What puts our water supply
at risk?

The Tri-Valley relies heavily on imported water through the California State Water Project, due to historic over pumping of the local groundwater basin. In the early 1960s, Zone 7 partnered with the State of California to receive imported water to help manage the local groundwater basin and provide critical drinking water supply. This impacts the cost of delivering our water, and leaves us vulnerable to long term reliability concerns. Our current system provides us with limited local control because so much of our water comes from outside the region.

Learn more about the obstacles and potential threats our water system faces.


Lake Oroville Dam

Aging Infrastructure

After working around the clock for more than 60 years, the State Water Project infrastructure is aging and at risk of failure. Investing in our infrastructure will ensure it can continue delivering water to over 25 million Californians. The State Water Project also provides jobs in construction, maintenance and operations of our water system. Doing nothing could prove to be just as costly as investing, given the Tri-Valley relies on this infrastructure for approximately 70% of our water. Investment also puts people to work, building a stronger economy and ensures our community will continue to thrive for generations to come.


California is no stranger to drought; it is a recurring feature of our climate. Defining drought is based on impacts to water users. California is an expansive state and impacts vary with location. The severity of droughts are based on the local or regional hydrologic conditions as well as the storage and conveyance infrastructure available to that area. Water supply conditions can vary greatly, even in regions that are in close proximity simply due to the complexity of our varying water infrastructure. This can often be confusing to residents who aren’t familiar with the systems that deliver the water to their household taps.

In the Tri-Valley, we rely heavily on water imported from the Delta through the State Water Project. It is common that during dry years, the water allocated to Zone 7 is severely reduced as there is limited water available. To buffer these limited allocations in dry years, we utilize a system of surface water reservoirs, our local groundwater basin as well as groundwater banking systems in Southern California. Because we have these resources, a single dry year isn’t a drought for Tri-Valley residents because our water infrastructure and groundwater resources mitigate the impacts. However, when multiple dry years occur together, those resources begin to get stretched to their limits.

Dry years can also mean that the imported water that we rely heavily on may be unavailable or can come at a high cost.



Earthquakes are a fact of life in California. According to the United States Geological Survey, there’s a 72% chance of a 6.7 or greater magnitude earthquake occurring in the Bay Area by 2043. This level of natural disaster could cause levees in the Delta to fail, potentially crippling the State Water Project’s ability to deliver fresh water.


Chance of a 6.7+ magnitude in the Bay Area by 2043


Climate Change

Climate change is impacting California’s water resources, as evidenced by changes in snowpack, sea level, and river flows. In California, we have seen average annual temperatures increase steadily since 1895 with the rate of warming accelerating since the mid-1970s. At the same time, freezing level elevations have risen by about 150 meters (500 feet) and winter chill time has decreased. Extreme heat events have also increased in duration and frequency. Spring snowmelt runoff has decreased, indicating warmer winter temperatures and more precipitation falling as rain rather than snow. Sea levels have also risen over the past century, threatening saltwater contamination of drinking water. As a result, our water resources are showing signs of stress.


Our watershed is a delicate balance of land-based and aquatic ecosystems made up of many tributaries along the way. Poor water quality anywhere in our watershed could impact drinking water, recreation opportunities, the manufacturing industry, agriculture, and the local and state economy. Most contaminants contributing to poor water quality are the result of current-use compounds from industrial, agricultural, urban, transportation, and natural sources. In addition, there is growing concern about new classes of contaminants, such as PFAS chemicals, pyrethroid pesticides, pharmaceuticals and personal care products. Both surface water and groundwater are vulnerable to different types of contaminants, which means different treatment methods and preventative measures are necessary. Learn more on Zone 7 Water Agency's website.

Delta at Risk

The Tri-Valley receives 70% of its raw water supply from the Sacramento-San Joaquin Delta, commonly known as the San Francisco Bay Delta or simply the Delta. There are federal and state efforts to help the Delta conveyance system be less vulnerable, which will have a direct impact on how the Tri-Valley receives water. Delta conveyance is threatened by various factors such as ecosystem considerations, seismic risk and sea level rise. Occasional droughts reduce water supply for agriculture and cities, contributing to difficult economic conditions. Homes, communities, farms, transportation corridors, and energy infrastructure are all vulnerable when our Delta is impacted. As sea levels continue to rise, the Delta will be faced with increasing saltwater intrusion, which threatens fresh water supplies flowing through the Delta.



Learn more about potential solutions to our various challenges