More than 20 residential wells in Boonville found contaminated

Nearly two dozen private residential wells in Boonville have tested positive for bacterial and nitrate contamination, providing fuel for an effort to modernize the rural town’s septic and water systems.

The contamination was uncovered during a survey of 23 wells by the Anderson Valley Community Services District, which is exploring funding options for establishing a municipal-style water and sewer system. Tests last week revealed 21 of the wells are contaminated with coliform bacteria and nitrates.

“It’s shocking, how bad it is,” said Valerie Hanelt, chairwoman of the community services district.

But it’s not that unusual for wells on small lots and in close proximity to septic systems to become contaminated, especially when they’re decades old and don’t meet current construction standards, said Mendocino County Public Health Officer Constance Caldwell. Similar problems have been reported in other rural areas that rely largely on older wells and septic systems, including along the Russian River in Sonoma County.

“This is not at all surprising,” Caldwell said.

In the Central Valley, well contamination with nitrates - presumed to be from agricultural operations - is rampant.

No illnesses have been reported in connection with the Boonville wells, but the contaminated water should not be used to make infant formula, health officials said. Caldwell warned that boiling water may reduce bacteria but it can actually concentrate nitrate levels. High nitrate levels have been known to cause methemoglobinemia or “blue-baby” syndrome, a potentially fatal infant blood disorder caused by a reduction in the oxygen-carrying capacity of blood. Seven of the Boonville wells tested at or above the maximum level of nitrates that would be allowed in public drinking water.

Nitrates are associated with both septic systems and fertilizer use.

In addition to being located near septic systems, some of the wells that were tested are located in a section of Boonville known to have marijuana cultivation.

Some of the wells also tested positive for E. coli. Coliform bacteria can indicate the presence of fecal contamination and cause diarrhea.

Caldwell said they are usually harmless but it can mean that feces and harmful germs have found their way into water systems.

No one has recently reported any illness associated with drinking the water from those wells. Adults who regularly consume coliform contaminated water can build up a resistance and may not become sick, health officials said. The contaminants are most harmful to children.

Anyone concerned about the quality of their well water should arrange to have it tested by an independent laboratory , officials said. Testing kits have been made available at the Boonville Fire Department.

Government agencies are not responsible for testing private wells so the extent of contamination is unclear.

They do, however, test water at restaurants, hotels and other commercial ventures at least once a year as part of their regular facility health checks.

“I have no reason to believe there are any problems,” Environmental Health Director Dave Jensen said. Nevertheless, he said, his department will be making sure all the Anderson Valley inspections are up to date.

The survey tests that revealed the contamination were conducted as part of an effort to tap into water funds made available by Proposition 1 in 2014, said Hanelt, “We have suspected for a very long time that there are issues with contaminated drinking water” because there are many small lots in the main section of town, she said.

The first step is to get money for further studies, she said. Before anything is built, there will have to be public hearings, which are likely to be feisty, based on past history.

In the past, Anderson Valley residents have voted down a proposal to build a water reservoir, largely because they worry it would induce growth and alter their beloved town, Hanelt said.

Evidence of contamination could make area residents more amenable to the idea of building water and septic systems.

“The community service district has proven there is an issue,” Jensen said.