More Osos crossfire



Announcements of vindication abounded late last week as a new groundwater study hit the Los Osos sewer debate.

Opponents of the water board's basin plan hailed the findings as further proof of the groundwater table's relative cleanliness. Simultaneously, regulators declared that the presence of certain chemicals-even in trace amounts-point to some wastewater seepage, thus confirming the source of the nitrates.

Yes, this is the same study.

The Los Osos Community Services District (CSD) commissioned the effort to determine if water from the nitrate-contaminated upper aquifer could mix with water from the legally clean lower aquifer to yield tap water below target contamination levels. Consultant Tim Cleath and his team sampled the five wells from around the basin, checking for a cornucopia of potential pollutants.

Cleath found a handful of chemicals-not yet covered by federal water-purity standards-in very small amounts at certain spots and depths in the upper aquifer. This means that a two-part-lower- to one-part-upper-aquifer blend would fall below target nitrate levels and all other chemicals under the umbrella of the EPA requirements.

However, environmental health specialist Dr. John Vargo described other found chemicals as emerging contaminants-ones facing possible regulation in the future. He went on to dismiss these presences as safety threats, but called for the testimony of an expert toxicologist.

"The amounts of the chemicals that we observed were very, very low," Vargo explained. "Much lower than the amounts of pesticides that would typically be observed in drinking water from areas where there is a lot of agriculture-levels at which the EPA considers safe for drinking water."

The pharmaceutical and cosmetic source of these contaminants nevertheless prompted the water board to draw a correlation between the domestic source of the found chemicals and the nitrates purportedly from the same source. Water board official Matt Thompson called it another drop in a deep bucket.

"There's no dispute that the septics are the source of the nitrates," he said. "There's a tradition of peer-reviewed studies reaching back to the '60s."

Opponents called this connection spurious.

"If tiny amounts of those chemicals indicate widespread nitrate contamination, then a lot of people in Los Osos must have epilepsy," activist Al Barrow joked about one found chemical-an anticonvulsant called carbamazepine.

Some basin-plan opponents maintain that certain soil presences consume the nitrates, but not all chemicals leached from septic systems.

"Nitrates are salts, and they're just as soluble as these pharmaceuticals," the water board's Thompson responded. "The notion that they're being filtered out is scientifically wrong."


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