A pipe installed recently to divert storm runoff from Aliso Creek became clogged with grass Thursday, causing about 12,000 gallons of untreated water to back up and flow into the creek it was designed to protect.
"I'm furious," said Roger Von Butow, chairman of the Clean Water Now Coalition, an environmental consulting firm he describes as a watchdog of the south Orange County watershed. "I told them this system would fail, and now it has."
Von Butow said he had told local officials the pipe did not have adequate holding capacity.
Ken Montgomery, public works director for Laguna Niguel, said city workers expected to clear the pipe by the end of the day Thursday.
"Somebody must be dumping a lot of grass clippings into the gutter and hosing them into the storm drain system, because we just cleaned this strainer on Tuesday," he said. Ordinarily, Montgomery said, the strainer needs cleaning once every two months.
Runoff into the creek from neighboring housing developments has been an ongoing issue. Water tests conducted in the summer and fall of 1999 showed unusually high bacteria counts. The San Diego Regional Water Quality Control Board that December ordered the city to abate the pollution. In response to the order, Laguna Niguel built the runoff diversion system in May.
The environmental damage caused by Thursday's overflow was minimal, Montgomery said.
"This is not a dirty storm drain," he said, adding that recent tests of the runoff indicated bacteria levels only slightly above the legal limit. "The storm water in this system has been getting really clean over the past few months. It's really not all that polluted."
Some disagree, however, pointing to testing in November that indicated the presence of the virus that causes Hepatitis A.
Montgomery said further testing for the virus was negative.
Times staff writer Tina Borgatta contributed to this report.