Local water officials this week took steps to flush dangerous nitrates from aquifers near Oxnard in an attempt to bring drinkable water to 200 rural residents who have been forced to rely on bottled water.
But officials predicted that contamination could spread from the El Rio neighborhood to wells to the north and east if drought conditions persist, boosting the concentration of nitrates there.
Nitrates have been linked to "blue baby syndrome," a fatal illness that deprives infants of oxygen.
"The problem could affect all the water companies from El Rio to Saticoy," said LaVern Hoffman, a hydrologist with the Ventura County Public Works Department. "We're talking about more than a couple of thousand people."
Warning Last Year
Of concern is water in Nyeland Acres, an unincorporated area between Oxnard and Camarillo, where about 300 residents last year were warned not to drink tap water after elevated nitrate levels were detected in a well, said Steve Chase, an aide to County Supervisor Susan Lacey, who represents the area.
While elevated nitrate levels have not been detected so far this year in the Nyeland Acres Mutual Water Co.'s single well, water officials said they will be keeping a close eye on it, the El Rio Mutual Water Co.'s well and those run by seven other small companies as the drought progresses.
Especially critical are the seven months until the next rainy season. That's the earliest that water levels in Lake Piru, the only body of water available to dilute contaminants in Ventura County's underground reservoirs, could increase substantially, say officials with the United Water Conservation District, which oversees the lake.
After three years of drought, Lake Piru has dropped to about half its normal level. It will drop even more as some of its water is channeled into the battle against nitrates in El Rio.
The United Water Conservation District this week began releasing as much as 8,000 acre-feet of water--or roughly the amount the lake received this year in rain and runoff--to a settling pond in northwest El Rio, less than a mile from the well with elevated nitrate levels.
"We've already spent our savings account," said Ron Morgan, a United Water hydrologist. "All we have left is what's in our checking account and we're using that as it comes in."
Sources Are Wastes, Fertilizers
The predicament underscores the severity of the county's problem with nitrates, a component of fertilizers and human waste, which can leach from fields and septic tanks, county officials said.
"Nitrate problems have been with us for a while but now they're really widespread," Morgan said.
Nitrate contamination already threatens more than half as great an area as salt-water intrusion, a water-contamination problem that has received much attention locally, water officials said.
While officials have focused concern on saltwater invading underground reservoirs beneath a 23-square-mile area, nitrates have contaminated underground reservoirs beneath a 13-square-mile area, half of it in El Rio, Morgan said.
Nearly 100 of the 500 wells on the Oxnard Plain "are affected or have the possibility of being affected by high nitrate levels," Hoffman said.
Even United Water, which sells water to municipalities, has found elevated nitrate levels in some of its wells that supply Oxnard, Port Hueneme and the U. S. Navy's Construction Battalion Center and Pacific Missile Test Center, Morgan said. But the company has been able to dilute the contaminated water with cleaner sources to maintain levels within federal standards, he said.
El Rio Mutual Water Co., the customer-owned water company that supplies a six-block neighborhood on El Rio's westside, hasn't been so fortunate. With only two wells, one of which is so contaminated with nitrates that it has been long out of use, the company had nowhere to turn when water samples taken late last year began to show elevated nitrate levels.
Safe Levels Exceeded
Since then, nitrate levels as high as 93 parts per million have been measured in the west El Rio well near Vineyard Avenue and U.S. 101, said Diane Eastman, a water program specialist with the county Environmental Health Department, which is monitoring the well. Levels above 45 p.p.m. are unsafe, according to state and federal standards.
Nitrates pose a risk to babies, who don't have stomach acids to break down the mineral. The unaltered nitrates hamper the blood's ability to transport oxygen.
"The baby can breathe, but doesn't get any oxygen," Eastman said.
For the past five months, officials have warned customers of El Rio Mutual Water not to use tap water in mixing baby formula or juice. They say boiling the water, a step that would kill bacteria, will only aggravate the problem by increasing the nitrate concentration.
El Rio Mutual Water President Al Gonzales said this week that he was looking into the possibility of buying equipment to treat the water or mixing the contaminated water with cleaner sources from other water companies. "I'm concerned because I also live here," he said.
However, such steps are expected to be too expensive for the 110 low-income households that make up the company, officials said.
Hydrologist Morgan said the county will have to consider taking steps to solve the problem countywide.
"In the past, you could just put a filter or treatment facility at your water supply, but that doesn't help the regional problem. We're having to take a more holistic look."
To that end, the United Water Conservation District plans this summer to begin a $75,000 study of nitrate contamination and possible remedies.
But county officials will have their work cut out for them, according to a hydrologist who has studied nitrate removal systems.
"To remove nitrates from the water is very costly," said Steve Mains, who works for the Western Municipal Water District in Riverside County. "This is new stuff. It's not off-the-shelf technology. You have to design everything yourself."
In the meantime, officials said they believe that nitrates are being released into the soil either by fertilizers used on strawberries--a crop that requires much fertilization--or by waste leaking from septic tanks.
Not on Sewer Lines
Many farmers in the El Rio area have recently switched from citrus crops, which require less fertilization, to strawberries. Households in the unincorporated area are not hooked up to sewer lines.
Aquifers beneath parts of El Rio, Nyeland Acres and unincorporated areas around Santa Paula, Ojai, Fillmore and Piru are especially susceptible to nitrate contamination because they are not protected by natural clay caps that prevent contaminants from entering the water supply from elsewhere in the county, officials said.
The El Rio area may have been hit first because underground reservoirs are more shallow and its well is close to a former cattle ranch, where animal droppings may have introduced additional nitrates into the water.
Drought has made the problem more severe.
In a normal year, underground reservoirs between El Rio and Saticoy receive 50,000 acre-feet of water, but this year they received only 13,000. The diversion by United Water is expected to bring the level to between 18,000 and 20,000 acre-feet, depending on the amount lost to seepage along the way.
"We have no way of knowing whether it will help the problem, but it's the least we can do," Morgan said.