Every five years the California Department of Water Resources releases an updated version of the California Water Plan— a comprehensive compilation of water data that guides future water policy in the state. The plan is commonly referred to as Bulletin 160.

Spurred by legislative mandate, the Water Plan serves as a guide for state and local officials as they pursue adequate water stewardship at a time of reduced allocations, drought and climate change.

Water Plan and Climate Change

The Water Plan describes potentially dramatic impacts to the state’s hydrology resulting from climate change. The Sierra Nevada snowpack — the primary source of the state’s water supply— could decrease as much as 40 percent by 2050, a storage volume of about 6 million acre-feet (an acre-foot of water is about 326,000 gallons). Rising temperatures, diminished snowpack, more extreme events and other conditions “will increase stress on the water systems in the future,” the plan says. “Because some level of climate change is inevitable, the water systems must be adaptable to change.”

Climate change adds complexities and questions regarding environmental impacts in the future. For example, rising water temperatures are attracting invasive species to waterways where they have not previously lived. This remains a key issue as state experts work to determine how to best incorporate a changing climate into water management planning, including flood planning due to sea level rise, peak flow changes and a reduced snowpack.

With the state’s population expected to keep growing, another key question is whether water supply will be able to meet demand. Urban growth is expected to make up the bulk of the projected gap between future supply and demand. Sunny, arid Southern California will account for half this growth, and this area faces decreased reliability of imported water from all its historic sources: the Colorado River, the eastern Sierra, and the Sacramento-San Joaquin Delta.

The 2013 Water Plan Update revolved around integrated water management and the need for a comprehensive and collaborative approach to achieve social, environmental, and economic objectives. The idea was to coordinate and consider all interests and possible benefits to water management across jurisdictional boundaries and on a geographic basis. Things like better flood management can help with ecosystem restoration and more reliable water supplies.

A preliminary draft of the 2018 Water Plan says the interconnected systems for using and managing water “are extremely complex and subject to continually changing natural and human-made conditions.” The plan describes many of the state’s ecosystems as “dysfunctional,” with much of the water supply and flood protection infrastructure “no longer functioning as intended or having exceeded their design life.” Without a plan of intervention, “our future prosperity will be vulnerable to the consequences of societal catastrophes, such as droughts, floods, environmental degradation, and species extinctions.”

The plan notes several key issues and challenges:

• The risk of “catastrophic flooding,” based on the fact that one in five Californians lives in a floodplain, and more than $580 billion in assets (crops, property and public infrastructure) are at risk.
• Ecosystems continue to decline, and several species are on the brink of extinction.
• Groundwater overdraft, lack of access to clean water in some communities and unreliable water supplies persist in some regions.
• Water management efforts typically focus on short-term actions without considering long-term desired outcomes.
• Climate change is having a profound impact on California’s water resources, such as changes in snowpack, sea level and river flows. The potential change in weather patterns will exacerbate flood risks and add additional challenges for water supply reliability.
• The state’s need to prioritize and fund long-term, sustainable investment in water management and ecosystem protection.

The plan says “just tweaking the current system” is not enough and that public policy “must move from stopgap measures to water resource strategies for future generations.”

The plan urges an alignment of planning and implementation efforts at the state, regional, local and tribal governance level “at effective geographic scales,” noting that factors such as the interdependent hydrologic, biological, economic and social processes and functions within each basin must be accounted for. Interactions among regions must also be considered “to encourage and increase mutual benefits within California’s interconnected water resource systems.”