The cities and Napa County should join forces to form a countywide water and sewer utility district, while municipalities expand their recycled water networks, the Napa County grand jury recommends.

The cities should also fluoridate their water systems, the 2009-2010 grand jury said.

The grand jurors, who investigate all branches of government, probed how water can be delivered to Napa County residents more efficiently and how recycled water can become “an alternative for potable water usage in agriculture.”

To that end, the grand jurors said water and sewer departments in Napa County should be consolidated.

The city of Napa Public Works Department and the Napa Sanitation District should “merge to form a municipality-wide utility department to benefit the city of Napa’s residents and optimize the availability and economics of potable and recycled water,” the grand jurors said.

The grand jury also recommended that “the county, its municipalities, and the (Napa Sanitation District) investigate the benefits to all the county’s residents of a countywide utility district to further optimize potable and recycled water resources.”

Grand jurors urged greater use of recycled water, saying that potable water supplied by the North Bay Aqueduct, the state-owned pipe that carries water from the Delta to Napa and American Canyon, is “unpredictable.”

“All municipalities need to provide long-term water supplies for human, agricultural, and industrial uses. It is unpredictable what level of contribution the (North Bay Aqueduct) will have to the county’s long-term municipal supplies,” the grand jury said. “Increased use of recycled water can mitigate the demand on potable water supplies.”

The grand jurors also noted that no municipal water system in Napa County is fluoridated.

The only waters that are fluoridated are small portions of treated water the city of American Canyon buys from the city of Vallejo.

The grand jurors recommended that the water be fluoridated, citing support from the California Dental Association.

“The decline of tooth decay in the United States during the past (60) years is attributed largely to the use of FLUORIDE,” the grand jurors wrote.

Representatives for the Napa Sanitation District and other jurisdictions mentioned in the report deferred comment until their responses are presented to their boards and city councils.

The responses will be prepared within 90 days of the May 31 report.

Don Ridenhour, Napa County’s public works director, said a response will be presented Aug. 17 to the Napa County Board of Supervisors.

In an e-mail this week, Yountville Town Manager Steve Rogers, wrote that a detailed response to the grand jury report will come before the Town Council Tuesday.

Dan Takasugi, public works director for Calistoga, said the City Council will probably discuss the issue at its July 20 meeting.