Water, water, everywhere, but no way to swim upstream.

That, says a forthcoming study by the environmental engineering firm Milone & Macbroom, is the problem facing American Shad who have returned to the Neponset River in encouraging numbers in recent years. Shad and other fish are hampered in their attempts to navigate the river by unhealthy levels of PCB contaminants and several obstacles too large to swim or jump across, including the Baker Dam in Lower Mills.

Last Thursday evening, Jim Macbroom of Milone & Macbroom summarized the results of his firm's study during a heavily attended public meeting at the Hyde Park Community Center. Macbroom explained the environmental challenges facing the river and its aging dams, and outlined the pros and cons of several long-term solutions, including dam removal, dam repair, or a range of intermediary solutions such as the construction of a "fish ladder," an apparatus that would allow shad and other gilled river dwellers to swim upstream over the dam.

Leading up to Thursday night's meeting, computers across the Neponset basin were flooded with e-mails after an initial message sent by Ian Cooke, executive director of the Neponset River Watershed Association, to a list serve of association members prompted a blogospheric flurry of debate in which writers came down on both sides of the dam removal issue.

Cooke believes future health of the river is dependent upon the future of the Baker dam. "It's fair to say the Watershed Association is interested in removal of the dam," said Cooke. "The dam is fifty years old now, and is itself in a state of disrepair, so some decision needs to be made here."

A dam has stood at or near the Baker's present location since 1639, while the current structure, owned by the Department of Conservation and Recreation (DCR), has been holding back the river since 1956. In 2002, the Army Corps of Engineers embarked upon a study to assess the environmental impact of several dams along the Neponset, and to weigh the ecological and economic costs of removal or modification. That effort ran short on funding in 2003, only to be revitalized by Macbroom, who will release his completed study at the end of this month.

The structural integrity of the dam itself was analyzed in a separate, state-funded study released Tuesday. The dam was found to be in fair condition, meaning that it is in no immediate danger of failing, and must be re-inspected in five years. However, the DCR also opted to raise the danger rating associated with the dam's failure from low to significant. That means that were the dam to fail, major property damage and even loss of life could result.

"I am very concerned about the direction they're moving in," said Adam Street resident Doug Smith. "The dam is the lynchpin of the Lower Mills historic landscape. I'm thinking, what happens if that dam isn't here?"

Dorchester Historical Society President, Earl Taylor, agreed with Smith, saying that while the society had yet to develop an official stance, he was in favor of preserving the dam.

"It might be time to get involved," said Taylor. "Preserving this dam is worth discussing."

Tim Purinton, a rivers restoration planner for the state organization Riverways, said that Riverways coordinated the efforts of the Army Corps, Macbroom, and local residents, but that the DCR will emerge as the final decision maker.

"They hold a lot of the cards, and to this point, they haven't indicated a preference," said Purinton.

Both Purinton and Vanessa Gulati, assistant press secretary for the DCR, stressed that community input would be a part of the decision-making process, along with several crucial factors that extend a timeline for any final decision and subsequent construction well into the future.

"We're talking about a lengthy process full of regulatory permitting and the kind of public vetting that befits a project like this," said Purinton. "We might be looking at a final engineering plan in the next year, public outreach, and three to four years before any shovel hits earth."