Riley Wants Answers on Open-Space Houses Snafu : Regulations: County planning staff members will brief the supervisor on how 21 homes came to be built on public land in the new Robinson Ranch development.

Supervisor Thomas F. Riley wants county planning specialists to explain how a developer was able to build 21 homes on land designated as public open space, an aide said Friday.

“He wants to look at all the information presented,” said Kenneth H. Bruner, Riley’s executive assistant, adding that a briefing has been scheduled for Monday afternoon.

The session is to come on the eve of the Board of Supervisors’ consideration Tuesday of a staff recommendation to relinquish the public’s right to the 3.35 acres upon which the homes are built. The sites are in the Robinson Ranch planned community, next to wide-open ranges of chaparral directly down the slope from Saddleback’s Modjeska and Santiago peaks.

Bruner said Riley, whose district includes Robinson Ranch, is “disinclined at present to announce how he will vote” on relinquishment.

Based on information available to date, Bruner said, he will continue to advise that Riley follow the recommendation of county planning officials. In a summary submitted to the supervisors, the Environmental Management Agency has attributed the construction to inadvertent mistakes by a title company and a private engineering firm.

“It simply is an unclear spot on the title,” Bruner said.

Robert E. Hamilton, the county’s manager of program planning, repeated Friday that the developer, the William Lyon Co., has provided 500 acres of open space for Robinson Ranch, 5% more than required.

Hamilton said the staff’s recommendation to relinquish the 3.35 acres is consistent with a provision, included in a 1985 plan for the area, to accommodate adjustments to the development’s urban and open-space boundaries.

Representatives of the Lyon Co. have said they were unaware of the open-space designation until recently, when it was brought to their attention by Hunsaker Associates, an Irvine-based engineering firm that processed the Robinson Ranch planning documents.

Executives of Chicago Title Insurance Co.--the firm that acquired Ticor Title Insurance, which failed to note the 3.35 acres when planning documents were filed with the county--did not return calls for comment Friday.

Records indicate that the county in 1989 approved the Robinson Ranch development without realizing that it included the 3.35 acres of open space. Had the county known of the open-space designation in 1989, Hamilton said Friday, the supervisors would have relinquished the land and approved construction of the homes there.

“This isn’t a matter of the county losing something it’s entitled to,” Hamilton said.

That position was disputed by Sherry Lee Meddick, chairwoman of the Rural Canyons Residents Assn.

“I think the developer ought to take all the profits from the sales of these homes and use it to buy new open space for the county,” said Meddick, who has criticized county government’s relationship with developers.

Paul M. Christiansen, a Laguna Niguel City Council member who has taken an interest in how the county accounts for its parkland and open space, said: “I’m so sick and tired of hearing, boundary adjustments. If it’s done right in the first place, there should be no need for an adjustment. . . . Land planners call it a boundary adjustment. I think it’s a giveaway of the taxpayers’ land.”

Meanwhile, Robinson Ranch residents who live near the affected acreage appear to be of different minds regarding the discovery of the open-space designation: Some said they are unconcerned; one man, who asked that his name not be used, said the events seem implausible.

“I don’t agree with them saying, ‘Whoops, it’s a mistake,’ ” said the man, a resident of Shadow Rock Lane.

Correspondent Frank Messina contributed to this report.