Next week people from around the globe will gather at the Global Climate Action Summit in San Francisco to explore solutions to climate change. California has long played a leadership role in reducing climate emissions. But the state has a crucial weakness in its climate readiness: its vast water system. Modernizing California’s “water grid”―the linked network of above- and below-ground storage and conveyance systems that connects most water use in the state―can help reduce the costs and impacts of a changing climate.

The PPIC Water Policy Center put together a team of experts in climate science, hydrology, ecology, engineering, economics, and law to review the weak points in California’s water system and recommend actions to build the system’s climate resilience. The focus of the work was on managing water scarcity, using lessons learned from California’s most recent drought.

We found that five climate pressures will seriously impact the state’s water system: warming temperatures, shrinking snowpack, shorter and more intense wet seasons, more volatile precipitation patterns, and rising seas.

During drought, California relies heavily on its water grid to manage supplies. This system will become even more important for managing more intense droughts of the future. Yet elements of this grid are in trouble, and climate pressures will make it harder to manage competing demands—particularly the need to store more water for drought while also capturing high flows to reduce flood risk, while also protecting freshwater ecosystems.

California’s climate is changing and drought intensity is increasing. Adapting to and preparing for change will require a more robust, better-integrated water grid. This should be a top priority for the next governor.

To make the grid climate-ready, the new administration should undertake a thorough assessment of weaknesses in the state’s storage and conveyance system—including important canals and aqueducts that help recharge groundwater, deliver surface water, and manage floods―and launch a major upgrade of this network.

The state’s many underground basins have a much large capacity for storage than surface reservoirs and will become much more important as a drought reserve. Strategic investments are needed to help California store water more effectively and take better advantage of opportunities to trade and share it—an important way to reduce the social, economic, and environmental costs of using less.

Adapting to a more volatile climate—including more intense winter storms—will also require more operational flexibility to enable storage and conveyance facilities to work together as an integrated water supply and flood management system. Investments will be needed to update hydrological assumptions for reservoirs, and improve water accounting in all sectors, including groundwater recharge and use.

This water infrastructure revolution won’t just be technically challenging: it will also require finding reliable funding to pay for necessary investments. Californians will need to look beyond general obligation bonds and develop long-term funding sources to adapt the water grid to a changing climate.

Strong leadership from state and local institutions has guided the development of the water system that California relies on today. Despite its many problems, this system has mostly served the state well, even in the face of occasional severe drought. Leadership—an essential ingredient for continued progress in water management—is a key requirement to prepare for droughts of the future.