Desalination and the future of water resilience in California

California has historically relied on a combination of surface water, groundwater, and imported supplies. However, these sources are becoming less dependable under prolonged drought conditions and climate stress.

The Colorado River, in particular, can no longer meet historic allocations, prompting a structural—not temporary—supply challenge. As pressure on shared sources intensifies, the state must identify supply options that are reliable, locally controlled, and resilient to climate variability.

Desalination as a climate-independent supply

Seawater desalination remains one of the few supply options that is largely independent of hydrological conditions. Community polling associated with active projects consistently shows strong public support, particularly where reliability and long-term resilience are clearly communicated.

From a policy perspective, desalination is increasingly understood as part of a balanced portfolio rather than a last resort solution.

A gap between public support and public discourse

While local surveys report majority support for desalination projects, public debate is often dominated by a smaller but highly visible opposition. Misconceptions around environmental impacts continue to influence decision-making, despite advances in technology and project design.

Bridging this disconnect requires sustained engagement, transparent data, and broader visibility of community perspectives.

Regulatory complexity is the primary constraint

Desalination technology is mature and proven. The more significant challenge lies in navigating California’s complex regulatory environment, particularly requirements associated with the California Ocean Plan.

Although senior state leadership has expressed support for seawater desalination, project delivery remains slowed by overlapping approvals, prescriptive standards, and site-specific interpretations.

Learning from large-scale delivery

The Carlsbad desalination plant demonstrates that large-scale seawater desalination can be permitted, delivered, and operated reliably over time. While smaller projects provide local benefit, system-level resilience will increasingly depend on assets capable of delivering meaningful volumes.

Carlsbad’s long-term performance has helped shift the conversation from feasibility to scalability.

New models of collaboration and water exchange

Emerging water exchange programs are expanding the role of desalination beyond coastal communities. By pairing desalination investments with regional or interstate agreements, agencies can reduce dependence on over‑allocated shared sources, such as the Colorado River, while improving reliability across multiple jurisdictions.

Projects such as the Doheny Ocean Desalination Project in Southern California show how coastal desalination can strengthen regional water systems, allowing inland agencies to benefit indirectly by freeing up imported water supplies, even without receiving desalinated water directly.

Innovation responding to environmental expectations

Environmental considerations are driving innovation in offshore and subsurface desalination concepts. Approaches that reduce nearshore intake and discharge impacts are drawing on offshore engineering experience from industries such as oil and gas.

While these models show promise, long-term operational performance and cost competitiveness will determine their role within future portfolios.

California’s water challenges are no longer episodic, they are structural. As shared systems reach their limits, locally resilient supplies become increasingly valuable.

Desalination’s role is evolving alongside new governance models, technological innovation, and regional collaboration. The question is no longer whether desalination belongs in the portfolio, but how it can be responsibly planned, permitted, and integrated at scale.

Progress will depend on:

• Aligning regulatory frameworks with long-term resilience objectives
• Continuing to advance environmentally responsive designs
• Expanding collaborative models that distribute benefits across regions
• Framing desalination within broader system performance and risk management strategies

As climate uncertainty grows, integrated planning and diversified supply will be central to delivering reliable water systems for communities across California.