Groundwater Recharge Archives - Sonoma County Groundwater Sustainability Agencies

Martha Way Well Aquifer Storage and Recovery Pilot Test

The Santa Rosa Plain Groundwater Sustainability Agency (GSA), in partnership with the City of Santa Rosa Water Department (Santa Rosa Water), will conduct a pilot test at an existing well on Martha Way to evaluate the feasibility of storing and recovering drinking water in the underground aquifer. This process is known as Aquifer Storage and Recovery (ASR), which you can learn more about here. The purpose of the project is to gather valuable information about the viability of ASR as a tool to sustainably manage our local water supply—especially during droughts, emergencies, or peak demand periods. The project consists of temporarily adding ASR capabilities to the existing well to recharge water from Santa Rosa Water’s drinking water supply into the underground aquifer system. Approximately 2.26 million gallons of drinking water were recharged into the aquifer and stored, and 2.52 million gallons were recovered via the Martha Way well.

Project Location

This pilot test was conducted at the Martha Way well, near the intersection of Martha Way and Albert Drive and adjacent to the Santa Rosa Southeast Greenway.

Project Timeline

Construction is anticipated to start in the second or third week of July and be completed in October 2025. Daily work hours will be weekdays 8am-6pm and only on weekends if necessary with advanced notice.

Mid July 2025: Equipment Installation –The pump, generator, piping, fencing, and monitoring systems were installed.
September 2025: ASR pilot began.
September – December 2025: Testing Phase – Three ASR cycles completed while collecting groundwater and water quality monitoring data.
December 2025 – May 2026: Data analysis and final reporting.

Project Results

Three ASR test cycles were conducted, each involving water injection (recharge), a storage period, and water recovery. Each cycle increased in duration, with the final cycle including 11 days of recharge and 5 days of recovery. The depth to groundwater was approximately 34 feet below ground surface prior to the ASR pilot test, and pilot operations helped raise groundwater levels to 26 feet below ground surface.

During the pilot, the overall water quality characteristics at the Martha Way Well changed as expected. Stored water was a mixture of native groundwater which is high in iron and manganese, and the added drinking water which had low or absent levels of iron and manganese. Iron and manganese concentrations were lower in recovered water than native groundwater conditions but were still close to the secondary maximum contaminant loads.

Results show that ASR at the Martha Way well is hydraulically feasible, but the consultant team recommends additional construction and testing to ensure it can meet local needs in the future.

Read the full technical report here.

Project Funding

The ASR pilot test is funded through a grant issued from the California Department of Water Resources (DWR). Results from the pilot test will inform the Santa Rosa Plain GSA and the City of Santa Rosa in considering ASR and regional water banking opportunities.

Contact Us

If you have any questions about the project, please contact: City of Santa Rosa Project Manager: Claire Nordlie, 707-543-3962, cnordlie@srcity.org GSA Project Manager: Indigo Bannister, 707-304-7313, ibannister@westyost.com

Cartoon of two wells - 1 well that shows water being both pumped into the aquifer and 1 well being pumped out from the aquifer

ASR Planning

Stormwater Recharge Planning

Sonoma County’s weather is characterized by rainy winters, followed by long, dry summers. During large winter storms, creeks and streams are often overwhelmed and can cause flooding in local communities. In contrast, dry summers—and increasingly frequent droughts— can place strain on both surface water and groundwater supplies. This Mediterranean pattern is becoming increasingly pronounced as our climate changes, but it also provides an opportunity.

Across California, water managers are rethinking how we handle stormwater. Instead of viewing it solely as a flood risk, we are beginning to see stormwater as a valuable resource that can help replenish our groundwater basins and improve long-term water reliability. By slowing, spreading, and sinking stormwater into the ground through recharge basins, open spaces, and natural waterways, we can use high-flow events to increase groundwater levels within the aquifer, enhance baseflows to interconnected surface water, and help support sensitive beneficial users.

With SGMA Implementation grant funds, the Petaluma Valley GSA has taken steps to build on stormwater recharge projects identified in the Southern Sonoma County Stormwater Resources Plan and further planning toward broader implementation of Stormwater Capture and Recharge projects.

In 2024 and 2025, the GSA and a consultant team led by Bachand & Associates began planning for three pilot projects on sites yet to be determined:

Stream Restoration to Reconnect Streams to Shallow Groundwater: Pilot will construct beaver dam analogs (essentially human made beaver dams) in a stream to slow flows and widen stream area, increase stream to aquifer connectivity, and reduce losses from shallow aquifer to surface water.
Upland Vineyard Cover Cropping and Compost Applications to Increase Groundwater Storage: Pilot will study best management practices for vineyards to increase groundwater storage, such as using a crop cover mix that will have elevated groundwater benefits and high-rate compost application.
Upland Swales on Contours to Increase Groundwater Storage on Upland Pasture and Rangeland: Pilot will construct swales (shallow depressions) on slopes in pastures to slow water as it travels downhill.

Stormwater recharge is an integrated and voluntary resource management strategy that takes collaboration with landowners, farmers, scientists, and water managers to create a successful project. The pilot projects are designed to answer practical questions such as: How quickly does water soak into the ground, and what factors — like soil type and cover crops — affect that rate? The pilots hope to lay the groundwork for future projects by figuring out what it takes to run programs like these, from working with willing landowners to managing the day-to-day logistics.

Staff will use what they’ve learned from these pilots to estimate the costs and potential benefits of expanding on-farm and other stormwater recharge to a larger scale. This is an important step toward building a more resilient local water supply.

Read more about the pilot plans and ongoing efforts here.

Aquifer System Recovery Planning in Santa Rosa Plain

Stormwater Recharge Planning in Santa Rosa Plain

Stormwater has been getting a lot more attention in recent years. With record-breaking winter storms and a renewed focus on treating our groundwater aquifers as ‘underground reservoirs’, now is the perfect time to combine these water forces through Stormwater Recharge.

With SGM Implementation grant funds, the Santa Rosa Plain GSA has just kicked off our pilot project for Stormwater Capture and Recharge Planning.

The project is looking to diversify and advance our groundwater supply by developing two pilot projects that will capture stormwater runoff during rain events and recharge the water into the aquifer. This project will provide multiple benefits including locally increasing groundwater levels within the aquifer, enhance baseflows to interconnected surface water and help support sensitive beneficial users.

This task will include site-specific investigations, modeling, and pilot studies of both on-farm recharge and upland recharge as well as other ways to ‘spread and sink’ stormwater into the ground. Stormwater recharge projects have been identified in the Russian River Regional Storm Water Resource Plan, and include the following project types:

recharging onsite runoff, such as on-farm recharge of local runoff, and
recharging unallocated storm flows, which require temporary diversions and conveyance of flows from streams to recharge locations.

In order to increase the amount of water we put into the ground, the GSA is working with a team of scientists and engineers to consider the following factors for recharging stormwater:

Water available for recharge, including any water rights considerations and permitting needs,
Areas with permeable near-surface soils and sufficient depth to the aquifer,
Outreach to interested landowners with locations that could help sustain dry-month baseflows to streams and support groundwater dependent ecosystems

Stormwater recharge is an integrated and voluntary resource management strategy that takes collaboration with landowners, farmers, scientists, and water managers to create a successful project. These pilot projects will show what is possible for local stormwater recharge and hopefully lay the groundwork for future recharge projects.