Urgent Groundwater Action Needed in Sonoma Valley: New Priority Areas Identified

The Sonoma Valley Groundwater Sustainability Agency (GSA) has designated two new Groundwater Sustainability Priority Areas—El Verano and Eastside—in response to critical groundwater declines threatening long-term water reliability for homes, farms, and businesses in the region.

Despite 20 years of voluntary conservation efforts, groundwater is being extracted faster than it can naturally replenish. In the most severely impacted zones, levels in deep aquifers (greater than 200 feet) are dropping by up to eight feet per year, with some areas losing nearly 100 feet in just the last decade.

Understanding the Causes

The primary cause is over-pumping of deep aquifers, which recharge very slowly compared to the shallow aquifer. This imbalance is further intensified by:
• Low-permeability geological formations that hinder natural recharge.
• The Eastside Fault, which may act as a barrier to groundwater flow.
• The growing impacts of climate change, including more frequent droughts and fewer, more intense storms that reduce effective groundwater recharge.

“Groundwater declines are a serious and growing problem,” said Marcus Trotta, Principal Hydrogeologist at Sonoma Water and Plan Manager for the GSA. “It’s a decades-in-the-making issue that no single solution or agency can fix alone. We need everyone’s help.” The most immediate significant impact of declining groundwater levels is loss of capacity on shallower wells in these areas. Additionally, if continued, other impacts such as seawater intrusion, land subsidence, or direct effects to ecosystems may occur in the future.

Community Meeting Held on May 1

A public meeting was held on May 1 in Sonoma Valley, giving residents an opportunity to learn about the current challenges, review data, and ask questions about potential solutions. The meeting included a Resource Workshop with many local organizations offering information on how individual well owners can help address the groundwater situation. A recording of the meeting presentation is available online.

Sonoma County District 1 Supervisor and Sonoma Valley GSA Board of Directors Vice-Chair Rebecca Hermosillo emphasized the importance of community collaboration: “The May 1 meeting was an important step for our community to gather and learn about the groundwater challenges we’re facing. We must all work together to take action and protect our water supply for the future.”

Steps Toward a Sustainable Future

The GSA is actively pursuing a range of voluntary and potential future mandatory solutions, including:
• Recycled water pipelines to reduce irrigation demand on groundwater.
• Voluntary well metering programs like Flow Smart to help users track and manage usage.
• Water conservation incentives through programs like Well Aware.
• Long-term recharge projects, such as Aquifer Storage and Recovery (ASR) and seasonal stormwater capture.
• Potential policy tools under consideration including updated well permitting, mandatory metering (excluding typical rural residential users), and groundwater trading systems.

Residents, farmers, and businesses are encouraged to:
• Join the Level Up! program to help monitor their own well groundwater levels.
• Apply for a free Flow Smart meter, valued at $4,500–$6,000. (a limited number still available)
• Leverage resources, tools and strategies provided through the Well Aware program
• Stay engaged with GSA events and decisions.

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