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Facing another drought and a teetering basin, Los Osos will investigate new water sources 

Los Osos' only source of drinking water is still threatened by seawater intrusion after six years of work trying to reverse the trend.

click to enlarge WRONG DIRECTION Three important metrics to measure the health of the Los Osos Valley Groundwater Basin show troubling trends. While nitrate levels are dropping steadily, chloride levels (salt from seawater intrusion) are increasing. None of the metrics have reached their target levels. - DATA COURTESY OF THE LOS OSOS CSD/GRAPHIC DESIGNED BY ALEX ZUNIGA
  • DATA COURTESY OF THE LOS OSOS CSD/GRAPHIC DESIGNED BY ALEX ZUNIGA
  • WRONG DIRECTION Three important metrics to measure the health of the Los Osos Valley Groundwater Basin show troubling trends. While nitrate levels are dropping steadily, chloride levels (salt from seawater intrusion) are increasing. None of the metrics have reached their target levels.

Chloride (salt) levels in the coastal basin were 27 percent higher in 2020 compared to 2019, and 41 percent higher than in 2018. If the metric jumps another 25 percent, it would be above the threshold that's acceptable for public drinking water.

Given that lack of progress, and now the new drought, Los Osos Community Services District (CSD) General Manager Ron Munds believes Los Osos needs to start looking at new sources of water for the first time.

"We need to be looking outside," Munds told New Times.

On Sept. 9, the Los Osos CSD's board of directors received a presentation on the status of the basin and then voted unanimously to authorize Munds to begin investigating new possibilities for water.

"I've always had a concern about the viability of our groundwater basin long-term," said Munds, whose career in municipal water includes 27 years with the city of San Luis Obispo. "Where will the groundwater basin be in 30 years or more? What's our plan B?"

Currently, Los Osos has no plan B if the basin fails.

In 2015, SLO County Superior Court approved a plan that aims to salvage the aquifer that stretches from the Morro Bay estuary to the inland valley farmland. It's trying to reverse two dangerous trends: nitrate pollution in the upper aquifer, which was caused by septic systems; and seawater intrusion into the lower aquifer.

The key strategies in the plan, according to Munds, are to shift pumping from the lower aquifer to the upper aquifer, which is improving since a new sewer plant was built, and to move production wells away from the coast to address seawater intrusion.

Yet despite the years of work and a few completed projects, a 2020 annual report on the basin showed meager progress and even a backslide on chloride.

"We're six years in, and the timeline [for the plan] was 10 years. ... We're not seeing the results we expected," Munds said. "It's being exacerbated by drought—conditions that I think we'll see more and more of."

Munds noted that the impact of climate change on the basin isn't just about drought. Even in wet years, storms are expected to get shorter and more intense—he called them "gushers"—which won't provide as much opportunity for rainwater to percolate into the ground.

Basin projects are expensive and take time to design and execute. While it's still too early to call the plan a bust, Munds said it's prudent to start considering alternatives now. He recalled the city of SLO's efforts to diversify its water portfolio following the drought of the late '80s and early '90s.

"At the end of the day, if it doesn't make sense, it doesn't make sense, either from a water supply standpoint or a cost standpoint, or both," Munds said of new sources. "But until we do our due diligence, we have a responsibility to provide options to the community."

One of the options Munds is exploring for supplemental water is a possible Los Osos connection to the State Water Project, which terminates in Morro Bay. The distance from Los Osos to Morro Bay's system is 2.7 miles, which doesn't sound far until you start calculating costs.

"I know it costs about $200 per foot to build a pipeline," Munds said, indicating a $2.9 million price tag for construction. "Cost is going to be huge factor, there's no doubt about it."

Capacity would be another factor. This year, the State Water Project is delivering at only 5 percent capacity due to the drought. On top of that, state water infrastructure in SLO County is limited by pipeline capacity. Munds recently met with public works staff at SLO County to discuss these issues, and he plans to meet with Morro Bay officials next.

Complicating Munds' investigation is the new Los Osos Community Plan, a long-awaited document that charts the town's growth over the next 20 years. The plan, which still needs approval from the California Coastal Commission, envisions lifting a building moratorium and increasing Los Osos' population by 30 percent—if the water supply is there.

Right now, that's a big if. The three Los Osos water purveyors—the CSD, Golden State Water, and S&T Mutual—have repeatedly warned that they're concerned about the current health of the basin and its ability to serve even the current population.

"For existing customers, we could run into problems just seeing how tenable the situation is when we have these multiple drought years," Munds said.

As the CSD investigates the possible alternatives, Munds encouraged members of the public to pay attention and get involved. He said the process is in its early stages.

"This will be very transparent," Munds said. "We'll definitely be listening to all comments and all information as it comes in. Nothing is a done deal." Δ

Assistant Editor Peter Johnson can be reached at pjohnson@newtimesslo.com.

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