Risk and Reward: Why California Governors Continue to Push for the Delta Tunnel

By Max Gomberg,  Senior Policy Advisor,  California Water Impact Network
This piece was published in Maven’s Notebook, June 5, 2025

In its latest propaganda campaign promoting the $20 billion plus Delta Conveyance Project (DCP), the Newsom administration is claiming risk to future water supply as a major justification. The foremost cited risks relate to climate change-driven impacts: loss of snowpack, extreme droughts, and sea level rise.

A new study commissioned by water contractors who would benefit from the DCP finds that these impacts, combined with the implementation of laws and regulations to protect the environment, will cause water shortages in Southern California and billions of dollars in economic losses in both the urban and agricultural sectors. It sounds like a dire situation that requires a major governmental intervention – like a gigantic tunnel.

Because powerful and wealthy industries support the DCP, it’s easy to understand the political calculus that drives Governors to push for it: as always in California, water flows toward money. Moreover, it is the type of project that is immensely gratifying to the stereotypical male ego. It is a legacy project: massive, long-lasting, and a testament to power. It is a literal monument to any politician who is heir to a family dynasty or aspires to be President.

Yet underlying the greed and relentless political ambition lies the question of risk – true risk, that is. How much is there? To whom does it apply? And what are the alternative options for mitigating future water supply reductions?

Let’s start with the level of risk. Climate change is already reducing water supply. It will continue and accelerate in the decades ahead. Additionally, there is always the chance of a megadrought; a periodic occurrence over the past few thousand years. Under current conditions, agriculture and large commercial interests are winners over the environment and the tribes, communities, and industries (e.g., fishing & recreation) that rely on healthy rivers. Less water and more severe droughts require new decisions about who takes the hit and how the government handles the consequences.

However, the Newsom administration’s environmental analysis found that without the DCP, water supplies for Southern California will decline by nine percent over the next several decades.[1] The same analysis determined that the coastal zone cities from Los Angeles to San Diego would not face shortages due to conservation and investments in local supplies.[2] Thus, the magnitude of risk for SoCal urban populations is vastly overstated.

Nevertheless, the Southern California risk portfolio includes diminishing flows from the Colorado River. The Colorado River’s flow is divided among seven states, more than two dozen tribes, and Mexico; it is severely over-subscribed, and faces even greater reductions from climate change impacts across the Southwest. Although its water is used for major metropolises such as Phoenix and Las Vegas, the lion’s share is used to irrigate crops such as alfalfa (i.e., hay) in the desert. Some of that alfalfa is then exported to the Middle East and China.[3]

In California, large and powerful agricultural water districts control the most senior water rights to both the Sacramento-San Joaquin River system and the Colorado River. The Palo Verde and Imperial Irrigation Districts have rights to more than 3 million acre-feet of Colorado River Water[4], and the Sacramento River settlement contractors and the San Joquin River exchange contractors control nearly 3 million acre-feet of water from their respective river systems[5]. These allocations alone dwarf the average of 1.39 million acre-feet[6] that flows to Southern California through the State Water Project.

When tunnel proponents discuss risk analysis, they make one fundamental assumption: agricultural water cannot be appropriated for urban uses. In other words, they cannot envision a scenario wherein agricultural water users are compelled or compensated to temporarily or permanently transfer some of their water allocations to urban areas.

Thus, the only alternatives to the tunnel are local supply sources (e.g., recycled water) and reductions in total deliveries – alternatives they claim are both too costly and represent a net decrease from current supply levels. By minimizing impacts to the environment, tribes, and Delta communities, they then reach the ill-founded conclusion that the tunnel is the only cost-effective way to mitigate the future supply risk.

Claiming that major urban areas may face water scarcity is a good way to stoke fear and build support for the tunnel. But the risk of water scarcity only exists if urban areas bear the brunt of reduced water deliveries and cannot access a share of the water allocated to agriculture. And here lies the heart of the matter: The agricultural dynasties that have made fortunes based on access to water from the Sacramento-San Joaquin and Colorado Rivers are not going to give up that water without a fight. But with climate change impacting California’s water supply, it’s a fight we must have. It is time to assess water supply risk based on the needs of our cities and the environment instead of cattle feed and nuts for export.

The 27 million people served by the State Water Project don’t need a massive and outrageously expensive tunnel, and they should not assume unnecessary costs created by a diminishing water supply.

[1] Delta Conveyance Project Final Environmental Impact Report, 6-38.

[2] Ibid., 6-47.

[3] See https://www.latimes.com/environment/story/2024-03-28/alfalfa-hay-beef-water-colorado-river, accessed June 3, 2025.

[4] See https://www.usbr.gov/lc/region/g4000/contracts/entitlements/Entitlements_State_of_CA.pdf, accessed June 3, 2025.

[5] See https://www.usbr.gov/mp/cvp-water/docs/cvp-water-quantities-for-delivery-2023.pdf, accessed June 3, 2025.

[6] Southern California receives 63% of the State Water Project deliveries. See page 13 of DWR’s Bulletin 132: https://water.ca.gov/-/media/DWR-Website/Web-Pages/Programs/State-Water-Project/Management/Bulletin-132/Bulletin-132/Files/Bulletin-132-21-073024.pdf, accessed June 3, 2025. According to DWR’s 2023 Delivery Capability Report, State Water Project long-term average deliveries are 53% of total contract allocations, or 2.20 million acre-feet. See page 7.70 here: https://data.cnra.ca.gov/dataset/finaldcr2023/resource/92356681-957a-48ee-97c4-529d25b9dbb2?view_id=2c4f5269-b709-43ad-b60c-e182fcbaa47e, accessed June 3, 2025. 2.20 x 0.53 equals 1.39.

C-WINJune 30, 2025