Marshfield No. 6

About Marshfield No. 6

The primary purpose of Marshfield No. 6 is hydroelectric. The dam generates hydroelectric power by channeling water through turbines, converting the energy of flowing water into electricity. The dam is owned by Green Mountain Power Corp (public utility). It impounds the Mollys Brook near Cabot.

The dam stands 48 feet tall and stretches 1,100 feet across, creates a reservoir covering 411 acres, has a maximum storage capacity of 13,526 acre-feet, and collects water from a drainage area of 19 square miles. Completed in 1927, the structure is well-established, with more than 75 years of service.

This dam carries a high hazard potential classification, which means that a failure or uncontrolled release of water would likely cause loss of human life. This classification reflects the consequences of failure, not the likelihood — it indicates that people live or work in the area downstream. The most recent inspection on record was 01/01/1987. That was 39 years ago — unusually long for a high-hazard dam, which typically requires more frequent inspections.

At 48 feet, this dam is taller than 92% of dams nationwide.

Living Downstream

If you live or work downstream of this dam, consider taking these steps: learn your local evacuation routes, check whether your county emergency management office has a dam failure inundation map, and sign up for local emergency alerts. The Vermont dam safety program can provide more specific information about emergency planning for this structure.

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