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Lake Hennessey water treatment (copy)

The Napa County Grand Jury said Napa Valley water providers need to do more to control for taste-and-odor complaints.

A grand jury investigation concludes that residents in Napa County’s cities can drink tap water without fear of contaminants, though they might sometimes find the taste hard to swallow.

Local cities should pay more attention to taste and odor complaints, the new 2018-19 grand jury report said. It urged cities to better communicate with the public on the topic and consider improving water treatment.

Each of the county’s cities must respond to the grand jury report within 90 days of receiving it.

Drinking water meets state and federal quality standards and is safe to drink, the grand jury concluded. But taste and odor is another matter, with problems potentially arising from residual algae amounts as small as 10 parts per trillion in treated water.

This is the equivalent of 10 drops of algae-laced water in an Olympic-size swimming pool and people with sensitive taste can notice it, a local public works official told the grand jury.

The city of Napa during 2017 logged 62 formal complaints about taste and odor and color problems with water, most of them due to Lake Hennessey reservoir algae issues, the grand jury report said. The report quoted from the city’s complaint log.

“Customer complained of terrible taste and odor in water. Husband said was earthy, wife thought it was metal. Explained water meets all regulations and is constantly tested. Hung up happy? Resolved over phone,” said one complaint entry.

“Water tastes like pond water. Undrinkable. Suggested to put it in the refrigerator, the colder it is, the better,” another said.

“Customer is complaining of strong odor, complains chlorine smell has gotten worse ... she is not happy,” another said.

The city of Napa takes water from its Lake Hennessey reservoir in the mountains east of Rutherford, smaller Milliken Reservoir east of Silverado and the State Water Project’s North Bay Aqueduct, which carries Sacramento-San Joaquin Delta water. Each source has its own water treatment plant.

Lake Hennessey can experience algae build-up, especially in late summer, the grand jury report said. The algae is present throughout the lake at all water levels, making pre-treatment difficult. The water treatment plant has a permit to apply aquatic pesticides close to the intake tower to control algae entering the plant.

The city of Napa could upgrade the Lake Hennessey treatment plant to better deal with taste-and-odor issues. But city Water General Manager Joy Eldredge said options such as ozone would cost millions of dollars for capital costs and have higher operational costs. This is a hot-button issue nationwide, she said.

“Do we spend the money for this particular problem that does not pose a threat, but is aesthetics?” Eldredge said on Monday.

Many of the taste and odor complaints are from people who have recently moved to the area, Eldredge said. For example, somebody might have come from San Francisco, which has the high-quality water source of Hetch Hetchy Reservoir in the Sierra Nevada.

Napa County and the city of Napa are working on a Lake Hennessey watershed study to look at runoff into the reservoir. Such things as nutrients from fertilizer can cause algae growth. That raises the possibility of trying to keep nutrients under human control out of the lake by stopping them at the source, if that proves to be a problem.

“The best thing to do is protect that water quality as best we can,” Eldredge said.

North Bay Aqueduct water from dead-end Barker Slough in the Delta is notorious for water quality problems. The grand jury report said the city of Napa in 2012 spent $38 million to improve its water treatment plant in Jameson Canyon for this water source.

The grand jury recommended cities to advise citizens of known and anticipated taste-and-odor and color issues. It recommended cities publish taste-and-odor and color quality measures and results as part of their annual water quality reports provided to citizens.

Local jurisdictions should evaluate water treatment upgrades to turn out more aesthetically pleasing water, the grand jury recommended. But it also acknowledged the money challenge.

“While more might be done to make the water consistently taste better, such improvements come at significant cost,” the report said. “County residents, especially upvalley, already pay high rates for safe drinking water and wastewater.”

A household in Calistoga or St. Helena might pay more than double the cost for water and wastewater as a household in the city of Napa, American Canyon or Yountville, or $1,000 to $1,500 more annually, the report said.

Each city in the county manages its own water supply and charges rates to a relatively small population base. That’s a legacy of a rural history of city-by-city self-funding and self-management, the report said.

Potential solutions the grand jury wants explored include sharing water treatment resources among jurisdictions and perhaps even creating a countywide water provider. The Local Agency Formation Commission of Napa County plans to do such a study that could result in recommendations by February.

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Napa County Reporter

Barry Eberling covers Napa County government, transportation, the environment and general assignments. He has worked for the Napa Valley Register since fall 2014 and previously worked 27 years for the Daily Republic of Fairfield.