From passing a landmark 100% carbon-free commitment to expanding solar access, Minnesota has stood out this year as a national leader in advancing clean energy. These legislative victories were years in the making and have the potential to usher in a resilient, clean energy future for Minnesota.

But passing bills — no matter how transformative — is only one piece of the pie. Building on our clean energy momentum also requires leadership from the state’s energy regulatory body, the Public Utilities Commission (PUC). This summer, the PUC is faced with a decision: advance our 100% clean future or send us backward.

Great River Energy (GRE), an electricity cooperative that provides electricity to 1.7 million member-owners across Minnesota, has proposed what it calls a “minor alteration” to its gas-fired power plant in Cambridge, Minnesota. The company’s proposal requests a permitting change that would allow for “dual fuel” — in other words, adding dirty diesel oil to its energy mix.

By framing the proposed change as “minor,” it’s evident that GRE is counting on the PUC to act as a rubber stamp. Per Minnesota statutes, an alteration deemed “minor” is able to bypass the environmental impact statement typically required for these kinds of facility changes.

In reality, adding diesel to the Cambridge plant is anything but a small tweak. If approved by the PUC, this move would not only fly in the face of our historic clean energy progress; it also has the potential to do substantial harm to the health of Minnesotans and the environment. As Minnesota’s authority on energy regulation, the PUC is responsible for ensuring that utilities act in the public interest. Their choice should be a simple one: reject GRE’s proposal and require a thorough environmental impact review for any new fossil fuel projects.

Diesel is a polluting fossil fuel notorious for its harmful emissions, which can cause and exacerbate health concerns like asthma and heart disease. Proximity to fossil fuel burning facilities means that rural and low-income Minnesota communities are already disproportionately exposed to pollutants in their air, soil, and water. Cambridge is no exception.

Increasing diesel emissions  — both via the plant itself and the trucks that would be required to deliver the diesel oil — would only worsen health harms. We also can’t discount construction impacts like increased traffic, emissions from heavy equipment and noise pollution, all of which can adversely impact health and quality of life. Among those likely to bear the brunt of added pollution: kids attending a nearby K-12 school and families enjoying a popular community park.

Beyond the impacts on air quality and public health, adding more polluting fuel sources of electricity runs counter to our clean energy goals at a time when we should be doing everything possible to accelerate toward them. We should be investing in renewable and storage solutions not doubling down on polluting energy sources. That’s how we speed our transition away from fossil fuels, while simultaneously strengthening our grid and keeping bills affordable for Minnesota families.

Minnesotans overwhelmingly recognize the need for a swift energy transition — which is why we elected a Legislature that we knew could deliver. Now, it’s time for our commissioners to serve the people they work for.

Minnesota’s commitment to 100% clean energy legislation was a powerful declaration of our determination to combat climate change and transition to a sustainable future. Giving utilities free rein to undermine that commitment is an affront to this banner achievement and to the many years of activism by countless Minnesotans that it took to secure it. The Public Utilities Commission must use its authority to send GRE’s proposal back to the drawing board.

Jenna Warmuth is the Midwest regional director for Vote Solar. Maggie Schuppert is the campaigns director for Clean up the River Environment (CURE). Both are Minnesota residents.