The Oak Bluffs water district continued to apply a low dose of chlorine to the Farm Neck well Thursday morning, after a 48-hour boil water order from the state Department of Environmental Protection had been lifted.
Several samples of town water were found to be contaminated by a total coliform fecal indicator Monday morning, mobilizing the town emergency management department and water commissioners to alert residents, and provide free water supplies.
The boil water order for Oak Bluffs was lifted at 11:30 Wednesday morning.
The water district closed the Lagoon Pond well Wednesday morning, allowing the order to be lifted, and will keep it shut for at least two weeks, said Paul Provost, interim superintendent at the town water district.
At that point, water commissioners will test the well and reevaluate it to determine if the water is safe to drink. They will continue to chlorinate the entire water supply at a dose of less than a quarter of a part per million until the state DEP recommends that they discontinue. The well has a capacity of 500 gallons per minute, and is one of six public wells in the town. The town water district has approximately 4,395 customers.
The water district could begin permanent chlorination of the water supply to hedge against these contamination events, but they would prefer not to, Mr. Provost said. Continuous chlorination is costly and time consuming, said Terry Dayian, of the DEP. “You have to monitor it every day, and send us a report every month with the values of the chlorine residual,” she told water commissioners when she visited the Island for a well inspection on Wednesday. As it is, water is sampled and tested monthly. Alternatively, the water district could decide to shut down the Lagoon Pond well during periods of high rainfall.
Over the course of 48 hours, the town’s emergency management team and the water district worked together to “immediately spring into action,” said town administrator Robert Whritenour. The town sent out reverse 911 notifications, and distributed bottled water. They are currently scheduling a post-event review with the water district and the emergency management team to evaluate the “good, the bad and the ugly,” of the response of officials during the 48-hour water situation, the town administrator said. The water district is a separate government entity that does not come under the direct control of the town government, Mr. Whritenour said.
The announcement that the boil water order would be lifted followed a site visit to the Lagoon Pond well Wednesday morning by water district officials with Ms. Dayian, who works with the DEP drinking water program.
Ms. Dayian examined the well site off Barnes Road for possible causes of the high bacteria count Wednesday morning. She said the water level in the pond and surrounding wetlands was higher than she’d ever seen it, and suggested that the proximity of the well heads to that increased volume of standing water may have allowed bacteria to collect.
The water district has provided instructions for the safe use of town water following a boil order. Residents are instructed to run tap water for a few minutes until it feels cold, before using it to drink, brush teeth or use in cooking. Residents may notice that the water tastes slightly different, Mr. Provost said.