Builder Investigated Over Stream : Environment: The Sierra Club alleges that Shappell Industries dumped material into the waterway while constructing a sewer line.

A Beverly Hills developer is being investigated on suspicion of illegally altering a Thousand Oaks stream in the course of building a sewer line, a state Fish and Game official said Wednesday.

Wardens, acting on a complaint by the Sierra Club, are expected next week to inspect work done by Shapell Industries on a section of the stream known as the Arroyo Conejo, said Gordon Cribbs, head of the agency’s regulatory patrol.

The investigation could take several weeks, Cribbs said.

Dumping or removing material from a stream or creek bed without obtaining approval from Fish and Game officials violates state and federal laws that protect sensitive wetland habitats.

If Fish and Game officials recommend criminal action against the developer, the case could be referred to the district attorney’s office, Cribbs said.

Environmentalists charge that Shapell may have dumped an undetermined amount of cement and other construction material into the stream. They have asked the state to inspect possible environmental damage in other areas of the project.

“Who knows what else they’re doing down there?� said Cassandra Auerbach, a spokeswoman for the Conejo Valley chapter of the Sierra Club.

Officials at Shapell were unavailable for comment on the investigation.

An agreement between the developer and the city requires Shapell to minimize damage to plants and animals that live on parts of the 1,862-acre ranch.

But the Sierra Club has had an ongoing dispute with Shapell over the developer’s plans to build 1,400 houses and apartments and a 102-acre industrial park on property formerly known as MGM Ranch.

In May, the organization sued the city after the City Council approved an environmental report on Shapell’s planned industrial park that the Sierra Club criticized as inadequate.

The environmental group later settled the suit in return for written assurances that the city would require Shapell to consult with state and federal agencies before building.

Sierra Club officials have also lodged complaints against the city that allege a lack of oversight of the development, a charge city officials deny.

John Prescott, a Thousand Oaks planner on the Shapell project, said the city has not been notified of the investigation.

Prescott said Shapell destroyed plants and graded soil near the Arroyo Conejo several months ago when it began work on a sewer line for a planned housing development located several hundred yards from the stream.

Shapell workers cleared and graded a 50-foot-wide swathe of chaparral to connect their pipe with a city-owned sewer line in the Arroyo Conejo. The city’s approval of the sewer line required Shapell to restore the area to its natural state, Prescott said.

The pipeline is for the first 800 houses that have been approved for construction.

“It was something that had to be done to hook it up,� Prescott said. “I don’t know that they’re required to get any state permit.�

In the past, when Thousand Oaks had to repair sewer pipes located in or near a stream bed, it had to obtain a permit from the state Fish and Game Department, city Utilities Director Don Nelson said.

In 1979, the last time the city reconstructed a portion of its three-mile-long sewer line, it sought a permit to alter wetlands around the Arroyo Conejo.

The city also coordinated the wetland restoration work with Fish and Game officials and local environmental groups, Nelson said.

Tom Maxwell, president of the Sierra Club’s Conejo Valley chapter, said that should have been done with Shapell’s project as well.

“I think we’re waking up the agencies to the fact that they need to watch this town,� he said. “They’ve been busy elsewhere and there’s some violations going on here too.�