordering relocation of a horse stable and arena complex near Agoura Hills.

Heal The Bay, the Sierra Club and others had blamed Malibu Valley Farms on Mulholland Highway for adding bacterial and nutrient pollution to a usually dry creek that drains through Malibu Creek into a lagoon and the famous Malibu surfing beach.

But on a 7-5 vote Monday night in San Luis Obispo, the Coastal Commission said the large horse breeding, boarding and exhibition facility could remain in its present configuration if its owner takes some minor additional steps to prevent contaminated runoff.

"Malibu Valley Farms offers a safe zone, a green pasture that provides a shelter for all the horses in the area when there is a fire," testified Calabasas veterinarian Dr. Richard Stevens. "They do outstanding manure management and they control the runoff."

But ocean advocate groups believe the hundreds of horses using Malibu Valley Farms are responsible for bacterial and nutrient pollution measured just downstream from the horse facility, in Malibu Creek State Park, the Malibu Lagoon and at Surfrider Beach.

"The extent of the unpermitted development at this site is widespread and detrimental to water quality, and it likely contributes to degraded water downstream at Heal The Bay's monitoring sites," said Tarren Collins, who was representing that group.

Horse advocates from across the state, including the California Thoroughbred Breeders Association, urged the commission to allow the equestrian center to continue operations with its state-of-the-art vegetated swale to eliminate horse urine and manure from the dry wash.

Several dozen horse owners, riders and fans took a chartered bus to the commission meeting in San Luis Obispo. The fight to save the equestrian center had galvanized horse owners, who are concerned about growing pressures on equine ownership caused by spreading urbanization and environmental concerns.

The decision ends a 15-year enforcement action brought by Coastal Commission staff members against Malibu Valley Farms owner Brian Boudreau.

His victory came two years after losing a fight to build a timeshare resort, winery and restaurant next to the equine facilities. Calabasas voters rejected his request to be annexed and to rezone the resort, in large part because of the project's rural location.

The horse farm sits across Mulholland Highway from the King Gillette Ranch, which was purchased two years ago to serve as the new visitor center and headquarters for the state and federal parks network in the Santa Monica Mountains. Commissioners said Monday that visitors to the park will be aided by having a large horse facility adjacent to it.