Current Campaign: the twin tunnels

Stop Governor Brown’s misguided solution to California’s water issues.


The Twin Tunnels are a proposal by California Governor Jerry Brown to build a gigantic water conveyance system under the Sacramento/San Joaquin Delta to Southern California. The project would consist of two tunnels, each 20 to 40 feet in diameter and 35 miles long, buried 150 feet beneath the heart of the Delta.

The Twin Tunnels would be ruinously expensive to ratepayers and profoundly destructive to Delta ecosystems.

The ultimate purpose of the Twin Tunnels is diversion of Sacramento River water around the Bay/Delta estuary for distribution to San Joaquin Valley agribusiness and Southern California cities and suburbs. Ultimate costs could range above $69 billion. State officials are attempting to implement the project without voter approval.

The tunnels are embedded in a “restoration” scheme called the Bay Delta Conservation Plan (BDCP). While the BDCP promotes the project as a “conservation measure,” the only real beneficiaries are state and federal water contractors who consider their water supplies insufficient or unreliable. In short, the habitat restoration component of the BDCP is nothing more than a greenwash of a project that will destroy the Delta.

Further, if the Twin Tunnels fail to deliver water at a reasonable cost, the shaky financing arrangements for the project threaten a massive tax bill for ratepayers, taxpayers and water agencies. This would place a huge fiscal burden on the State of California, and their approval would be tantamount to fiduciary malfeasance. In the event of utility agency defaults, property owners in the affected areas and the state treasury will be required to repay the bonds.


While Twin Tunnels proponents claim the project will benefit endangered and threatened fish, their arguments are undermined by the special 50-year “no surprises” take permit embedded in the authorizing documents. This will allow the killing of species listed under the U.S. Endangered Species Act for the project’s first five decades of operation.

Further, the Twin Tunnels likely will require a suspension of the California Clean Water Act and the California Water Code because it will degrade Delta water quality in blatant violation of these existing state regulations. In light of Governor Brown’s statement that he “…never met an exemption from the California Environmental Quality Act that (he) didn’t like,” it is highly likely that the administration will seek exemptions from several environmental laws for the Twin Tunnels.

By any objective analysis, the Twin Tunnels pose a dire threat to the Delta’s fisheries. The project would shunt  high quality Sacramento River water under the Delta to the south, leaving the estuary with disproportionate flows of heavily polluted water from the San Joaquin River. These reduced flows and higher contaminant levels of pesticides, herbicides, arsenic, selenium and boron bode ill for the salmon, steelhead and numerous other species important to our commercial and recreational fisheries. The San Joaquin is already designated as an “impaired water body” by the State Water Resources Control Board and the U.S. Environmental Protection Agency; the Twin Tunnels will only make this already bad situation worse.

Reducing flows from the Sacramento River will also allow saltwater from San Francisco Bay to intrude eastward through the Delta. Increased salinity in Delta water will have profound and negative impacts on Delta agriculture and further degrade critical habitat for such imperiled species as salmon, steelhead and Delta smelt.

Twin Tunnels advocates claim adverse impacts on fish will be mitigated by restoring 100,000 acres of habitat in the Delta. These projects, they maintain, would result in seasonally inundated floodplains, subtidal and intertidal freshwater and brackish wetlands, and shallow-water channel margin habitat. They are intended to increase food production for native food webs and fish. But in the absence of additional fresh water, scientists are skeptical that these habitat projects will work as advertised by the BDCP. The State Water Resources Control Board has already stated that habitat restoration and increased flows are both necessary to the recovery of the Delta’s fish populations.

Beyond the likelihood of increasingly polluted inflows to the Delta due to the Twin Tunnels, the BDCP’s habitat “improvements” may ultimately degrade rather than enhance the environment: the National Research Council, an arm of the National Academy of Sciences, has warned that such restorations may mobilize mercury from historic gold mining activity, transferring it from the deep sediments where it is now safely buried into the aquatic food web.

In short, the much-touted environmental “benefits” of the Bay Delta Conservation Plan are at best overestimated, and at worst, specious.



The negative fiscal impact of the Twin Tunnels matches the project’s dire environmental consequences. Cost estimates for the scheme range from $20 billion to $69 billion—but given the history of cost overruns for public works projects of this scope, the final price tag likely will be higher.

The Twin Tunnels would be built by the California Department of Water Resources (DWR) – an agency with an especially egregious record of project cost inflation. In the 1990s, DWR oversaw the construction of the Coastal Branch Aqueduct, a subsidiary canal to the State Water Project designed to improve the water security of Santa Barbara and surrounding environs. DWR estimated the Coastal Branch’s cost at $270 million, a price that seemed reasonable to Central Coast voters, who approved the project in 1991. But construction costs alone were $595 million. With the requisite expense of debt service, expenditures will reach $1.76 billion by 2035. Further, DWR promised that the Coastal Branch would assure 97 percent reliability in water deliveries to Santa Barbara. Instead, water deliveries to the Central Coast have stood at 36 percent of contracted amounts since the completion of the project.

DWR’s history of inaccurate cost and reliability assessment is deeply troubling, especially as pressure to construct the Twin Tunnels increases. No details have been released identifying who is going to pay the billions of dollars needed for the project.

Finally, no plan has been drafted revealing just where the water will be found to fill the Twin Tunnels. There’s a simple reason for this: it doesn’t exist. California’s finite water resources are dramatically oversubscribed, and a new water conveyance system, no matter how extravagant, can’t change this stark fact. All reliable computer models indicate the situation will only worsen with ongoing climate change: in the future, California is likely to have even less exportable water than it has now.


Twin Tunnels proponents claim the project is necessary to insure against catastrophic Delta levee failure. A large seismic event along the Hayward Fault, they claim, could collapse levees and threaten the infrastructure that delivers water to millions of southern Californians. They note this danger is exacerbated by seas that are rising inexorably from climate change.

These threats, however, have been overblown and have been extensively refuted by Delta levee engineer Robert Pyke.  The fact is that the existing levees in the Delta could be sufficiently strengthened to ensure protection of water export systems – and at a cost of $2 billion to $4 billion, much less than the lowest estimate for the Twin Tunnels. Levee strengthening must proceed in any event to protect Delta communities, Delta infrastructure, and the region’s $5 billion agricultural industry.

The Twin Tunnels are merely a conveyance system – they will do little to increase water supplies or improve water delivery reliability. However, we can accomplish both ends through a combination of cost-effective local initiatives, including recycling, conservation, stormwater capture, levee strengthening, and brackish groundwater desalination.


From the environmental, fiscal and public trust perspectives, the Twin Tunnels are a losing proposition.  Despite claims to the contrary, they would devastate Delta fisheries and wildlife. Exemptions to existing state regulations would be needed for their construction and operation, undercutting the nation’s most effective and comprehensive canon of environmental law. The project’s price tag is also prohibitive—up to $70 billion, threatening to bankrupt local water agencies that would be responsible for construction costs, management and upkeep costs, and bonded debt.

Finally, proponents ignore a bedrock reality that obviates the need for a water conveyance project of this scope:  there is not enough water in California to justify construction. And under any likely climate change scenarios, there will be less water available for export in California, not more. We should not spend precious public dollars on white elephants that plunder the environment and the pockets of ratepayers for the benefit of the few and powerful. Rather, we must invest wisely and well in creating a resilient water distribution system based on recycling, conservation and the development of local supplies.


Planned location of the Twin Tunnels The tunnels will divert watershed source water from the Sacramento River, bypassing the California Delta to state aqueducts and onward to the San Joaquin Valley.