The COVID-109 pandemic isn’t slowing work aimed at moving arguably the most cantankerous water project ever proposed in California since voters overwhelmingly rejected the Peripheral Canal in 1982 — the Delta Tunnel Project.

Originally envisioned as twin tunnels by former Gov. Jerry Brown, it has been repurposed as a single tunnel by Gov. Gavin Newsom. It would divert water from the Sacramento River before it enters the Delta and move it underground to a point near the pumps northwest of Tracy. The pumps send water out of the basin and into the California Aqueduct to start its journey to urbanized Southern California and massive farms — including many that are corporate owned — in the Southern San Joaquin Valley.

The State Department of Water Resources is currently preparing an environmental impact report on the project. At the same time they are also seeking all required state and federal approvals.

The project is being sold as a way of guaranteeing that the 50 percent of the water used annually by Californians would not have their flow interrupted in the event a major Bay Area earthquake does damages to Delta levees. Such an event, DWR officials contend could disrupt the flow of water to the Tracy pumps and lead to significant salt water intrusion into parts of the Delta

The tunnel is expected to have a significant impact on the portions of the Northern San Joaquin Valley that depend on water from the Stanislaus, Tuolumne, and Merced river basins to support cities, farming and wildlife uses.

That’s because the water diverted into the tunnel for use in the Los Angeles Basin, large southern valley farms, and some Bay Area cities would not flow through the meandering water ways of the Delta. That would essentially mean salt water would move farther to the east putting pressure on freshwater systems that support fish, birds, mammals, and natural vegetation. It also could increase the salinity of water pumped from the Delta for farming.

In order to counter salt water intrusion in the Delta water agencies that rely on the Stanislaus, Tuolumne, and Merced rivers to support farming and cities such as Manteca, Lathrop, Modesto, Tracy, and Merced to name a few are convinced based on past state actions that Sacramento will ultimately look to this area to replenish the water that the tunnel would stop from flowing through the Delta.

The three rivers are the only other significant sources of water flowing into the Delta. South state and Bay Area demand already commandeers water from the Sacramento River basin. The Southern San Joaquin Valley — essentially points south of Modesto — uses so much water from the San Joaquin River basin that until 10 years the river ran dry every summer between the Mendota Pool and where the Merced River joins up with it. An agreement that reconfigured water use allowed the river to again have year round flow although at fairly low level.

The issue has to a large degree been dismissed as an issue for those pushing for the tunnel.

Endangering water supplies for the Northern San Joaquin Valley even further is a separate state action aimed at improving the number of Chinook salmon.

Sacramento concedes its plan may only increase the Chinook salmon numbers in the Stanislaus, Merced, and Tuolumne rivers by 1,103 while at the same time delivering devastating blows to the economies of San Joaquin, Stanislaus and Merced counties. The state’s own data says the tradeoff for 1,103 more fish could take 132,000 acres out of farm production, cause a $12.9 billion annual reoccurring loss to the three-county region, eliminate 4,000 jobs, and further imperial the groundwater by forcing cities and farms to pump 1.57 million acre feet — the equivalent of just over three-fifths of New Melones Reservoir when it is filled to the brim.

South San Joaquin Irrigation District and Oakdale Irrigation District would lose a minimum of 120,000 acre feet a year forcing cutbacks to farms and the cities of Manteca, Lathrop, and Tracy. In below normal rainfall years and especially in droughts, farms and the three cities would face serious water rationing. Based on hydrology and the state’s plan to increase unimpaired spring water flows in the Stanislaus to 40 percent the 2.4 million acre foot New Melones Reservoir will go completely dry 12 times every 95 years.

Altogether farms and cities depending upon the three rivers would lose 300,000 acre feet of water.

It is why SSJID and OID filed suit against the state plans in Tuolumne County Superior Court.  

There is also a serious salt water intrusion issue that already exists that water purveyors warn will worsen significantly once the tunnel is in place and water diversions start. High on the list of cities with water sources at risk are Tracy and Lathrop.

The SSJID switched to a closed system that allowed drip irrigation in Division 9 south of Manteca and west of Ripon almost a decade ago due to farmers who were forced to pump water from aquifers that were increasing in salinity as the years passed. When too much salt is placed on farmland via irrigation it renders the soil sterile in terms of it not being able to support much plant life or trees.

During 1989 when California was in a dry period, salt water was detected in agricultural and domestic well as far east as Jack Tone Road.

The Delta pivotal in

state water movements

Two thirds of California’s water originates in the Sierra while 50 percent of the state’s water supply flows through the Delta via the State Water Project.

The SWP supplies 29 million people with water and irrigates 750,000 acres of farmland.

The water that the tunnel would move provides 16 percent of the supplies need for the San Francisco Bay Area, 82 percent of the East Bay communities, 30 percent of Southern California, 25 percent of the Central Valley, 47 percent of the Central Coast, and 30 percent of Southern California’s Desert communities.

The DWR points to United States Geological Survey predictions there is a 72 percent chance of a 6.7 magnitude quake or greater in the next 25 years on major faults in the nearby Bay Area. There are also some minor faults in the Delta.

There are 1,000 miles of levees that could see some or most fail in the event of a major quake. Most are not in condition to withstand significant shaking, according to the DWR. The DWR doesn’t point out that many levees were built more than 120 years ago using materials adjacent to the rivers.

Levee failures could reduce water supplies between 6 to 12 months.

To contact Dennis Wyatt, email dwyatt@mantecabulletin.com