On Monday March 15, during the heaviest rain storm in recent Massachusetts history, MWRA made two controlled releases of flows from the Nut Island Headworks into Quincy Bay. The total discharge has been calculated to be between 5 and 10 million gallons.
The releases were necessary to prevent the Headworks, which had been operating past capacity for days, from flooding out and causing sewer overflows into Quincy’s Hough's Neck and Island Avenue neighborhoods. The releases also prevented a potential facility shut down that would have cost months of work and several million ratepayer dollars.
Bacteria samples taken on Tuesday morning showed levels in Quincy Bay that were somewhat elevated but still within swimming standards. At the tip of Nut Island and on the Hingham Bay side, bacteria were moderately elevated above swimming standards. However there has been such a large amount of contaminated runoff directly and from rivers and streams that is is likely all the waters including the harbor, rivers and streams, in the greater Boston area are showing signs of contamination.
The March 12-15 storm was of extraordinary proportions. Rainfall was over 8 inches in some areas, making it at least a "50-year storm" in weather terms. During the storm, MWRA’s Deer Island and Nut Island treatment plants processed record flow amounts and both facilities performed as designed.