Morses Pond in Wellesley is on its way to restored glory: The third phase of a cleanup that has taken many years began this month with the launch of the Northern Basin Dredging Project.
The manmade pond covers about 105 acres, providing a community swimming hole
and contributing to the town’s water supply. There are three wells that sit in the same aquifer as Morses Pond, and these wells supply about 30 percent of the town’s drinking water, according to Bill Shaughnessy, Wellesley’s water and sewer superintendent.
Sediment has been building up in the pond since the 1970s, when the pond was last dredged, said Janet Bowser, director of the town’s Natural Resources Commission.
The dredging will help clear the water and restore the pond’s health. During the dredging, no swimming, canoeing, kayaking, or other water activities will be allowed.
The project will last until the end of the year. Crews were doing site preparation work early last week, and were expected to begin the actual dredging later in the week, Bowser said.
While some sediment buildup is natural, Bowser said, she estimated that about 80 percent of the buildup in Morses Pond has been caused by human activity.
The sand and salt that make it safe to drive on Route 9 in the winter wash down into the watershed and collect in the basin. Rain also washes gas and oil residue that collects on the road into the pond. Nearby homeowners use pesticides, herbicides and fertilizers, which make their way into the pond and encourage algae blooms.
The result — murky water choked by weeds. Fewer boats enjoy the pond, and swimmers stay close to shore. Bottom-feeding fish are losing their habitat.
Though some water from Morses Pond travels through the ground to the nearby wells, drinking water has never been affected by the buildup of sediment and chemicals, said Shaughnessy.
The sediment does not travel through the ground to the wells, and Wellesley’s drinking water is extensively filtered, aerated, cleaned, and tested before it is pumped out to homes.
During the Morses Pond dredging, a large suction pump will remove the sediment. About half of the dredged materials will be pumped and drained at the town beach to replenish its sand, according to a letter from the Natural Resources Commission.
The other half will be pumped to the parking lot of St. James the Great Church, which is closed. The dredged material will sit in “GeoTubes’’ — proprietary containers that drain excess water and consolidate the material — through next April. Then the material will be hauled off the site and clean water will be pumped back into the pond.
The dredging is the final piece of the restoration laid out in a 2005 plan. The first step involved harvesting invasive plants that had crept into the pond. Step 2 was to cut down on algae growth and help improve water clarity by installing a system to prevent phosphorus from entering the pond.
To keep the pond in pristine shape, the town is encouraging residents to use minimal amounts of fertilizer on lawns and gardens — or none at all. Fertilizers that feed lawns also feed weeds in the pond.
Residents are also encouraged to lay off the pesticides, which kill “good’’ bugs as well as the “bad’’ bugs they are intended for.
Other steps: Use phosphate-free soaps to wash cars; don’t dump hazardous materials into drains; and position rain barrels to catch storm runoff from roofs.
The dredging project costs $1,050,000, according to Bowser. In 2007, a Town Meeting and a townwide vote approved a $650,000 temporary tax increase to cover the project. But bids came back much higher than expected, said Bowser, and in June, Special Town Meeting voters approved spending an additional $400,000 in Community Preservation Act funds to bridge the gap.
The earlier two phases of the project cost a combined $403,000 in Community Preservation Act funds, Bowser said.