County officials are considering adding treated sewer water to the San Gabriel Valley's scarce ground-water supplies.
A preliminary study shows that the plan would raise the water table by one foot, easing the valley's dependency on an uncertain supply of imported water that is nearly 30% more expensive than treated water, the officials said.
They added that the plan, still in its earliest stages, would not pose any health problems.
Treated sewer water would constitute only 3% of the water pumped out of San Gabriel Valley wells every year, but could make a big difference in the availability and cost of water, officials said.
Release at Azusa
Under the plan, 2.5 billion gallons of treated water would be taken from the county Sanitation Districts' treatment plant in Whittier each year, pumped through pipes along the San Gabriel River and released into the river at Azusa, where it would seep into porous soil at the head of the 170-square-mile underground basin that collects water between the San Gabriel Mountains on the north, Whittier Narrows on the south, the Puente Valley on the east and Alhambra on the west.
It would cost $3.7 million to build pumping facilities and begin monitoring wells, said Kevin Smead of Stetson Engineers, who prepared the preliminary study.
The Main San Gabriel Water Basin agency will conduct a detailed study for the Upper San Gabriel Valley Municipal Water District, said Robert Berlien, general manager of the district.
Using treated sewer water in such a manner is not a new idea, said Earle Hartling, a project engineer with the Sanitation Districts, the agency in charge of treating raw sewage.
"Since 1962 we have recharged the Central (Los Angeles water) basin in the Montebello and Monterey Park areas" with treated sewer water, he said.
'Practice Is Safe'
"We did a four-year study between 1980 and 1984, tracing what happened to people ingesting the water compared with people not ingesting the water," Hartling said. "There was no increased evidence of birth defects, cancer or other diseases over the 22-year period, so we concluded the practice is safe."
Officials said residents have generally accepted the practice. Some water companies have said nitrate contamination in their wells is caused by the treated water, but county officials do not agree.
The quality of San Gabriel Valley water is of increasing concern to federal officials, though the extent of the pollutants, their identity and their sources have not been determined.
The U. S. Environmental Protection Agency, spurred by concern that water contamination has spread to Whittier Narrows--where the course of the San Gabriel River connects the valley's ground-water basin with the central Los Angeles basin--has earmarked $3.85 million to investigate the problem.
The agency is also using $1.95 million from the federal Superfund to combat severe contamination by constructing treatment plants in north El Monte.
Trying to determine how pollutants are getting to Whittier Narrows and pinpointing their source will involve an investigation of the entire San Gabriel Valley ground-water basin, EPA officials have said.
Smead said the San Gabriel Valley now relies on expensive imported water when the ground-water table becomes low.
"Our current sources are the Colorado River and Northern California," he said, "and this costs the water companies, and ultimately the consumers, $153 per acre foot compared to reclaimed water, which is $110 per acre foot." There are 326,000 gallons of water in an acre foot.
The project could not start for at least two or three years, after public hearings, an environmental impact report and approval from the Regional Water Quality Control Board and the state Department of Health Services. Both regulatory agencies support the concept, but final approval would depend on the outcome of the study, officials said.
Forty-six water companies provide drinking water to 1 million people from 400 wells in the San Gabriel Valley basin.
"I haven't talked to any water companies who are opposed to the idea," Berlien said.
"Historically, those opposed to the concept have said there is a risk that something could go wrong in the process of treating the (sewer) water. But it seems to us that we have a limited water supply, and this is a dependable source and it does save money."
The Suburban Water Co., which serves portions of Covina, La Puente, West Covina and Glendora, has taken no position but wants to proceed with the study, said Reg Stone, senior vice president.
"We want to know if it is a viable alternative," he said.
Stone said the study should answer questions about whether the wells, many of which are contaminated with household pollutants, would be adversely affected by treated water.
Although officials of the Sanitation Districts said reclaimed water meets current drinking water standards, Stone and other water company officials said the public would have to be convinced.