It is the job of the Martha’s Vineyard Commission to weigh benefits and detriments when reviewing developments of regional impact. And at the moment the negatives appear to be tipping the scale heavily on the large solar array that the Oak Bluffs water district hopes to build on forestland off Barnes Road.

Under review as a DRI since last February, the project was planned with the best intentions: among other things it was reasoned that long-term savings generated by using renewable energy could be reinvested in future infrastructure needs for the municipal water department.

But siting a solar project on ancient forestland reminds us of that infamous quotation from the Viet Nam conflict: “It became necessary to destroy the village to save it.” Promoting one form of green energy at the expense of another seems like a bad idea, and leaders of the water district would be well advised to go back to the drawing board to explore alternatives.

The solar project has already been revised once; originally twice as big, it was significantly cut down over the summer, partly so as not to intrude on the protected zones around three municipal wells that lie on the 56-acre property. But it still would involve clear cutting ten acres of old-growth woodlands abutting the Manuel Correllus State Forest and the Peg Littlefield Greenlands. These are permanently protected conservation lands that, among other things, safeguard the Island’s sole source aquifer.

Enter a growing number of Island conservationists who are alarmed at the prospect of trading forest gold for green energy. Respected ecologists, including David Foster at Harvard Forest and Tim Boland at the Polly Hill Arboretum, argue that clearing a large swath of forest would cancel out the long-term environmental benefits of generating solar electricity. They note that roots and soil in the forest help remove pollutants and maintain groundwater quality. And they point to a decline in critical oak forests around the world as a result of development and climate change.

On top of that, at the commission hearing last week it came to light that if the project is built, the estimated 1.6 million kilowatt hours it would generate annually far exceeds the water district’s needs. The added financial benefit from unused electricity generated would accrue to BlueWave Capital, the company with whom the water district has contracted to build the project, not the town or the water district.

When it comes to building municipal solar arrays, Oak Bluffs is the last town on the Island to join the party. The five other towns have all built arrays in recent years; most are sited at capped landfills, repurposing otherwise vacant town-owned land. While Oak Bluffs town leaders have had their own solar discussions, it is not clear to what degree these have been have coordinated with the water district, which operates as its own governmental entity.

As technology has advanced and costs have fallen, solar energy is realizing its great promise of becoming a major source of clean, reliable alternative energy for Martha’s Vineyard. With a little more effort, officials in Oak Bluffs can surely come up with a plan that doesn’t pit one environmental good against another.