TRUCKEE, Calif. – The Martis Valley Groundwater Basin stands as one of the region’s most valuable natural resources, providing mountain-filtered water to local communities. Recognizing its importance, the Truckee Donner Public Utility District (TDPUD) is moving forward with an update to the Martis Valley Groundwater Management Plan (GMP), ensuring the long-term sustainability and quality of this critical water supply.

During a recent discussion, Steven Poncelet, TDPUD’s public information and strategic affairs director, emphasized the significance of the Martis Valley Groundwater Basin, describing it as “an incredible natural resource” with substantial reserves and high water quality. “It’s large, it’s abundant, it’s very pristine, and mountain-filtered,” Poncelet said. The water requires minimal treatment, with only a small amount of chlorine added as required by law.

Despite its vast supply, Poncelet cautioned against complacency. “While we’re fortunate to have this abundant resource, it’s not infinite,” he said. “Water is precious, and everyone should only use the water that they need.”

To safeguard the basin’s future, TDPUD has collaborated with the Northstar Community Services District and Placer County Water Agency since 2013, implementing proactive groundwater sustainability efforts. The GMP, which undergoes a review every five years, provides a framework for responsible management and conservation. The local water agencies voluntarily opted to follow the current state public process and notification requirements, initiating a series of public hearings and stakeholder engagement before final adoption in June.

The Martis Valley Groundwater Basin is also subject to multiple layers of oversight, including California state regulations and the Truckee River Operating Agreement (TROA), a bi-state settlement governing water allocations from Lake Tahoe to Pyramid Lake. Initially categorized as a medium-priority groundwater source under the Sustainable Groundwater Management Act (SGMA), the basin was later reclassified as very low priority due to updated and accurate data.

TDPUD closely monitors groundwater levels, conducting monthly tracking and long-term studies to ensure sustainability. The district, along with its partners, evaluates sustainable yield—the amount of water that can be withdrawn without depleting the resource.

Monthly tracking involves measuring groundwater elevations at production and monitoring wells across the basin. This data helps assess the impacts of precipitation and pumping. A sustained decline in groundwater levels may indicate an unsustainable water supply, while basins that recover quickly after precipitation events are generally more sustainable.

“The Martis Valley Groundwater basin studies and monitoring have shown that the basin has been operated well within the sustainable yield. The studies have also shown that pumping has very small and short-term impacts to the basin and that groundwater levels are determined largely by precipitation,” Poncelet said. 

Poncelet estimates that the basin holds nearly 500,000 acre-feet of water, with an annual sustainable yield of 22,000 acre-feet. Current usage across all agencies, including private pumpers, stands at 7,000 acre-feet per year, with TDPUD accounting for approximately 4,500 acre-feet.

While Poncelet assured the public that the basin has ample supply, he reiterated the importance of conservation: “Just because it’s abundant doesn’t mean we shouldn’t care or do everything we can to manage it wisely,” he said. 

Water use in the region fluctuates significantly, with summer demand tripling due to irrigation. Poncelet pointed to new statewide regulations under California’s “Conservation as a Way of Life” initiative, which took effect in January 2025. These laws impose stricter limits on indoor and outdoor water use, as well as water loss from utility systems. 

As TDPUD moves forward with updating the GMP, it will continue engaging the public, promoting water conservation, and ensuring that the Martis Valley Groundwater Basin remains a reliable and sustainable water source for generations to come.