Penobscot discoloration no cause for alarm

Over the weekend I began receiving emails that sounded pretty grim.

In a nutshell, veteran river-watchers on the Penobscot were concerned because the river was running brown, with plenty of sediment floating downstream. Members of the Veazie Salmon Club, who often meet at their clubhouse to play cards in the mornings (and who are, as you might guess, pretty passionate supporters of Atlantic salmon) sounded the alarm, and posted a video on the Internet.

Their fear: That the dirty-looking water, which they suspected had been caused by the ongoing process of tearing down the upstream Great Works Dam in Bradley, would harm or kill fish, including salmon.

Thankfully, that doesn’t seem to be the case. In fact, Jeff Reardon of Trout Unlimited and Andrew Goode of the Atlantic Salmon Federation were quick to reply to the concerns of salmon club members, and said that the discoloration, called “turbidity,” was a short-term problem that was to be expected as the Great Works Dam is dismantled.

“Let me assure you that there are many agency, Penobscot Trust staff, and volunteers monitoring the removal and taking numerous precautions to minimize any turbidity events,” wrote Goode, the ASF’s vice president of U.S. operations in an email. “Yes, in removing a big dam that has been in the river for 180 years there will be some short term disturbance but this is short term.  In the case of Great Works, a contractor was chosen in part due to their plan to build a smaller coffer dam, using smaller volumes of fill on the downside of the river rather than building a more traditional coffer dam above the dam that would have resulted in far more disturbance.”

Goode pointed out that the biggest threat returning salmon face on rivers like the Penobscot isn’t the existence of short-term “turbidity” events. Instead, it’s the dams themselves.

“Let’s be clear, it’s the main stem dams like Great Works and Veazie that are killing salmon and other fish on the Penobscot and not short term turbidity events in the river.  According to our ASF fisheries scientists with over 80 years combined experience, the short-term turbidity we are seeing on the Penobscot will not have any negative impact on salmon or other fish in the river,” Goode wrote.

“Short-term turbidity events caused by storms occur in many Maine and Canadian salmon rivers every year without fish kills.  The only fish kills ASF scientists have witnessed associated with turbidity has not been due to turbidity but rather to the chemicals being washed off nearby agricultural fields,” he wrote.

Reardon, the Maine Brook Trout Project Director for TU, one of the groups that joined together to make the Penobscot River Restoration Project a reality, was on-scene on Sunday, and also sent an explanatory email that he wanted to be shared with salmon club members and other concerned river-watchers.

“I was at the site [Sunday] until around 5 p.m.  At that time, the contractor had breached the cofferdam, and there was some turbidity in the river downstream of the construction site, Reardon wrote. “On my way home, I stopped along the river at the Eddington Salmon Club, and at that time no turbidity was visible that far downstream.”

Reardon,  who was pitching in on some mussel-relocation work, returned to the Great Works site at 4 p.m. on Monday.

“While the water was a little cloudy, it was a lot less turbid than what is shown in [the video],” he wrote. “I also stopped at the boat launch in Eddington on the impoundment, where no turbidity was visible.  There was notable turbidity at free-flowing river sections above the Veazie impoundment in Bradley, much closer to the construction site.”

Reardon said an on-line turbidity monitor run by the U.S. Geological Survey shows that the water condition deteriorated through the early morning hours on Monday, but had improved by Monday night.

“My guess is that there will continue to be some short-term pulses of turbidity during the remaining work on the cofferdams and draw-downs,” Reardon wrote. “This is common with dam removals and other large in-river construction projects, and we observed much the same thing with the removals of the Edwards, Fort Halifax, and Sandy River Dams in the Kennebec watershed. Turbidity impacts are typically short-term. In those other cases, no lasting effects of water quality or habitat were noted.”



Recommend this article
John Holyoke

About John Holyoke

John Holyoke has been enjoying himself in Maine's great outdoors since he was a kid. Today, he's the Outdoors editor for the BDN, a job that allows him to meet up with Maine outdoors enthusiasts in their natural habitat. The stories he gathers provide fodder for his columns, and this blog.