Arboretum cleaning up ponds

The Arboretum’s Marion Dunn Pond and Secret Pond, which gather sediment and contaminants before they reach nearby waterways and ground water, are undergoing major improvements.

Steve Glass, Arboretum operations supervisor, says Marion Dunn Pond is being cleared of the sediment and pollutants. The sediment, which includes heavy metals such as mercury, zinc and cadmium, is being disposed of at a licensed site.

“The fact that these metals find their way into the pond means it’s doing its job,” Glass says.

The sediment must be dredged out every 15-25 years, Glass says.

The project and the presence of large, earth-moving equipment will significantly disrupt the area and close nearby sidewalks until mid-March. The project also requires the removal of some younger trees and shrubs. However, native oaks in the area will be protected and preserved.

The project improves the function of Marion Dunn Pond and nearby Secret Pond. Marion Dunn Pond will be re-contoured with a more gradual slope that will allow submerged and emerging native aquatic plants to survive and grow. Inlet and outlet structures will also be replaced.

The inlet structure to Secret Pond will be repaired, and, because the channel to the pond is severely eroded, it will be stabilized with fieldstone boulders.