The water levels are far from reaching worrisome conditions, experts say.
10.18.2012 | BELCHERTOWN -- The spillway at Quabbin Reservior shows the lake's low water level.
Even though the drought in southern New England has been mild compared to conditions in other parts of the country, the water level at Quabbin Reservoir is the lowest it’s been at this time of year in nearly a decade.
Less than normal rainfall every month from November 2011 through April 2012, including a nearly snowless winter that sent little spring runoff into the massive reservoir, left Quabbin at 88.9 percent of capacity on Oct. 1.
But because it is so large – 417 billion gallons when filled – it will take perhaps years of drought to draw the Quabbin down to worrisome levels.
“Given Quabbin’s huge volume – it holds almost 6 years worth of water use – we are able to capture the extra water in wet years to more than make up for dry years. We’ve got plenty of water,” said Frederick A. Laskey, the executive director of the Massachusetts Water Resources Authority, which oversees the reservoir.
Quabbin Reservoir was created in the 1930s by the damming of the Swift River Valley, which required the flooding of four towns in the valley. The reservoir is the main water supply for much of eastern Massachusetts as well as Chicopee, Wilbraham and South Hadley.
Smaller reservoirs and ground wells can be easily depleted by persistent dry conditions or raised quickly with a few months of heavy rain. And, many in Hampden, Hampshire and Franklin counties that fell to low levels after the dry winter have recovered due to normal rains in August and September.
However, larger reservoirs typically need a much longer period of above normal rains to refill. In 1967, after more than four years of drought, Quabbin Reservoir fell to 45 percent of capacity. It was not until 1976 that it again reached full capacity.
Since January 2005, on average, Quabbin has been 96 percent full. The lowest point the reservoir has reached since 2005 was 87.6 percent full in January 2008.
Cobble Mountain Reservoir, the 22.5-billion gallon reservoir in Blandford that serves the city of Springfield, was at 72 percent of capacity on Oct. 1.
“The 10-year average for this time of year is approximately 78 percent,” said Katherine J. Pedersen, of the Springfield Water and Sewer Commission.
“We are not concerned at this point because summer is over, and that is our peak water-use season,” she said.
In most years, the melting of snow in spring raises the water level significantly in reservoirs. However, following the last snow season, when less than half the normal amount of snow fell in most of the Pioneer Valley, there was little snowmelt in the spring.
If the predictions involving global warming prove true, water officials fear that the spring runoffs will be less help in keeping reservoirs at desired levels in New England.