The Middlesex Fells Reservation was originally set up, in part, to protect Spot Pond, which provided the water supply for Melrose, Malden, and Stoneham.
Although those communities now get their water from the Quabbin and Wachusett reservoirs, Spot Pond is a backup reservoir, according to MWRA spokesman Jonathan Yeo. "It would only be used as a last resort in a serious emergency," he said.
The MWRA also has a covered storage reservoir in the Fells that is still in use, Yeo said. Water from Quabbin and Wachusett comes through the 20 million gallon high-service reservoir on its way to Melrose, he said, and the MWRA is looking for a site for another reservoir with a capacity of 25 million gallons.
"When we took Spot Pond and the old Fells reservoirs off line, we greatly diminished our storage in the region," he said. "Our master plan calls for additional covered storage to keep the water underground, away from humans and animals."
The MWRA is looking at six possible sites for the reservoir, one on land owned by The Gutierrez Co. and slated for development as the Stoneham Executive Center, and the other five on reservation land.
Although natural areas usually contain soil that absorbs storm water, the Fells consists of bedrock with very little soil, according to acting City Engineer Joe Lynch. "It has a limited capacity to absorb and retain water within the soil," he said. "In essence, the naturally occurring condition is that rain that enters the area almost immediately becomes runoff."
To keep dirt and hazardous chemicals out of Spot Pond, the MDC installed an underground drainage system in the 1950s and 1960s that directed all storm-water runoff away from the pond, Lynch said. One drainage tunnel runs beneath Melrose to the MDC channel near the Fidelity site at the southern border of the city. That reduced surface flooding in Melrose, he said, but as residents of the area around the reservation know, flooding still occurs during heavy rains. Under its "zero net runoff" storm-water provisions, the state does not require Gutierrez to solve that problem, Lynch said, merely to keep from adding to it.