Solar devices to combat algae

Six solar-powered machines designed to combat algae blooms that have blighted a cherished Mashpee pond in recent years made their debut early this spring.

The machines, installed by the North Dakota-based company SolarBee Inc. on March 21, were purchased with $357,000 in Community Preservation Act funds. The solar panels, mounted on floats, provide power for turbines that drive oxygen-rich surface water toward the pond’s bottom, decreasing the amount of phosphorus that is released.

The devices are spaced throughout the mile-long Santuit Pond, which has been closed to swimming for significant periods over the past two years, according to Mashpee Public Works Director Catherine Laurent. She said that the 172-acre pond is notable because it serves as a spawning ground for herring and has archaeological and historical significance for the Wampanoag Indian tribe.

While some of the phosphorus detected in a 2010 study was of natural origin, Laurent said, much of it was caused by surface run-off, including fertilizer.

“Because of the anaerobic condition, [the phosphorus released from the sediment] ended up being robust, causing this algae bloom, which just kept getting worse over the past two years,” Laurent said.

A number of other New England communities, including Harwich, have made use of the SolarBee technology, according to Laurent. The experience of other towns suggests that it will take at least two years to achieve significant improvement, she said.