California’s climate is changing, and droughts are becoming more intense. Five climate pressures will seriously stress the state’s water system: warming temperatures; shrinking snowpack; shorter and more intense wet seasons; more volatile precipitation; and rising seas. While California is making good progress in addressing some areas of climate vulnerability, a more focused plan of action is needed.

Climate pressures will make future droughts more intense and affect the water system in the following ways:

• Higher temperatures reduce runoff by increasing evaporation. This is already contributing to declines in Colorado River flows and could affect other California water supplies in the future. It also creates challenges in providing cold water for salmon.
• Shrinking snowpack will affect California’s water supply, hydropower and flood control systems, which all depend on winter precipitation being stored as snow and a slow release of water in spring as snow melts. With more precipitation falling as rain and earlier runoff, “snow droughts” will have major effects on the management of surface reservoirs.
• Shorter and more intense wet seasons and more volatile precipitation – with wetter wet years and drier dry years – will make it harder to manage the state’s water system for competing needs.
• Rising seas increase the likelihood of saltwater intrusion in coastal aquifers and estuaries, including the Sacramento-San Joaquin Delta, and decrease freshwater supplies.

At the Public Policy Institute of California Water Policy Center, we assembled a team of 30 experts in climate science, hydrology, ecology, engineering, economics and law to review the weak points in the California water system and recommend actions to build its climate resilience. We focused on managing water scarcity because drought – more than any other aspect of California’s climate – will test the vulnerabilities of the state’s water supply system. Our findings use lessons learned from the unusually hot drought of 2012–16, which foreshadows the type of drought that will become more common with climate change.

During drought, California relies heavily on its vast “water grid” – the linked network of above- and below-ground storage and conveyance systems that connects most water use in the state – to manage supplies. Yet elements of this grid are in trouble, and climate pressures will make it harder to simultaneously store more water for drought while managing flood risk and protecting freshwater ecosystems.

Adapting to climate change requires 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 pursue the following initiatives.

First, all sectors must plan ahead for more intense droughts. Too often, state and local officials react to – rather than prepare for – drought. Advanced planning is particularly important for managing supplies for rural communities and the environment, which have the greatest drought vulnerability.

Second, undertake a thorough assessment of weaknesses in the state’s water grid – including dam safety in light of bigger storms – and launch a major, decades-long upgrade of this network.

In particular, increasing underground storage should be prioritized. The state’s many aquifers have a much larger capacity for storage than surface reservoirs and will become much more important as a drought reserve. Strategic investments in important canals and aqueducts that help recharge groundwater, deliver surface water and manage floods are needed to help California store water more effectively and take better advantage of opportunities to trade and share water. This is an important way to reduce the social, economic and environmental costs of using less.

Third, modernize our approach to storing and allocating water so that it can be managed more flexibly and in an integrated way. Twentieth-century approaches to water will not work in the warmer, more volatile climate of the 21st century. Outdated approaches to reservoir operations, water accounting, water rights and water for the environment will need to be adapted to new conditions. The goal should be to find equitable and efficient ways to allocate supplies among competing demands during dry times while promoting efforts to capture and store water during wet times.

Finally, we need to find reliable funding to pay for necessary investments. Most water spending in the state comes from local water bills and taxes. In keeping with that approach, water users will need to cover the bulk of investments to repair and upgrade the water grid. Californians will also need to look beyond reliance on general obligation bonds and develop long-term funding sources to become climate-ready. Funds from general obligation bonds should be used for projects that provide demonstrable public benefits, such as flood protection, restoration of groundwater basins, healthy ecosystems and help for disadvantaged communities.

Managing water will be at the forefront of climate change adaptation in California. By all measures, climate change is happening now, making action even more urgent. California has the know-how and financial capacity to prepare its water system for future droughts. But all the knowledge and money in the world will not work without leadership to build coalitions, craft compromises and make tough choices. Leadership at all levels will be the essential ingredient for success.

The views expressed in this article belong to the authors and do not necessarily reflect the editorial policy of Water Deeply.