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SSJID’s Solid Financial Health Aided By Tri-Dam
ssjid dam
Donnells Reservoir is on the middle fork of the Stanislaus River with its crest at 4,921 feet.

Numbers don’t lie.

The Tri-Dam Project is arguably the most powerful force that has shaped the economic success of the “Almond Triangle” of Manteca-Ripon-Escalon.

It is why South San Joaquin Irrigation District has $92 million in reserves of which $50 million are earmarked for future expenditures such as capital improvement projects and paying down the shortfall in unfunded retirement costs.

But it is also a key contributing factor to the economic success of hundreds of family farming operations as well as the three cities within the district.

And it goes way beyond simply being able to capture superior and legally adjudicated water rights to the Stanislaus River watershed that provide 300,000 acre feet of water a year to irrigate orchards, grow crops, and send water flowing through faucets.

The Tri-Dam project generates more than 130 megawatts of electricity a year. On an average the wholesale power generated brings in $20.72 million that is split 50-50 with SSJID’s Tri-Dam Project partner, the Oakdale Irrigation District.

That translates into an average of $10.36 million a year for SSJID.

Without that money, irrigation water for farmers as well as water treated for urban use in Manteca, Lathrop, and Tracy would be significantly higher.

Not having Tri-Dam revenue would have a devastating impact on farmers and urban households alike.


Balanced budget for

2021 is the latest in

a long string for SSJID

The SSJID board last month adopted yet another balanced budget for a decades long string that is only broken periodically when drought years reduce electricity generation and trigger the need to dip into reserves.

The 2021 operating expenses are $33.4 million. Without Tri-Dam revenue, there would be an $11.4 million shortfall. The only way to cover that gap with Tri-Dam revenues is through higher property taxes and/or higher irrigation and water rates. Irrigation and treated water sales are anticipated to bring in $11.7 million this year. That would mean if water sales to farmers and cities in-district were used to make up for the loss of Tri-Dam revenue that revenue source would have to double meaning significantly higher rates.

The $11.4 million figure as SSJID’s share of Tri-Dam power sales for 2021 is conservative due to the potential for dry hydrology on the Stanislaus River watershed.

Tri-Dam revenue also finances capital improvement projects such as the upcoming main tunnel replacement.

Power sales do fluctuate based on available water. In recent years the SSJID’s annual share has ranged from a low of $4.38 million in 2015 at the depth of the most recent drought to $15.79 million in 2020. The Tri-Dam project has benefited by being able to tie increased Sand Bar hydro production into the current power purchase agreement with Silicon Valley Power based in Santa Clara.

That means a dam built essentially by farmers 64 years ago now literally powers an Intel semi-conductor plant; hence computers powered by Intel are using chips produced using electricity generated by Tri-Dam harnessing water on the Stanislaus River.

The district always budgets for a worst case scenario given power sales revenue fluctuates. This year’s worst case scenario budget projects $4.6 million less than the $11.4 million in Tri-Dam revenue projected if snowfall in the Central Sierra ends up being substantially below average. If that happens, the district simply dips into its $42 million of unassigned reserves which is essentially money squirreled away from heavy electricity generation years.

If the district today did not take in another dime and did not start capital improvement projects money has been set aside for, they have enough cash on hand to cover 100 percent of the operational costs for almost eight years.


Tri-Dam Project was

built during the 1950s

Plans for the Tri-Dam Project were drawn up in the 1930s consisting of three dams — Donnells, Beardsley, and Tulloch — as well as three power plants and a seven-mile tunnel carved through rock.

Construction didn’t start until 1955. When it was completed SSJID had three times the water storage than what the original dams provided at (Old) Melones and Goodwin. They also had a reliable source of income to pay for the system’s operations and maintenance as well as to retire bonds over 50 years.

Financing for the $52 million project was secured when Pacific Gas & Electric signed a contract with the two districts to buy electricity from the three dams through 2005. Power sales at a rate established in 1955 essentially gave the two districts money to pay for the dam with additional cash to operate the system and help assist with improvements in their respective districts. Since the project was paid off and the PG&E contract ended, the districts in some years have split almost as much as $21 million to fund upgrades to water delivery systems as well as enhance power generation capabilities.

The project took less than three years to build. It was dedicated on June 15, 1958 at Beardsley Dam.


Three dams all built

without any funds from

state or federal sources

What was considered remarkable at the time — and even today — is the fact the Tri-Dam system was planned, financed, and constructed entirely by SSJID and OID without a penny from the state or federal governments.

When Donnells was completed in 1958 it was the fifth highest concrete arch dam in the western United States with an exposed dam face of 317 feet. It was topped by Hoover Dam at 726 feet built in 1936, O’Shaughnessy Dam in Yosemite National Park at 430 feet built in 1923, Arrowrock Dam on the Boise River at 350 feet built in 1915, and Parker Dam on the Colorado River at 320 feet built in 1938.

The advantage of a double arch concrete dam is they get stronger as you put more water behind them.

That’s why Donnells peak water elevation is 4,916 feet — a foot below the top of the dam. Other dams such as the earth-filled Beardsley Reservoir that is part of the Tri Dam Project have ultimate water elevations significantly lower than the top of the dam. At Beardsley the top water elevation is 3,297 feet as opposed to the dam’s elevation of 3,405 feet.

Donnells holds 64,325 acre feet of water but was at 23,820 acre feet as of Jan. 11, which is 130 percent of average for that date. Beardsley holds 97,802 acre feet of water. It was at 29,476 acre feet on Jan. 11, which is 73 percent of average for that date.

Tulloch Reservoir holds 64,332 acre feet of water behind a dam with an elevation of 5007 feet. As of Jan. 11 it was at 34,758 or 63 percent of average for that date.

Tri Dam is headquartered in Strawberry off of Highway 108 in Tuolumne County.


Tri-Dam will make

cheaper electricity possible

in Manteca, Ripon & Escalon

The Tri-Dam proceeds allowed SSJID to conduct four years of capital improvement projects into one year to take advantage of lower construction prices during the Great Recession and generate jobs, install state-of-the-art drip irrigation systems in Division 9 south of Manteca, and to fund undertakings such as research to protect the fish on the Stanislaus River.

It has also covered the hefty bills SSJID has piled up pushing toward its goal of harnessing Tri-Dam proceeds to lower electricity rates 15 percent in Ripon, Manteca and Escalon. That could become a reality this decade as SSJID deals with the final stretch of legal obstacles to acquire the retail system from PG&E.

Independent consultants hired by the San Joaquin County Local Agency Formation Commission analyzing the SSJID retail power plan emphasized the Tri-Dam receipts is what makes it possible for the SSJID to accomplish its goal of lower power rates across the board 15 percent.

The vision from the start when the SSJID was formed and steps were first taken to secure and then harness adjudicated legal water rights that are senior to others in the basin was to use water to power the economic growth of the South San Joaquin County.

After Goodwin Dam was built and irrigation water deliveries started in 1914 with the first water arriving in the Manteca area to a farm near where Calla High is today on Austin Road and East Highway 120, the first wave of economic prosperity swept through Manteca and other SSJID communities. With the arrival of irrigation water in 1914, Manteca farming and the community itself more than tripled in five years.