By Kendra Raymond
The recent salmon egg retrievals that were conducted at Mill Street dam, also known as Panther Run, in Raymond were much easier this year, thanks to some major improvements that took place over the summer. Fisheries biologists and culturists are wrapping up the yearly “egg take” from salmon as they make their way up the Jordan River from Sebago Lake to spawn.
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| Restoration work performed this summer at Mill Street dam in Raymond is shown. PHOTO BY RICHARD PARKER |
In recent years, the dam has become dilapidated and deemed unsafe after years of use and it became apparent that it was time to deal with the issues before there was a major failure.
Panther Pond Association member Bill Brennan said he’s pleased to see the renovations completed.
“Given the unfortunate circumstances surrounding the Dundee Park dam failure in Windham and results thereof, the Mill Street dam is a positive story,” he said. “I also know that these dams are aging out. The Town of Raymond is dealing currently with a request for the Dingley dam at Thomas Pond.”
Richard Parker is the Director of the Engineering Division for the Maine Department of Inland Fisheries and Wildlife. He emphasized that it was time to get the repairs underway.
“The water control structure of the dam was badly deteriorated posing unsafe conditions for staff who were tasked to manipulate the gate elevations to control water levels of Panther Pond,” he said.
Vital conservation role
The Mill Street dam plays a vital role in conservation of the area.
“The dam has two main purposes. It controls the water level of Panther Pond upstream. Secondly, it is crucial to provide water and flow to allow biologists to entrap spawning salmon for the purpose of removing the eggs to use to raise additional salmon at the hatchery,” Parker said. “Without the dam, water levels would be extremely low in Panther Pond. I would say it is very important to the community.”
Dam renovations began in May and were completed at the end of October, just in time for the spawning season. The process was involved and required a significant amount of planning.
Parker outlined the process.
“Steel sheet piles 30 feet in length were driven 12 inches upstream from the existing concrete structure to eliminate water seeping under the dam. Hundreds of yards of badly deteriorated concrete on the structure were removed to a point where the existing structure was solid, forms were erected, and new concrete with extensive reinforcement was installed,” he said. “The gate structure and gate were 100 percent replaced with new materials, and the right embankment received extensive drainage improvements and a new concrete retaining wall. One exiting upgrade that was made was the height of the left and right ogee on each side of the gate. The elevation of the left ogee is set to the ideal elevation of Panther Pond so water can naturally leave the impoundment without the necessity of opening the gate. The right ogee is set 3 inches higher than the left so it can alleviate high water caused by a storm. If rain events are extreme, then the gate can still be opened to evacuate the excess flow, but our hopes are this will only occur on a limited basis.”
Association involvement
PPA played a significant role in the renovations, as related by the Panther Pond Association Fall 2024 newsletter.
“Mill Street Dam is owned by the state of Maine and managed by the Maine Department of Inland Fisheries and Wildlife. The dam is critical for IFW in support of the fisheries hatchery activities focused on salmon spawning at the building adjacent to the dam. Many years ago, the state established a target water level for Panther Pond at 280.5 feet above sea level and have been managing to the target level ever since. This level assures there is enough water in Panther Pond to support a mid-October – late November release of water into the Jordan River of sufficient volume to allow salmon to migrate up the river to spawn. These salmons use a fish ladder to get into the building where they are milked for eggs, fertilized, and moved to the IFW fish hatchery in Casco. The salmon are then returned to Sebago Lake. The smolt are used to stock many lakes in Maine, including Panther Pond and Sebago. With a scientific name Salmo Salar Sebago, these fish have thrived as far away as Patagonia in Traful Lake and river.
“The old dam required a flood gate to be continuously opened and closed for management of the Panther Pond level with the goal of achieving the target level of 280.5 feet,” the newsletter article said. “Lake levels can fluctuate materially as most recently witnessed in the spring of 2022 and 2023. In 2022, many docks installed in mid-April were 6-12 inches underwater by the end of the month. Two significant rainstorms caused the lake to rise over a foot over a period of 4 to 5 days post-storm. The opening of the flood gates allowed the lake to subside, and it took around 3 weeks for the level to recede to the level it was at when the docks were put in. The results from the manual opening of the gate were a combination of art and science, with the goal of achieving the target level.”
PPA has good historical data on lake levels which fluctuate continuously depending on the extent of rain, melting, and other weather events.
According to the article, the new dam uses spillways to manage water levels, and the heights have been set and are completed.
“On Sept. 18, 2024, the lake level was 3 inches below the target level. There has been no material rain event in September to bring this level up and the dam is not releasing any water. The 2 inch drop below target level can be attributed to a combination of evaporation and some water seepage at the construction site,” information in the article cites. The engineering design of the new dam differs from the old dam in that the spillway height has been set to hit the Target Level of 280.5 feet, requiring no manual opening of the flood gate. Any water above the target level will naturally flow over the spillway until the target level is reached. A significant rain event will raise the lake level, and the spillway will overflow until the lake is back down to the target level. The PPA will be monitoring the lake levels of the new dam to determine how long it takes the lake to settle back to target levels after rain/melt events under the new dam engineering design.”
Salmon migration
On or about October 18, 2024, the flood gates were opened, bypassing the spillways, to release enough water into the Jordan River to allow the salmon to migrate from Sebago Lake to the dam to spawn. This flow will be maintained until late November and the fish will return to Sebago. In the absence of any material rain event, this will cause the lake to drop below the target level. This drop could be a material drop if there is no rain to offset the draw down.
Association members say the lake is very low, and many have commented that they have never seen it so low. Brennan concurs and believes that the lake should not drop much lower since the salmon drawdown has been completed.
“There is minimal water passing through the flood gate on the dam,” he said. “We have also experienced a lack of significant precipitation since August.”
The salmon milking on Nov. 13, was a success with more salmon in the milking house and in the pool below the dam than anyone can remember, he said.
“The lack of any meaningful precipitation created a condition where Panther Run was one of the few streams dumping significant water into Sebago Lake,” Brennan said. “IFW believes this concentrated the salmon into Panther Run and some estimates suggest that over 1,000 fish that made the journey to Mill Street dam. It was quite a sight to see all these salmon swimming up Panther Run and then settling into the pool below the dam. We hope mother nature provides the precipitation and deep snowpack that will be needed to refill the pond by spring.”
Brennan agrees that PPA is committed to the health and preservation of Panther Pond.
“The mission statement is about the water quality and ecology of the pond,” he said. <
