NORTHBRIDGE, Mass. - The Blackstone River Coalition is looking for volunteers to help monitor and maintain the health of the river running through Central Massachusetts and Rhode Island.

Water quality monitoring coordinator Heather Parry said the Blackstone River was highly industrialized in the past.

The National Park Service said it ranks among the top five most-polluted rivers in the United States.

“We’ve seen over the course of recent years the nutrient levels have dropped significantly,” said Parry. “And we’ve also seen lately there’s been a lot more flooding, especially this year and last year, especially the main stem of the Blackstone.”

The nonprofit operates out of 75 sites across Worcester County and Rhode Island.

Volunteers will go out monthly to inspect the water before bringing samples back to the lab for testing.

Perry stopped by the Blackstone River and Canal Heritage State Park Sunday morning to give Spectrum News a demonstration.

“We sample for turbidity, conductivity, temperature, nutrients, which includes orthophosphates and nitrates,” she said.  “And we also monitor for things like erosion, trash, just the general condition of the river.”

Perry said the coalition has seen more people use the river in recent years for recreational purposes, like fishing and boating.

She said people can keep the river safe for public use by addressing habits leading to nonpoint source pollution.

“How much fertilizer people put on their grass or storm drains that empty into the rivers, because any storm drain that you see in the street ends up in a water body usually,” she said.  “But it is getting a lot better from what it was. That’s what we see in our data but we want to keep going in that direction.”

People interested in volunteer opportunities with the Blackstone River Coalition can reach out to them through their website.