Madison, WI – March 2026 – The Yahara WINS Watershed Carbon Project, developed by Virridy and led by the Madison Metropolitan Sewerage District (the District), has successfully been issued its first set of verified carbon credits—24,143 in total—under a new, science-based methodology for avoiding emissions from water infrastructure. The credits were issued by Regen Registry on January 16, 2026, following third-party verification by Sustainability Science.

These credits are the first issued under Regen Registry's new Credit Class, “Nature-Based Watershed & Green Infrastructure Solutions to Avoid Gray Infrastructure Emissions,” using the “Nature-Based and Green Infrastructure Activities Avoiding Emission from Water Management Gray Infrastructure Construction and Operations Methodology v1.0.” The methodology enables utilities to quantify and verify greenhouse gas (GHG) emission reductions from watershed-based alternatives to conventional infrastructure.

The project is a landmark demonstration of how climate finance can support water quality compliance and ecological restoration while avoiding energy- and chemical-intensive infrastructure upgrades.

Watershed Compliance Meets Climate Action

Rather than constructing a conventional tertiary treatment system at its Nine Springs Wastewater Treatment Plant—requiring substantial electricity and chemical inputs—the District implemented a watershed-scale solution approved as a fully permitted Adaptive Management program under the Wisconsin Department of Natural Resources and the U.S. EPA through the Clean Water Act.

Launched in 2017, the Yahara WINS program unites municipalities, counties, conservation organizations, and farmers to implement field-level Best Management Practices (BMPs) that reduce phosphorus runoff and improve water quality. These include cover crops, nutrient management, low-disturbance tillage, streambank stabilization, wetland restoration, and more. The project spans 139,000 hectares across Dane, Columbia, and Rock Counties.

The results: improved aquatic habitat, reduced algal blooms, better flood resilience, and—now verified—avoided carbon emissions.

“When we launched Yahara WINS, we believed that investing in watershed health could deliver real, measurable outcomes—not just for water quality, but for our community and environment. It’s incredibly rewarding to now see that work validated through the issuance of carbon credits,” said Martye Griffin, Ecosystem Services Manager at the District. “Carbon finance has finally reached a point where it can meaningfully reduce the cost burden on ratepayers while supporting long-term ecological benefits. This milestone shows that local action can drive notable global impact.”

Using life cycle assessment (ISO 14040/14044), Virridy quantified the emissions avoided by the watershed approach. Over the project’s 20-year crediting period (2017–2036), it is projected to avoid ~73,463 tonnes of CO₂e, with over 24,000 tonnes already verified. Roughly 90% of reductions come from avoided electricity use; the remainder from avoided chemical inputs.

Market Momentum: First Credit Sales to Water Environment Federation and Mortenson

Following credit issuance, Virridy and the District are proud to announce two initial credit sales:

“WEF is proud to announce the District as our official WEFTEC climate partner and support Yahara WINS as a pioneering model that brings together watershed health, regulatory innovation, and climate leadership,” said John Ikeda, WEF Chief Mission Officer. “By integrating this project into WEFTEC 2026, the largest water quality exhibition in North America with a diverse global audience, we’re hoping to catalyze deeper connections between climate emissions and sustainable water management.”

“Mortenson is committed to reducing our climate impact, and we’re proud to support high-integrity, water-focused carbon projects like Yahara WINS,” said Mark Mortenson, Chief Investment Officer at M.A. Mortenson Companies Inc. “As a privately held company headquartered in the Midwest, we love how this project helps improve water quality and biodiversity in our region while avoiding climate emissions – setting a new bar for how infrastructure, environment, and carbon finance can work together.”

A Replicable Model for Climate-Resilient Watershed Management

The District’s leadership in adaptive watershed management has long been recognized for its innovation, but the issuance of carbon credits now creates a new revenue stream to sustain and expand these practices. The partnership with Virridy demonstrates how utilities can comply with Clean Water Act obligations while delivering verified climate benefits, with direct financial value in global carbon markets.

“This project proves that watershed management isn’t just good policy—it’s good climate strategy,” said Evan Thomas, CEO of Virridy. “By valuing avoided emissions, we’re unlocking new tools to finance compliance and resilience at the same time.”

With ongoing credit issuance expected annually, the Yahara WINS project is positioned to serve as a model for other U.S. utilities and watershed programs looking to achieve climate-aligned regulatory compliance. Virridy’s work to develop the Regen Registry’s ‘watershed carbon’ methodology and pilot collaborations with Madison Metropolitan Sewerage District and other wastewater facilities in Wisconsin and Colorado was supported by the Gordon and Betty Moore Foundation, the Walton Family Foundation and the National Science Foundation’s Convergence Accelerator.

About Virridy

Virridy specializes in water-focused carbon credit generation, leveraging digital monitoring, reporting, and verification (DMRV) technologies to quantify water and climate benefits. With expertise in carbon finance and water resiliency projects, Virridy drives investments in sustainable water management across the globe.

About the Madison Metropolitan Sewerage District

As a regional clean water utility, Madison Metropolitan Sewerage District collects, conveys and treats wastewater for 24 Madison-area municipalities and utility districts, recovering valuable resources in the process. Established in 1930 as a municipal corporation to protect the lakes and streams of the upper Yahara watershed, the District’s mission is to protect public health and the environment for the approximately 435,000 residents and businesses it serves. The District treats about 37 million gallons of wastewater daily at the Nine Springs Wastewater Treatment Plant.

About Mortenson

M. A. Mortenson Companies Inc. is the parent company of Mortenson Construction, which is a U.S.-based, top-25 developer, builder and engineering services provider serving the commercial, institutional, and energy sectors. Mortenson’s expanding portfolio of integrated services helps its customers move their strategies forward, ensuring their investments result in high-performing assets. The result is a turnkey partner, fully invested in its customers’ success and improving the communities in which they live and work.

About WEF

The Water Environment Federation (WEF) is a not-for-profit, nonpartisan organization providing water professionals with the latest in education and training. WEF is leading the transformation to the Circular Water Economy: reducing waste, recovering resources, and regenerating ecosystems. Founded in 1928, WEF’s mission is to inspire its 31,000 members and 75 affiliated member organizations and the water community in pursuit of human and environmental well-being. WEFTEC, WEF’s premiere event, is the largest annual water quality exhibition in North America, attracting a diverse, global audience. More than 20,000 registrants and 1,000 exhibitors convene at WEFTEC to exchange innovative ideas and solutions, conduct business, and share expert insights that positively impact the future of water. For more information, visit wef.org.

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