In 1987, a century after its founding, the Turlock Irrigation District started to look at providing drinking as well as farm water.
A quarter-century has passed without a treatment plant being built, in part because of concern about water bills in the cities that would pay for it.
The project – which in its current form would serve Turlock, Ceres and south Modesto – has gained traction as these cities deal with concerns about their groundwater supplies.
TID will hold a pair of meetings next week at which the public can comment on whether it should sell some of its Tuolumne River supply to the cities.
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The project would be similar to what the Modesto Irrigation District has done for nearly 20 years for the parts of Modesto north of the Tuolumne. Officials say its river treatment plant has reduced reliance on wells and helped recharge the city’s aquifers.
“Having groundwater and surface water is a good portfolio for a city to have,” said Garner Reynolds, regulatory affairs manager for Turlock.
The proposed plant has an initial cost estimate of $150 million, said Steve Stroud, general manager of the Stanislaus Regional Water Authority, formed by the three cities to pursue the project. It could take six to seven years to complete, including environmental review, permitting, design and construction, he said.
The cost could be higher and the timeline longer if the partners have to get water from a supplier other than TID, Stroud said.
The district has indicated support for the project, which could improve a regional groundwater basin used by farmers and city dwellers alike. But TID also faces the prospect of reduced river water over the long term because of state and federal proposals to boost flows for salmon and other fish. This year’s severe drought, which has cut farm deliveries to about 40 percent of average, adds to the unease.
“TID’s mission is to serve our current customers safe, reliable and affordable irrigation water and power,” spokesman Calvin Curtin said by email. “As with any decision regarding competing demands for a limited resource, striking the right balance is a key decision-making component.”
TID and MID long have sold untreated water to farmers at fairly low cost. To make it fit for domestic uses, it must be cleansed of the contaminants, mainly microbes, that enter the river as it flows from the Sierra Nevada. It’s an expensive process, but the cities also face the cost of treating individual wells to meet state and federal standards.
The plant is proposed for a TID-owned site close to where Geer Road crosses the Tuolumne. In 2001, the district completed an intake in the riverbed that could be used to draw water for the plant. Treated-water pipelines would run to Turlock, Ceres and south Modesto. All are within TID’s service area, which covers much of southern Stanislaus and northern Merced counties.
The initial project in the late 1980s also involved Hughson, Denair, Keyes, Delhi and Hilmar, but they have dropped out over the years.
Backers of the current project said it could benefit salmon, since some of the farm water now diverted near La Grange would flow an additional 25 miles to Geer Road.
“We’d like to see these kinds of creative solutions implemented that can have win-win outcomes,” said Patrick Koepele, executive director of the Tuolumne River Trust, in an email. He said fish would not gain if the treatment plant simply drew from the current flow at Geer, which the group believes is too low for spawning and other needs.
Another issue has complicated the project in recent months. TID has asked Turlock to provide highly treated water from its sewage system to make up for some of the river supply. The request drew protest from the Del Puerto Water District, which plans to use the same wastewater for its farmers along Interstate 5 between Vernalis and Santa Nella.