December 9, 2016

Delta-tunnel proposal raises huge environmental questions

General aerial photo of Delta patterns, July 15, 2004. Photo by Paul J. Hames.

General aerial photo of Delta patterns, July 15, 2004. Photo by Paul J. Hames.

On July 25 Gov. Jerry Brown announced plans to build a massive twin-tunnel system to carry water from the Sacramento-San Joaquin River Delta to urban users in Southern California and agribusinesses on the west side of the San Joaquin Valley. The two huge underground tunnels would carry Sacramento River water 37 miles to the federal and state pumps at Tracy.

Key decisions, however, on how much water will ultimately be diverted, how the system will be operated, and what actions will be taken to protect the region’s endangered species will be delayed until after construction has begun.

Sierra Club California senior advocate Jim Metropulos says, “Californians need to know upfront how much water will be taken from the Delta by the massive tunnels, and how that will impact fish and wildlife and how any negative impacts will be mitigated or avoided. Right now, the science shows that some species, including the winter Chinook salmon, would be harmed by the construction of the tunnels. The project could make things worse for fish and wildlife than not doing anything at all.

“The governor’s proposal also fails to show how the state will comply with the legal requirements that California reduce its reliance on water from the Delta.

“California water agencies can increase water supplies in less expensive and faster ways by expanding water conservation, water recycling, and stormwater recapture, and by repairing and revamping older local water-delivery systems.”

All signs seem to suggest that the state intends to allow the construction of world-record sized tunnels or pipes capable of diverting 15,000 cubic feet per second from the Sacramento River–nearly all of its average freshwater flow. Diversion of such a large quantity of water would have devastating impacts to fish and wildlife and water quality in the Delta. Estimates of the project’s costs are anywhere from $20 – $50 billion.

While the state is preparing to move forward with this project, many details remain unavailable to the public about it. Before California gives the green light to build a peripheral canal or tunnels around the Delta to divert water, Sierra Club California believes that some basic questions should be fully answered so Californians have all the facts about what’s being proposed.

  • How much will the project really cost? We’re being told that the costs of just the record-sized tunnels project are estimated to be at least $12 billion, but this does not include operation and maintenance, which ups the cost to $17 billion. Add in financing, and the costs reach $51 billion according to Bay-Delta Conservation Plan documents. Gov. Brown estimates the costs at $14 billion.
  • Who pays for the project? And who pays for the project’s impacts? The state last week released a “Benefit Analysis of the BDCP” that suggests the project makes economic sense for the South of the Delta water contractors, but only if huge costs are shifted to others, and if benefits not part of the project are counted. Why has no true statewide cost-benefit analysis been prepared or planned for this massive public-works project?
  • How much “new” water will be produced annually after the project is completed? What is the source? What are the real export levels and how were they determined?
  • When will this “new” water be available–2020? 2030? 2050?
  • How will this “new” water be divided among different users and the needs of the environment? How and when will that be determined?
  • What are the upstream impacts of this project on flows, temperatures, fisheries protection and reservoir operations?
  • Scientists report that climate disruption will impact California–its coastline, sea level, weather patterns, precipitation rates and a growing list of other conditions. The current proposed plan indicates climate assumptions will be “forthcoming”. How will the proposed project and its operations be adaptable to changes in California’s climate?

These fundamental questions need to be fully answered before the state spends another dime on the multi-year, multi-million dollar BDCP process. Too much is at stake for the Delta for the state and federal agencies to announce a plan that defers important decisions while an expensive and potentially damaging water-diversion project is allowed to proceed.


  1. Wayne Baird says:

    For $25-billion we could EASILY build multiple desalinization plants all along the coast. This would use ZERO water from the Delta, and would be able to supply Southern Cal and the central valley with all the water they will ever need. Water politics is bad politics. Desalinization of our most abundant resource puts an end to this water nonsense.

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