Napa County wants to find out what it knows and what it doesn’t about its underground aquifers, and is drilling through the data to get a clear assessment of the water supply under the heart of the valley.

Napa County has hired an engineering firm, Luhdorff & Scalmanini of Woodland, to go through the groundwater data and try to paint as full a picture of the water supply as possible from what might be sketchy information. The project is expected to take between seven months and a year and cost around $230,000.

What the engineers find could result in policy changes. Maybe the county will have to drill monitoring wells or ask private landowners if they would volunteer information or allow their wells to be monitored.

Jim Lincoln, chair of the natural resources committee at the Napa County Farm Bureau and vineyard manager for Beckstoffer Vineyards, said people get really nervous when you start talking groundwater, even studying groundwater. “They believe the next logical step is groundwater regulations, and that frightens a lot of people,” he said.

But Lincoln said he believes the more information available, the better. “If there had been better information in the MST (Milliken-Sarco-Tulocay) and Carneros, maybe we could have made better land-use decisions,” he said.

Lincoln believes sharing information and landowners working together is critical to helping solve their underground water problems in the MST, where the county and property owners are considering building a recycled water pipeline for agricultural uses and other options. “Their wells are not doing so good and they see working together is helping,” he said.

Lincoln said that if a continuous picture of the county’s groundwater situation had been maintained since the 1960s, when vineyard plantings began to intensify, it probably would have resulted in better planning and conservation of water.

“I see this (first phase) as positive. Everyone just needs to be careful of people’s property and water rights. But we can’t be afraid of information,” Lincoln said.

Felix Riesenberg, principal water resources engineer for Napa County Public Works Department, said there is a lack of understanding of the current groundwater conditions up and down the valley.

“This particular effort is not to quantify, but is effort to understand the behaviors of the ground water basins,” Riesenberg said.

He said some people are concerned about an overdraft — when more water is removed than is replaced in an underground aquifer. “That does not seem to be the case in the main Napa Valley basin,” he said. “But every so often there seem to be issues in very specific locations.”

Riesenberg said it is clear that MST is a deficit groundwater area, and that information is sketchy in Carneros — where there is a push to obtain recycled water. “We hear about Carneros, but it is hit or miss. They have issues from time to time and yet we don’t have any data out there,” Riesenberg said.

With a comprehensive study, “in the future the county can address issues more proactively. The goal is to improve our overall groundwater knowledge in the county. “People fear management (of groundwater), but that is not what this is about at this point.

The underground aquifers the county is focused on include the main basin on the valley floor, Carneros, MST, American Canyon, Angwin-Deer Park area, Pope Valley and Chiles Valley. “Primarily we want to look at areas where there are populations and developed agriculture,” Riesenberg said.

“If you don’t know what is going on, you won’t know if you are having a problem later on,” Riesenberg said. “We need to know the history to make a sound decision.”