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The fish ladder in Damariscotta Mills has been in operation for over two hundred years. Built in 1807 by the combined efforts of the towns of Newcastle and Nobleboro, the fish ladder was constructed to allow alewives to bypass the mills blocking the falls between Damariscotta Lake and Salt Bay. Last winter we worked on capping the pools we built and the bottom of the ladder above and below the foot bridge. (Read more about the fish ladder below the slideshow...)
The fish ladder was originally built in dry laid stone on a seasonal overflow that was probably never an efficient passageway for fish because it followed the lay of the land, which is often steep and narrow. During the two hundred years since it was constructed, the fish ladder underwent many repairs and renovations but none of them were comprehensive or specifically designed for efficient fish passage. By 2006, the structure had fallen into extreme disrepair. In one section, a 2 x 4 piece of lumber was wedged to hold back a stone wall.
Recognizing that ad hoc repairs were simply an ongoing stop-gap solution, the Towns of Nobleboro and Newcastle and the Nobleboro Historical Society, backed by a solid community-based initiative, embarked on an ambitious rebuilding project in 2007. During the first phase, a deteriorated section of wall forty feet long and twelve feet high was removed and rebuilt. In 2008, the US Fish and Wildlife Service and the Maine Department of Marine Resources provided design services and technical support for more significant re-building. Out of this work, plans for a pool and weir fishway were provided by Curtis Orvis, fish ladder engineer for the US Fish and Wildlife Service.
Using the new plans, the fish ladder restoration progressed in stages (see drawing below). The upper third, which is the most accessible section, was re-built between 2008 and 2009. During the same period, many of the existing pools were modified using sandbags and rubber sheeting to meet the new design specifications. Fish counts began to increase in response to the improved fish ladder--from 150,000 alewives reaching Damariscotta lake to spawn in 2007 to 400,000 in 2009.
The middle third of the fish ladder was re-built, with the exception of wall capping, between 2010 and 2012 and work on the lower third, underway since 2012, is now nearly complete. Specifically, nine pools were re-built in 2013 and this winter the remaining sixteen pools are under construction. Additionally, the stone work on the upper walls and the capstones are being being installed on thirty pools that we're previously constructed so that, by year end, we expect the fish ladder restoration to be substantially complete.
The success of the new stone pool and weir fishway is well documented in the significant increase in the number of fish entering Damariscotta Lake to spawn. More than 500,000 fish were counted in 2012 and 917,000 fish made the ascent in 2013. These counts are higher than any ever recorded, confirming that the restoration project is making a significant positive impact on the Damariscotta River alewife run. It's exciting to think that the run will continue to increase, stabilizing the fish run and positively contributing to the health of the Gulf of Maine ecosystem.
The work this year has been helped tremendously by significant grants from the National Fish and Wildlife Foundation, the Elmina Sewell Foundation, the Horizon Foundation, and the Davis Conservation Foundation as well as by wonderful community support. We--and the fish--thank everyone-- the Damariscotta Mills Fish Ladder Restoration couldn't happen without all of us!
The drawing below shows the fish ladder layout before restoration on the left and the current status of the restoration on the right.