The Potter Valley Project, which dams Northern California’s Eel River, isn’t doing very much right now. Its reservoir is clogged with sediment , and drought often empties it out. The project once supported a hydroelectric power plant that could produce about 9 megawatts of electricity, which is about 1 percent of a typical fossil-fuel-fired plant, but it has not worked in years . Plus, some of its infrastructure may be at risk of collapsing during an earthquake. Like thousands of other small dams across the U.S., it is now more trouble than it’s worth. That’s why the utility that owns the project, Pacific Gas and Electric, moved last year to demolish it and undam the river. PG&E has wanted to abandon the project for decades, but a final removal agreement required years of careful negotiation.…