The county could end up paying millions of dollars to residents after a judge ruled Monday that four projects built by the county diverted high water flows from the Ventura River that slammed onto the bottom of the Monte Vista bluff, causing erosion and damaging houses.

Ventura County Superior Court Judge Glen Reiser also found the co-defendant, the Ventura County Watershed Protection District, liable in a lawsuit involving inverse condemnation, which is when the government builds a public project that adversely affects private property and its value.

The lawsuit, triggered after a January 2005 storm, was filed by 28 plaintiffs who reside in 13 houses on the bluff in Oak View.

Plaintiffs' attorneys Mark Papay and Richard L. Moomau, both of Oxnard, estimated that it will cost the county about $7 million alone to make the bluff stable with a massive concrete wall and protect it from further damage.

"The river has been moved between 400 and 1,000 feet. So we're talking of a distance between three football fields because of the projects," Papay said after the judge's decision. "The long and short of it is that it's pushing the river towards the west. We had a river that in 1904 was a thousand feet away from the bluff, and if nature was left to its course, it would have continued to keep going further away. However, these changes have made it go unnaturally toward the bluff."

Monte Vista was approved for construction in 1956.

Reiser made findings on four projects that were built from 1974 to 2000: the Santa Ana Boulevard bridge, the riprap/levee that protected Live Oaks Acres, a riverside dike and the 2000 Live Oak Creek diversion project.

One of the defendants' lawyers, Thomas Hurrell of Los Angeles, said he was disappointed with the judge's decision.

"We know we put on a good case with some very qualified experts," he said. "In the end, it's the judge that makes the decision. That's about all I can say."

Reiser had issued a tentative decision last week, and it was made final on Monday after a hearing.

Watershed District Director Jeff Pratt said the judge's ruling has "very serious implications" for the district, and for anyone who is protecting property from erosion or flooding.

"If this is the final outcome, why don't we just pack up our bags and leave, because we can't protect property," he said. "Our position is, we protected people from flooding, and we did not impact this bank. These people claimed that our projects affected their property, and our experts said, not a chance.'"

The lawsuit is being decided in two parts.

Judge Reiser heard the inverse condemnation case, and it is possible, if the case is not settled, that a jury will hear two other separate legal issues attached to the lawsuit — that the project is a public nuisance and that it is dangerous.

The plaintiffs' lawyers estimate that the total cost for all the damages, if they are successful on all the legal issues they have raised including inverse condemnation, could be as high as $15.5 million.

This includes attorneys' fees, court costs and compensation for emotional distress to residents. Some have been diagnosed with post-traumatic stress disorder, Papay said.

"Portions of people's backyards have fallen in the river," said Papay, adding that the county put an easement across some properties to stop anybody from putting weight on the back of the properties.

One plaintiff goes out and watches the river all night to make sure it's not going to flood his property, said Papay.

An earthquake, even one outside the immediate area, could trigger a "substantial and dramatic land-sliding affection" on the bluff, Papay said, "to the point where portions of homes could begin to fall in the river."

— Staff writer Tony Biasotti contributed to this report.