After investing billions of dollars to upgrade treatment plants in New York and Connecticut, scientists are seeing a healthier environment on the Long Island Sound.

The 2018 Long Island Sound Report Card gives the eastern narrows a B minus, with water quality improving out further east.

Estuaries like the Long Island Sound are known as "nurseries of the sea" because many species birth and nurse in them. So keeping these habitats clean and healthy is key to support those ecosystems.

"What we're hoping is that we can return the water quality to Long Island Sound that supports this really diverse system of animals and plants living together, and that it carries us into the future," says Tracy Brown, the director of the organization Save the Sound.

Brown says that the Long Island Sound contributes to upward of $17 billion to the region’s economies every year in environmental and economic benefits.

Scientists tell News 12 this grade doesn't have to do with how safe it is to eat shellfish or whether it is safe to go swimming. They believe beaches on the sound continue to face their own challenges.