Agency Says It’s Not Source of Contamination

Armed with the results of a $75,000 internal study, officials from the United Water Conservation District said Tuesday they have proof that their efforts to replenish local aquifers did not contaminate Oxnard’s ground-water supply.

Instead, United’s study--produced over the past several months by United’s hydrologists--attributes the problem to a combination of factors exacerbated by Oxnard’s decision to pump more water out of its aquifer system.

The contamination, specifically a hazardous spike in nitrates, forced Oxnard to shut down four wells in its city pumping yard. The city is now using state water exclusively for its domestic supply.

The source of the contamination has been under question ever since, with speculation lingering on the Freeman Diversion Dam, a conservation project run by United.

“We intend to set the record straight,” said Dan Pinkerton, president of United’s board of directors. “We’ve done a lot of good work here and now we have a cloud over our activities.”

But county water officials questioned United’s conclusions, saying the report did not provide enough data to substantiate its claims and overstated the problems with Oxnard’s wells.

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“There’s an enormous amount of good information in there,” said Art Goulet, director of the Ventura County Public Works Department. “But we think they are extrapolating too much from the data available over the years.

Oxnard officials, who received a briefing on the report Tuesday night, said they needed time to discuss the report with United before commenting. But Oxnard water quality manager Richard Eccles acknowledged he had questions about it.

“The report has some merit,” he said. “But the city has some very serious concerns on some of the data and how it was collected. And on the quality of water from the Freeman Diversion project.”

The spike in nitrate levels--which shot above state levels--raised health concerns for Oxnard’s population. Nitrate contamination, which typically comes from fertilizers or animal and human wastes, can cause fatal oxygen deprivation in children under 6 months as well as severe problems for the elderly.

An environmental consultant hired by Oxnard pointed to the Freeman dam, which traps water from the Santa Clara River near Saticoy. The water is then channeled into spreading ponds in El Rio. Gradually, it is absorbed into the ground, sinking until it enters the layers of aquifers under Oxnard.

The consultant suggested that because the Santa Clara River includes discharges from waste-water treatment plants upstream, nitrates from human waste could be responsible for Oxnard’s well contamination.

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But on Tuesday, United officials said the contamination could be traced instead to poor management of fertilizing in the Oxnard Plain, old septic tanks in El Rio and over-pumping of wells by the city.

What is actually happening, United officials argue, is that abandoned wells--there are reportedly hundreds throughout Oxnard--are sucking contaminates into the aquifer. The abandoned wells act like straws, they said, pulling down water from the semi-perched zone, a layer of earth near the surface full of contaminates including agricultural chemicals. Pumping by active wells then sucks that polluted water back out, explaining the nitrate problem, United officials said.

United used data from various agencies to support its stance that the water the Freeman dam diverts is of good quality and contains only minimal traces of nitrates. Comparing the average amounts of nitrates in samples taken from the river to samples taken from Oxnard’s contaminated wells indicates the river water is not to blame, United said.

“Our conclusion has been that excessive pumping near abandoned wells explains the high nitrate levels,” said Steven Bachman, United’s hydrologist and one of the authors of the report.

But Ventura County officials who had a preview of United’s report earlier this month have some reservations about it. In a letter to Fred Gientke, United’s general manager, Goulet says the data in the report are insufficient to characterize the water quality in the Santa Clara River. “The study characterizes . . . based on as few as two and perhaps three data points,” Goulet wrote.

Goulet’s letter also said United should recognize the possibility that microorganisms from human waste could have entered the river from the upstream sewage plants.

“This is an obvious omission,” the letter states.

Lowell Preston, manager of the agency’s Water Resources Division, said he hopes United will soon begin to collect data on bacterial content of the water it diverts. That data could prove definitively whether the river water is good enough to be put into the Oxnard Plain aquifers.

“My personal opinion is that the water in the river is good,” Preston said. “But we don’t have the data to show it.”

The county also disagrees with United’s claim that leaking abandoned wells are the primary factor for the contaminated ground water. “The focus on leaking wells . . . as the primary cause for the poor quality water appears overstated,” the letter from Goulet states. Preston said the county agrees that the leaking wells are a contributing factor, but that less emphasis should be placed on them. He said leaching septic tanks and over-use of fertilizers are equally to blame.