(CBS) — Illinois’ meandering rivers can be a beautiful sight, but they need to mussel up to stay healthy.

Freshwater mussels help keep these eco-systems healthy, and they’re dwindling in number.

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“We are losing them,” says Jessi DeMartini of the DuPage County Forest Preserve District.

Illinois waterways were once home to 80 species of freshwater mussels, but 17 are now extinct and another 23 are either endangered or threatened.

“In the water world, everybody kind of needs each other,” DeMartini says.

That’s why in the tanks and basins of the Forest Preserve District, they are cultivating thousands of mussels to release back into the rivers.

The mussels are living filters, eating bacteria and algae that cloud up waterways.

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“They take all that and they hold it in,” DeMartini says.

Mussels are eventually transferred to larger tanks, where they’ll grow to a size suitable for release.

They will be marked, some even equipped with radio transponder to track their progress.

The mussels have been nurtured along since last winter.

By fall, 9,000 will be released into the DuPage River.

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