Recent test results show oxygen levels below the level needed to support a fish population.
|Sydney Richelieu, The Forecaster|
The Royal River appears stagnant upstream of the Elm Street dam in Yarmouth. In the fall, leaves pool on the surface as if on a pond. What was once a free flowing river that was home to indigenous trout and salmon lies dormant – no fish can survive here, the oxygen is too low.
Testing of the river last summer and fall bears that out, according to the Royal River Alliance, a Yarmouth-based organization advocating for the removal of the dams at Elm and Bridge streets.
“A free flowing river is healthier with oxygen levels than a slow moving river,” said Christine Force, co-chairperson of the organization. “It breaks your heart to think that these useless dams are causing environmental degradation.”
The Bridge and Elm street dams, no longer in use and acquired by the town in the 1970s, curtail the flow of the river and keep water temperatures higher, resulting in less-than-ideal conditions, Force said.
The Royal River is designated as a Class B river, which means it must have a dissolved oxygen level of 7 parts per million to support indigenous species of fish. The fish can’t survive if the dissolved oxygen level is less than 5 parts per million.
Seven volunteers trained by the Maine Department of Environmental Protection monitored four sites across the river in 2022, looking for oxygen levels at 7 parts per million or higher. Three out of four testing points had low levels, with 21 testing events showing dissolved oxygen levels under 7 parts per million, the alliance said. In some instances, the dissolved oxygen levels reached as low as 1.6 parts per million. The data collected by the RRA showed that the Royal River does not meet the Class B standard set by the state.
Carl Wilcox, an engineer and Royal River Alliance board member, said a driving factor behind the low oxygen levels is the water temperature.
“When the water is warmer, less dissolved oxygen can be in the water,” Wilcox said. “There is also natural bacteria in the water, as well as algae, which takes in oxygen.”
The lack of free flowing water allows the water temperature to rise, resulting in higher levels of bacteria and lower levels of dissolved oxygen. The slow moving water does not allow oxygen to mix into the river, so the deepest parts of the river become devoid of oxygen.
“Only the top 6 feet of the river, in the summer, has enough oxygen for a carp,” Wilcox said.
Not only do the dams prevent fish life, they also impact the larger food web of the river, according to Deborah Landry, a scientist and co-chairperson of the alliance.
