West Harbor Pond’s broken 1880 siphon plugged at last

Wed, 03/30/2022 - 8:45am

    West Harbor Pond’s water quality problems have always had a single source: saltwater. Normal freshwater lakes experience seasonal turnover that reoxygenates the lake’s water, rejuvenating the health of the aquatic environment. But saltwater is heavier than freshwater; and the saltwater that accumulates at the bottom of our Pond interferes with seasonal turnover and promotes the build-up of hydrogen sulfide, which is the natural product of vegetative decay in an anerobic environment.

    In 2018, the West Harbor Pond Watershed Association, with generous financial support from the community, replaced the broken 1880 siphon with a new siphon that removed the deoxygenated, hydrogen sulfide-infused water from the Pond down to the 25’ level. By the fall of 2020, this repair allowed the Pond to turn over seasonally to the 20’ level in the upper basin and to the 25’ level in the lower basin, reoxygenating water that previously had been severely deoxygenated.

    However, the Pond continues to receive regular infusions of saltwater, which floods into it in large quantities during the king tides that occur each spring and fall. During these king tides, significant amounts of saltwater from the inner Harbor enter the Pond in two ways: 1) by overtopping the small dam in the box culvert and 2) by flowing through the old, broken 1880 siphon.

    This week, one of these entry points for saltwater was permanently closed when the Department of Transportation, with the assistance of the Boothbay Harbor Sewer District, plugged the 1880 siphon by filling its horizontal member with grout. Before the siphon could be grouted, however, the vertical members at either end had to be plugged to prevent the liquid grout from escaping into the Harbor or the Pond. Boothbay Harbor Sewer District personnel cut an opening in the Harbor-side elbow and placed a plug in the Pond-side elbow. DOT personnel then filled the harbor-side member with pea gravel through this opening and capped it with a concrete plug. On Monday, March 28, DOT completed the plugging operation by filling the vertical member with grout, forever sealing this passage to saltwater from the Harbor.

    The West Harbor Pond Watershed Association wishes to express its deep gratitude to Chris Higgins and David Pratt of the Boothbay Harbor Sewer District; Brian Reeves, Midcoast Region Engineer, DOT; Randy Butterfield and Jacqueline Babine, Transportation Operations Manager and Transportation Crew Supervisor respectively at DOT Edgecomb; and Maggie Fairbrother, a member of the WHPWA’s Board of Directors, who worked with the BHSD and DOT to bring this to pass.