Kern County supervisors on Tuesday gave environmental health regulators their blessing to begin the six-month process involved in enforcing the Measure E ban on the land application of treated human and industrial waste.

But the possibility of a court challenge clouds the future of the long-embattled, voter-approved rule that blocks use of sewage sludge on farmland in unincorporated Kern County.

Kern County Public Health Director Matt Constantine said all businesses that receive sewage sludge, also known as biosolids, will be notified that they have six months to wrap up any operations that apply sludge to open ground.

Those businesses include the Green Acres and Honey Bucket farms, where the treated waste is used as fertilizer for non-edible agricultural crops, and composting operations such as Synagro near Taft, Constantine said.

Green Acres currently accepts much of the sewage sludge produced by the city of Los Angeles.

Tom Frantz of the Association of Irritated Residents environmental group argued that composting facilities put sewage sludge on the ground and should also be forced to either enclose their operations or stop taking the sludge.

A representative for Synagro told supervisors that all of the company's compost mixing areas are lined so that the compost doesn't touch open ground and all sewage sludge is received inside a building on a lined surface.

Constantine said he is aware of five businesses that take in biosolids -- including Green Acres, Honey Bucket and Synagro.

He said all the composting facilities will be inspected to make sure they begin complying with the provisions of Measure E.

Measure E enforcement has been on hold since 2006 while its validity was hotly contested in federal court. A federal lawsuit filed by Southern California waste agencies was dismissed late last year but the plaintiffs could re-file on some issues in state court.

Kern County Counsel Theresa Goldner has asked Tulare County Superior Court to re-open a previous sludge case between Kern and Los Angeles County in an effort to resolve state law challenges that Kern expects Los Angeles to file against Measure E.

She said she expects some effort from Los Angeles to block the enforcement of Measure E before the end of the six-month grace period.

John Franklin and Frank Mateljan, spokesmen for the Los Angeles City Attorney's office, said there has been no determination of what Los Angeles will do in this case.

Attorneys are still weighing all the information and going over court documents, they said.