The agency supplying drinking water to a large swath of South San Diego County is exploring a groundwater desalination project that could reduce or even eliminate the agency’s dependence on expensive county water.
By Jim Hinch, Voice of San Diego
The Sweetwater Authority, which supplies drinking water to a wide swath of South San Diego County, is joining the ranks of local water agencies seeking to reduce their dependence on the San Diego County Water Authority.
Sweetwater governing board members earlier this month voted unanimously to begin laying the groundwork for a major new groundwater project that would involve pumping and desalinating millions of gallons of water per year from a massive aquifer under southwestern San Diego County.
The goal, said agency General Manager Carlos Quintero, is to boost Sweetwater’s homegrown water supplies and free ratepayers from footing the bill for expensive imported county water.
“The county water authority is very expensive compared to local sources,” Quintero said. “We’re trying to keep the water rates lower by relying on cheaper water.”
Quintero said the groundwater desalination project, which could cost as much as $110 million, would enable Sweetwater to source roughly 75 percent of its ratepayers’ current water use from groundwater supplies, with the remaining 25 percent coming from two agency-managed reservoirs on the Sweetwater River.
Sourcing more water locally, Quintero said, would enable Sweetwater to reduce or even eliminate its annual purchase of county water. Quintero said county water costs up to seven times more than Sweetwater’s own supplies.
“Water agencies are always looking for the lowest cost for water,” he said.
Sweetwater’s exploration of alternative water sources comes as other local water agencies voice increasing frustration with the county’s main water broker, which supplies drinking water to most San Diego County households by buying water from outside the county and funneling it to local water agencies through a network of reservoirs and pipelines.
Following a string of expensive infrastructure projects and water deals, the county water authority in recent years has hiked rates it charges local water agencies, forcing those agencies to pass along costs to customers.
San Diego City Councilmembers on Tuesday were set to vote on a painful 63 percent rate increase for city water customers in part to cover the rising cost of county water authority supplies.
One Councilmember recently floated the possibility of simply not paying the county water authority bill. Other local agencies have explored severing their ties to the authority or breaking it up entirely.
Quintero said Sweetwater has no intention of severing its ties with the county water authority. But he said his agency does want to reduce its exposure to rising county costs.
In wet years, Quintero said, Sweetwater’s reservoirs and existing groundwater supplies are sufficient to provide the agency’s roughly 200,000 households with drinking water.
During times of drought, however, the agency must turn to the county for backup, Quintero said. That causes water bills to rise.
The groundwater expansion Sweetwater board members voted to explore earlier this month would involve drilling a series of wells in and around southern Chula Vista and constructing a desalination plant and pipeline to remove salt from the pumped groundwater and send unwanted brine to the ocean.
Quintero said Sweetwater would seek state and federal grants to help offset the project’s cost, including the cost of the feasibility study board members approved earlier this month.
The United States Bureau of Reclamation “indicated that groundwater is a priority for them,” Quintero said. “I hope there’s funding for that.”
Not everyone supports the desalination plan. Former Sweetwater general manager Jim Smyth, who has become a frequent critic of current agency leaders, said he supports the goal of reducing dependence on the county water authority. But he said the desalination plan risks making the same mistake that caused county water authority rates to spike.
“The San Diego County Water Authority has [a desalination plant] and they’re overpaying,” Smyth said, referring to an oceanwater desalination facility that has become an expensive line item in the county water authority’s budget. “This Sweetwater proposal is the same risk.”
Smyth said Sweetwater actually studied a similar groundwater project in 2009 and decided not to pursue it because engineers said too little was known about the extent of groundwater supplies and the cost to pump and deliver desalinated water.
“Fast forward to today, we [still] don’t know what it will cost,” Smyth said. “I…believe it will cost more than imported [county] water.”
Quintero said he was aware of the 2009 groundwater study. But he said much has changed since then, especially the skyrocketing cost of county water.
“We’re at the mercy” of county water authority prices, Quintero said. The goal of the desalination project is to reach a point where “in most years we would not have to buy any water from the county water authority.”
