By RYAN SABALOW  –  Sacramento Bee  –  rsabalow@sacbee.com

After more than six decades of secrecy, the reports that water well drillers file with the state are set to become public under a bill signed into law this week.

But because of privacy concerns, it’s still not clear whether the public will get to see the precise locations of the thousands of wells that pull water out of the ground to irrigate farms and supply drinking water.

This week, Gov. Jerry Brown signed Senate Bill 83, a trailer bill attached to the state budget. It reverses a ban on releasing what are known as well logs to anyone but the well’s owners, government officials and those cleaning up toxic spills. Drilling companies have to file the reports when they create new wells. The reports detail the composition of the subterranean layers the drillers encountered and how far down they hit water.

Water scientists and advocates had long pushed for making the reports public, since they provide critical information about underground features and depth and quality of a water supply. The reports, they say, are even more important now as groundwater increasingly is being overtaxed amid years of drought. About 40 percent of California’s freshwater supply comes from underground sources – a percentage that’s growing as the state’s reservoirs shrivel.

California is the last Western state to make its well logs public. Some states, including Texas, even post them online. The secrecy dates back to the late 1940s, when the state’s well drillers fought to protect prime drilling spots from competitors. The state keeps an estimated 800,000 logs. As water supplies have shrunk, even some well drillers have begun to argue they need to be made public – so they, too, can better understand the state’s aquifers, and where they can find clean water. Jorge Vargas drills a well at a farm in Chowchilla in 2014. Reports that water well drillers file with the state are set to become public under a bill signed into law this week.

Some addresses may be hidden as California well reports become public .  Not everyone in California was happy about the push to open the logs up, however. Some water agencies feared they could be used by terrorists to poison a city’s water supply. Farmers also expressed concern. Danny Merkley, director of water resources for the California Farm Bureau Federation, said Friday that releasing the specific location of a farmer’s wells provides a “road map” for militant animal-rights activist saboteurs, metal thieves and water-waste wary neighbors who might switch off a farmer’s irrigation pumps without permission. SB 83 appears to address at least some privacy concerns. It says the water agency must abide by the Information Practices Act of 1977, which prohibits the release of some types of personal information.

Eric Senter, a senior engineering geologist with the state Department of Water Resources, said Thursday that the names and addresses of well owners would be considered private under that provision, although the well’s location will be identified. So what if the owner’s address and the well’s location are the same.

Senter said his agency’s attorneys are now trying to figure out what can legally be released. “There’s a lot of nuances of how we’ll actually go about that while still protecting personal information,” he said Thursday. Supporters of the law say they hope state water officials will tilt toward releasing as specific information as possible on where wells are located. But they acknowledge that a general description of a well’s location – rather than a specific address – can also help scientists.

Thomas Harter, a groundwater hydrologist at UC Davis, said underground aquifers can be huge and uniform, so it’s not always necessary to know a well’s exact location to get an accurate picture of what’s underground. He said that depending on what’s being studied, approximations of up to a quarter mile from a well can still be helpful. Debi Ores, attorney and legislative advocate for Visalia-based Community Water Center, agreed. She said that even without an exact location of some of the wells, the data in the reports will still be immensely useful in the quest to find clean drinking water. “Even having an approximate location of where there’s a well drawing out safe water could help identify new well locations,” she said. “It’s a lot more than what we currently have.”

Ryan Sabalow: 916-321-1264,