Originally published in Wastewater Digest, March 2026.
MMSD and Virridy on the First Watershed Carbon Credits for Utilities
Wastewater Digest interviewed Martye Griffin, ecosystem services manager at the Madison Metropolitan Sewerage District (MMSD), and Alex Johnson, chief strategy officer at Virridy, about the Yahara WINS program and its implications for the water sector.
Cost Efficiency
"Tertiary treatment would cost nearly $200 million" over 20 years, Griffin explained, whereas watershed conservation practices were estimated at "significantly lower at about $35 million." This cost differential was central to the District's decision to pursue the watershed approach.
Conservation Practices
The most effective practices "keep nutrients on the land and in the soil" rather than allowing them to reach waterways. These include cover crops, low-disturbance manure injection, and reduced-tillage systems. "The greatest reductions occur when farms use two or more of those practices together," according to Griffin.
Replication Blueprint
Alex Johnson noted that other utilities would need "a formal life-cycle analysis comparing a conventional treatment upgrade with a watershed-based or green infrastructure approach" to generate similar carbon credits. The Yahara WINS model provides a blueprint for how watershed-based compliance can generate both environmental and financial returns.
Future Outlook
MMSD anticipates the program will continue adapting through 2036, including enhanced partnerships with the U.S. Geological Survey to optimize practice effectiveness. Program leaders believe watershed-based carbon credits could become integral to broader climate strategies across the water sector, particularly as regulatory pressures intensify and treatment costs increase.