Capturing water when it's available, saving it for when it's needed

Roseville’s water system draws from a mix of sources. Surface water is our primary supply, supported by a growing groundwater program and an expanding recycled water system. That strategic mix ensures reliable service. Over the past two decades, Roseville has invested in Aquifer Storage and Recovery (ASR), a method where water is injected into underground aquifers for storage and later use.

Since 2022, during periods of high water availability, the opportunity to store larger amounts of water has become even more apparent. While the City has long worked toward expanding groundwater recharge efforts, recent conditions have reinforced the value of being more intentional in how we use our system and water contracts to capture and store water when conditions allow, while still meeting the community’s daily water needs.

Making the most of available water

At its core, ASR is about timing. When surface water is available, especially during wet periods, Roseville can store more of it underground. When conditions turn dry, that water can be returned to the system. Think of it like a savings account. Water is set aside when available and used when needed.

This exhibit shows how Roseville stores water underground. When water is available, it is pumped into an underground aquifer for storage and later recovered for community use when needed.

In 2022, Roseville stored nearly 73 million gallons of water underground, enough to fill more than 110 Olympic-sized swimming pools. In 2023, that number grew to nearly 608 million gallons, enough to fill more than 920 Olympic-sized pools.

More recently, Roseville has expanded these efforts significantly. Through its Aquifer Storage and Recovery operations, the City has stored approximately 4,515 acre-feet of water underground, or nearly 1.5 billion gallons so far in 2026. That is enough water to meet the annual needs of about 9,000 homes, demonstrating how expanded ASR operations are strengthening long-term water supply reliability.

Expanding capacity, increasing opportunity

That shift is made possible by continued investment. Six wells are online today, two more are under construction, and additional wells are planned. The long-term goal is a system of up to 12 wells, capable of storing thousands of acre-feet of water each year.

An acre-foot is the amount of water needed to cover one acre of land one foot deep, or about 326,000 gallons.

More wells provide greater storage capacity and flexibility for water use. Recent state funding, including an $8 million grant, is helping accelerate this next phase and expand the City’s ability to manage water more effectively.

We have staff dedicated to managing our groundwater program. With six ASR wells online today, two under construction, and several more planned, groundwater is becoming an increasingly important part of Roseville’s long-term water reliability strategy.

“We’ve been building this system for years,” said George Hanson, Water Utility Manager. “Now that we have more wells, we can increase conjunctive use. When water is available, we can store it. When we need it, we can bring it back. That gives us a lot more flexibility than we’ve had in the past.”

Built on experience

This approach is grounded in experience. Water stored underground has already been used during dry periods to reduce reliance on Folsom Reservoir. It has also helped protect flows in the Lower American River during critical times. During wet periods, excess water can move quickly through reservoirs and downstream. With ASR, more of that water can now be captured and saved for later use.

What this means for you

What this means for you is simple.

• A more reliable water supply, even in dry years
• Less pressure on any single source
• Fewer sudden changes or restrictions

Your water system can make the most of available water and respond to changing conditions.

“This is about making sure water is there when people need it. We’re not waiting for a drought to figure things out,” Hanson added. “We’re planning ahead and putting ourselves in a better position no matter what kind of year we have.”

Ready for what comes next

Inside each well is a powerful pump, a maze of pipes, water quality monitoring equipment, and treatment systems working together to deliver reliable, high quality water to the community.

Water reliability is not about a single source or project. It is about how everything works together. By investing in ASR and expanding groundwater storage, Roseville is maximizing reliability by capturing water when available, saving it for dry periods, and ensuring a dependable supply for the community.

For more information about our water supply planning, visit Roseville.ca.gov/waterpromise.