Suit Filed Over Freeway Interchange : Leonis Adobe: The impact reports haven’t been done on work planned near the historic home, the action charges.

Three San Fernando Valley homeowner groups have joined a cultural preservation association in filing a lawsuit against Caltrans, saying the agency has failed to prepare legally required environmental impact reports for a planned Ventura Freeway interchange that could affect the historic Leonis Adobe in Calabasas.

Leaders of the Las Virgenes Homeowners Federation, the Calabasas Park Homeowners Assn. and the Woodland Hills Homeowners Organization on Tuesday announced their alliance with the nonprofit Leonis Adobe Assn. at the 144-year-old structure. The Adobe is located in the Old Town Calabasas section, a two-block collection of clapboard storefronts that sprang up around the adobe about 75 years ago.

“Our federation feels strong about the value of an EIR,� said Betty Noling of the Las Virgenes group. “This area is seen as the heart of Calabasas. People identify with it. New residents have a real emotional tie to the area.�

The representatives said the proposed $40-million project, which would replace the heavily used Valley Circle Boulevard bridge over the Ventura Freeway with an interchange, would bring more traffic and development into Old Town Calabasas and destroy the quaint ambience of the community. They said the results would threaten the Leonis Adobe, which is a museum and Los Angeles’ official Historic Cultural Monument No. 1.

The state wants to build an unusual freeway “flyover bridge� as part of the new interchange. The bridge would connect two-lane Calabasas Road on the south side of the freeway with four-lane Ventura Boulevard on the north in Woodland Hills.

“If this flyover is allowed to happen, the devastation of the Old Town feeling will occur,� said Myra Turek, president of the Calabasas Park organization. “There are very few places like this left. The historic value is one thing. The aesthetic value is another.�

Caltrans officials have maintained that the project would not threaten the Leonis Adobe. Jack Hallin, chief of project development for the agency, said an alternative project suggested by the homeowners would also bring increased traffic into Old Town Calabasas.

“There is going to be development in that area, and we’re going to have to figure out the best way to handle it,� Hallin said.

Attorneys for the four organizations filed a lawsuit in Los Angeles Superior Court earlier this month, saying that Caltrans violated federal and state environmental quality requirements when it approved the project without preparing a report or even an environmental impact statement, which is typically less detailed than a complete impact report.

The Leonis Adobe Assn. filed a similar suit in U.S. District Court last December against the California Department of Transportation, the U.S. Department of Transportation and the Federal Highway Administration, all of which are involved with the project.