How Much Pollution Can the Bay Handle? : Environment: Group wants court to halt ground-water discharge until it’s determined how much the bay can assimilate daily.

Ground-water discharge into the San Diego Bay should be stopped until the Regional Water Quality Control Board determines just how much pollution the bay can assimilate daily, a San Diego environmental group charged Friday.

In a writ filed in San Diego Superior Court, the Environmental Health Coalition claimed that the water board is in violation of the federal Clean Water Act and should revoke the handful of permits it has issued that allow ground water to be dumped into the bay.

About half a dozen permits have been issued by the agency to allow ground water that seeps into the basements and parking garages of several major downtown structures to be pumped into the bay.

Most prominent among them is the San Diego Convention Center, which daily pumps more than 300,000 gallons of ground water into the bay.

Although the San Diego Regional Water Quality Control Board monitors the pollution caused by each of the individual ground-water discharges, the board doesn’t know the aggregate effect of that pollution on the bay, the coalition said.

“The state board has jeopardized the already substandard water quality of San Diego Bay,” said Laura Hunter, director of the coalition’s Clean Bay Campaign. “We need to better understand the effects of new ground-water discharges before they are allowed into the bay.”

The spokesman for the Water Quality Control Board did not return phone calls for response to the allegation.

At issue is a provision of the Clean Water Act that orders the water agency, as an agent for the federal Environmental Protection Agency, to establish the “total maximum daily load” of pollutants that can be assimilated by the bay.

Once that is done, the Environmental Health Coalition claims, the water board will be better able to establish pollution discharge limits.

The Clean Water Act prohibits the discharge of new pollutants into a waterway unless there is sufficient evidence, before a permit is issued, that there will be no unreasonable degradation of the marine environment, the coalition said.

“In the case of San Diego Bay, the impacts of new discharges can’t be proved or disproved because . . . the pollutant load models haven’t been done for San Diego Bay,” Hunter said. “We need to sit down with a judge and the various parties involved . . . and see how we can get this bay properly monitored and protected.”