Increasingly intense storms such as last year's Tropical Storm Henri — its aftermath pictured here in Manchester — are one of the factors overburdening Connecticut's wastewater treatment facilities, state officials say. (Cloe Poisson/Cloe Poisson)

Wastewater treatment facilities in several Connecticut municipalities, which are more than a century old and are strained beyond their capacity partially because of climate change, will get major upgrades in a $580 million funding round announced by Gov. Ned Lamont.

Scheduled for upgrades, improvements and maintenance are the Metropolitan District in Hartford; the Greater New Haven Water Pollution Control Authority; Norwich Public Utilities; the City of Bridgeport; and water-processing authorities in Litchfield, Plainfield and Ridgefield.

“Connecticut has some really old cities with combined sewer systems meant to convey domestic sewage as well as storm water. A hundred-some-odd years later, the system pipes built for that purpose don’t meet current needs,” said Nisha Patel, director of Water Planning and Management for the state Department of Energy and Environmental Protection.

The two-year projects are financed by state and federal Clean Water Funds, which include $507 million from the state and $73 million from the federal government. The federal funding was augmented by the recently adopted Bipartisan Infrastructure Law.

In recent years, untreated sewage has seeped into rivers and streams and the Long Island Sound as a result of system inadequacies, Patel said. This causes unhealthy conditions for people — leading to closure of swimming areas — and for the wildlife in and near the water.

DEEP Commissioner Katie Dykes said water-treatment staff in Meriden, whose facilities got funding for upgrades in 2019, “talked about seeing fish in the river for the first time.”

Dykes said accelerating climate change is to blame for the increasingly extreme weather that overburdens the treatment systems.

“These challenges of raw sewage entering waterways during intense rainstorms are becoming more pressing as climate change accelerates,” Dykes said. “People think of climate change as sea level rises and coastal issues. It is also affecting inland communities.”

A total of 18 upgrade projects in those municipalities will be supported by the funding. All the projects are ready to begin now, said Dykes. “This is a major job creator,” she said.

Patel said the contamination of waterways doesn’t involve drinking-water systems, but is nonetheless essential to the quality of life in the state, for people and animals.

“You’re not drinking directly out of rivers or Long Island Sound. ... But all water is connected,” she said. “We need to make sure the water flowing through rivers, streams and the sound can support diverse wildlife species. They are part of our overall environment and it’s critical to maintain quality to meet that need.”

Susan Dunne can be reached at sdunne@courant.com.