Danbury’s drinking water violated federal standards
July rains, heat wave led to ‘minor’ violation; city says water is safe to drink
DANBURY — July’s excessive rain followed by a heat wave led the city’s drinking water to violate federal standards, officials said.
The city notified residents of the violation on Wednesday, with officials emphasizing the water is safe to drink.
“The important thing to know is that nobody’s water was ever harmful or dangerous,” said Mayor Joe Cavo, who described the violation as “minor.”
“The drinking water was fine,” he added.
Water in the Margerie Lake Reservoir exceeded standards for turbidity — or cloudiness — in the month of July.
The standard is that no more than 5 percent of turbidity measurements may exceed 0.30 turbidity units per month, but 5.8 percent of the city’s July samples exceeded these units, according to the violation notice.
The problem stems from a single day in July, which threw off average levels, officials said.
The unusual amount of rain, followed by a heat wave, caused an algae bloom in the Margerie Lake Reservoir, said David Day, superintendent for the public utilities department.
Algae blooms are not unusual, so the department is used to monitoring and treating them, he said. But indicators that typically predict a bloom, such as changing pH levels, didn’t show up this time, he said.
“We normally are on top of the algae blooms, but this one came on rather sudden,” Day said.
The plant was shut off for about five to six hours, with the West Lake Reservoir used as Margerie was treated, Cavo said.
Staff applied copper sulfate — an inorganic compound that destroys bacteria and algae — to kill the bloom, Day said.
“Once that got treated, we put Margerie back online,” Cavo said.
Turbidity levels returned to normal and water quality improved within a few days of the incident, according to the city’s notice.
What does this mean for the water?
The city was required to tell the state Department of Public Health of the violation, Day said. The state told the city that customers needed to be notified.
“We post it because the customers have the right to know,” Day said. “But if it was an emergency we would have sent a reverse 911 that day, but it never came to that.”
Residents do not need to boil their water or take other corrective actions, the city said in the notice.
“Turbidity has no direct health effects,” the city stated.
But residents with severely compromised immune systems, infants and some older residents may be at increased risk, according to the notice. Those concerned should consult their physicians.
Measuring turbidity indicates water quality and the effectiveness of filtration, including the presence of disease-causing organisms, according to the U.S. Environmental Protection Agency.
“Higher turbidity levels are often associated with higher levels of diseasecausing microorganisms such as viruses, parasites and some bacteria,” the EPA states. “These organisms can cause symptoms such as nausea, cramps, diarrhea, and associated headaches.”
Future upgrades
The Margerie Reservoir is more susceptible to algae blooms than the West Lake Reservoir, Day said. The latter is man-made, so it’s not as “naturally deep,” he said.
The department tests the city water multiple times daily to ensure it meets standards, but plans inhouse staff and contractors to conduct additional tests in the future, Day said.
He and other city officials are reviewing a draft facilities plan completed by consultants at the end of July to determine what upgrades are needed to the water system. That includes how to further address algae blooms at the Margerie Reservoir, Day said.
“We’re constantly using our existing tools, as well as our consultants, to make sure we stay on top of it,” he said. “It’s really an environmental condition that caused this, with the extreme weather events that are happening more frequently. And we’re looking to have plans in place to better deal with them.”