Contaminants from sewage and cow manure are migrating rapidly through the ground water supply of western Riverside and San Bernardino counties, threatening to make water in nearly half of the region's subterranean basins undrinkable within 25 years, a new study shows.
Preliminary results of the $1.2-million study, coordinated by the Santa Ana Watershed Project Authority and released this week, show that the pollution imperiling the upper Santa Ana River basin is spreading more quickly than was previously predicted and will cost millions of dollars to remedy.
"We're going to have to run, run, run just to keep pace," said Gerard Thibeault, executive officer of the California Regional Water Quality Control Board in Riverside. "It's going to be very difficult and very costly to prevent further degradation of the ground water."
Experts have known for years that the vast Santa Ana River basin, the primary drinking water source for more than 1.5 million people, is plagued by contaminants. But the new data paints a particularly bleak picture, suggesting that water in eight of the 19 sub-basins above Prado Dam will not meet the state's safe drinking water standard by 2015.
The primary pollutants jeopardizing water quality are salts and nitrates. Nitrates are particularly alarming because elevated levels can put infants at risk for developing "blue baby disease," a potentially fatal condition in which the blood loses its ability to transport oxygen.
Thibeault said the principal sources of the two contaminants are waste water discharged into the Santa Ana River by sewage treatment plants and the mountains of manure produced by 300 dairies in the Chino Valley.
In recent years, water quality officials have tightened regulations on the dairies, which house about 290,000 cows. New rules have limited the amount of manure that may be spread on cropland, and authorities have cracked down on ranchers who allow water used to wash cows to run off their property.
But such measures do nothing to address the huge volume of contaminants that have seeped down through the soil and into the area's vast ground water basins over the past three decades.
As for the waste water, eight treatment plants discharge 115 million gallons of treated sewage daily into the Santa Ana River. In the past, the river's natural filtration system reduced nitrates in the effluent to safe levels. But growth in the Inland Empire has produced an ever-mounting volume of waste water, and experts say the river's ability to naturally process the nitrogen is overtaxed.
The river's surface water quality is a concern because the waterway flows southwest and ultimately funnels into the ground water basin that serves 2 million residents in Orange County.
The study lays out six alternative strategies for responding to the contamination. None could be accomplished without considerable expense that will probably translate into higher sewer bills for residents.
Thibeault said sewage treatment plants probably will be required to cut allowable nitrogen levels in effluent, and the dairy industry will be asked to contribute to construction of so-called desalination systems that would extract polluted water, cleanse it and then pump it back below ground.
Under one scenario, facilities capable of treating 1.2 million gallons of contaminated water a day would be necessary.
Susan Vander Poel, assistant manager of the Milk Producers Council, said dairy operators would help finance a desalination plant and launch a ground water monitoring program. She added, however, that the industry has been "overburdened with blame" for the contamination.