The city and the U.S. Fish and Wildlife Service are investigating whether grading work and a 25-foot-high earthen dike built in the San Joaquin Marsh violate city and federal laws.
The Irvine Ranch Water District destroyed wetlands when it flattened and filled in about five acres on the west end of its Michaelson Wastewater Treatment Plant property, fish and wildlife biologist Kim Falzone said.
"The extent of the damage is still being investigated," Falzone said. "We do consider it something serious."
The Fish and Wildlife Service has asked the Army Corps of Engineers to order the water district to halt further activity in the wetlands area, remove about 5,000 truckloads of dirt and restore the native plants. The corps, which oversees and enforces some of the federal laws safeguarding wetlands, will investigate, a spokeswoman said Tuesday.
Irvine officials are examining the grading project to determine whether it violates city codes, said Steve Haubert, a principal planner with the city Community Development Department.
Haubert said it appears the water district should have submitted the project to the Planning Commission for review and should have followed the California Environmental Quality Act review process before beginning work. The matter has been turned over to the city attorney for review.
Ronald Young, general manager for the Irvine Ranch Water District, said he doesn't believe the grading work required city, state or federal approval. But the work has been suspended until regulators make their determination. "Once that happens, we'll understand what the problem is and we'll do everything we need to do to make it proper," Young said.
The clearing work began about two or three months ago in an effort to create a flat area for a proposed composting project, Young said. The project would mix grass clippings and other landscape waste with sewage to create compost, he said.
Irvine is considering an ordinance to require landscaping to use less water. The compost, which conditions the soil and helps reduce evaporation, would fit in with the proposed ordinance as well as reduce the amount of landscape waste going into landfills, Young said.
"We think we're a very environmental agency," he said. "We're not out to damage anything. We're trying to balance everything."
The 1,000-foot-long dike was built to screen the sewage-treatment works from several housing and commercial projects being built or planned along Carlson Avenue on the west side of the plant, he said. Trees would be planted on the top of the dike, helping to shield the plant from view.
Once people start living near the treatment plant, Young said, water district officials fear there could be pressure to shut it down.
"In order to be a good neighbor, we do our job best when everybody's happy," he said.
But the grading work should not have been conducted in the sensitive marsh area, at least not without first obtaining permits that could have mitigated the damage, Falzone said. The grading destroyed patches of mulefat, a wetlands shrub, and perhaps other plants, she said.
"The scope of the violation is not as serious as some of the violations we've had, but it is substantial," she said. "These (wetland) areas are critical."
Orange County retains less than 10% of the wetlands it had 100 years ago.
Once the Corps of Engineers reviews the damage, it can force the water district to remove the dike and the extra fill dirt and replant the lost shrubs, Falzone said. It also can levy penalties of up to $50,000 per day, she said.