The Delta Tunnel — a $16 billion 45-mile long, 40-foot tall “straw” designed to siphon off water for Southern California urban areas before it enters the Delta — is winding down its environmental document comment period.

The tunnel would directly impact the water security of almost 2 million Northern  San Joaquin Valley residents, countless farmers and imperil Delta ecological systems.

Yet the Army Corps of Engineers continues to refuse to conduct even one in-person comment person.

The comment period ends next Tuesday, Feb. 14

Congressman Josh Harder has sent a letter to the Army Corps opposing the project and repeating his call for an in-person comment opportunity on the environmental documents.

“Sacramento has made it clear as day they don’t want to hear from our community when it comes to the Delta Tunnel water grab, but I refuse to let them off the hook,” Harder said. “Their failure to host a single in-person town hall on a project that will impact us for generations is inexcusable. Today, I’m sending them a letter from folks across San Joaquin County saying enough is enough. We will not let them take our water.”

The letter was sent after 150 people attending a water workshop Harder conducted in French Camp unanimously opposed the project.

The biggest issue for the Northern San Joaquin Valley region is the fact 85 percent of the water that flows through the Delta comes from the Sacramento River watershed.

The plan is to divert a good share of that water under the eastern edge of the Delta to send it to the forebay of the  California Aqueduct near Mountain House northeast of Tracy.

That water is now helping keep salt water intrusion into the Delta at a minimum. As such it is protecting fragile ecological system that support endangered fish.

Even proponents of the tunnel concede the only way to replace that water flow from the Sacramento River into the Delta is to take water from the San Joaquin River watershed.

That means it will almost certainly be taken from  the Stanislaus, Merced and Tuolumne watersheds that feed the San Joaquin River.

 The potential for the tunnel project to devastate the Northern San Joaquin Valley as the Los Angeles Water & Power Department’s grab of Owens Valley water did a century ago is underscored by a state study five years ago conducted to justify proposed higher fish flows.

The state Department of Water Resources concluded in 2018 that increasing the unimpaired water flows on the three rivers by 300,000 acre feet of water a year might yield 1,103 more fish overall on an annual basis.

The same research said those 1,103 additional fish would force 130,000 acres of croplands and orchards to go fallow. It would cost 4,000 jobs in San Joaquin, Stanislaus, and Merced counties with and overall regional economic loss of $12.9 billion.

To give you an idea of how much water 300,000 acre feet represents, take a drive to New Melones Reservoir. There was 1,018,512 acre feet of water as of Tuesday in the reservoir designed to hold 2.4 million acre feet.

It’s about a 30 percent of what you will see, right?  Not exactly. It doesn’t include  “dead storage.”

Dead storage is water in a reservoir that can never be released to send downstream as it is below the outlets. New Melones has somewhere around 300,000 acre feet of dead storage.

After taking out 300,000 acre feet for increased flows for Chinook salmon at specific times of the year and 300,000 acre feet for dead storage, that means as of today there would be only 400,000 acre feet to provide drinking water, crop irrigation, and other urban uses.

That means the state would make existing drought conditions even worse by fiat.

The tunnel, however, once it starts diverting water would require even more water to protect the Delta at the current level compared to the 300,000 acre feet the state wants form the San Joaquin River watershed to increase current fresh water flows.

The environmental document for the tunnel project released last month concedes it will have negative impacts not only on the Delta’s ecological system but also the economic of San Joaquin County and adjoining jurisdiction.

San Joaquin County has the largest area within the Delta out of six counties involved.

It has a wealth of productive agricultural land in the Delta.

The Stanislaus River provides water for 220,000 residents in Manteca, Tracy and Lathrop plus provides irrigation water for 50,000 acres of farmland in the Manteca, Ripon, and Escalon areas.

By bypassing the Delta, the Metropolitan Water District — the largest water purveyor in the south state — would have “cleaner” and more “secure” water.

That’s because Sacramento River water wouldn’t flow through the Delta. That means salinity levels are likely to rise in the Delta given there would be less fresh water to push back on water from the San Francisco Bay.

The need to backfill water diverted into a tunnel has the potential to be disastrous for the Delta ecological system and could pose serious issues for endangered species such as the Chinook salmon and Delta smelt.

Protecting the fish is why the state would ultimately be forced to replace the water. That’s because even though vast amounts of water have been diverted south since the California Aqueduct was built more than 60 years ago, the water before it headed south continued to flow through — and benefit — the Delta ecological system.

Los Angeles water interests argue their water supply would be more secure in the event of an earthquake collapsing levees in the Delta.

At the same time, however, it would mean a mechanism would be in place where water earmarked for Los Angeles could bypass the Delta in times of drought creating domino impacts on farming, fish, the environment, and even recreation.

Harder along with fellow Congressman John Garamendi are pushing an amendment to prohibit the Army Corps of Engineers from issuing a Clean Water Act permit for the California Delta Conveyance Project

To contact Dennis Wyatt, email dwyatt@mantecabulletin.com