NEWBURYPORT — A project seeking to improve the city’s drinking water by reducing algae from its source is expected to be completed on schedule with work finishing today, according to officials.
“The DPS Water Division is wrapping up the second phase of the alum treatment project in the Artichoke Reservoirs,” Mayor Sean Reardon said in his update submitted to the City Council for its meeting Monday.
Ward 6 City Councilor Mary DeLai spoke about the progress being made in her weekly correspondence to constituents.
“This past week, the water division completed the alum treatment of the Upper Artichoke Reservoir and moved on to the Lower Artichoke,” DeLai said. “They are very pleased with the results for both the clarity and the color of the water.”
The city draws most of its drinking water from the Lower and Upper Artichoke reservoirs, along with the Indian Hill Reservoir in West Newbury and Bartlett Spring Pond.
If algae blooms are not managed appropriately in the reservoir, toxins that could be released are unable to be treated at Newburyport’s water treatment plant, according to Water Treatment Operations Superintendent Pete King.
In terms of when the blooms are a problem, King said they usually pop up as early as May and stop appearing about October. He said they have had them almost every year in recent memory except for 2023 due to how wet the summer was.
The city had a localized algae bloom affecting the Plummer Spring Bridge area as well as the upper dam area of the Upper and Lower Artichoke reservoirs in October. The bloom wound up being the cause behind a brief but noticeable drop in water quality last month.
Alum treatment is a process where aluminum sulfate when added to lake water removes phosphates through precipitation, forming a heavier than water particulate known as a floc. This floc then settles to the lake bottom to create a barrier that retards sediment phosphorus release, according to the North American Lake Management Society.
The alum will bind with phosphorous and prevent it from feeding the algae, and is expected to last longer than the standard algaecide treatments the city has relied on in the past.
Reardon said the treatment remains on schedule to be completed today.
“The Water Division, in coordination with our consulting limnologist team, will continue monitoring conditions throughout and following the treatment process to document improvements and ensure the continued safety and quality of our drinking water supply,” Reardon said. “As previously noted, the project is also coming in well under budget, and we are very pleased with the results to date.”
It was revealed during the City Council meeting April 27 that the project was set to come in at $350,000, $250,000 under the expected cost. That same night, the council approved a $220,000 transfer from water enterprise retained earnings to watershed improvements to help fund the project.
Matt Petry covers Amesbury and Salisbury for The Daily News of Newburyport. Email him at: mpetry@northofboston.com.