MAHOMET — On one hand, the numbers tell the tale.

“The 2019 USRC Sangamon River Mussel Survey at Riverbend Forest Preserve drew 59 volunteers (43 ­in-water). They found 559 live individuals, 13 live species, 14 extant species and 17 total species. Despite cool temperature, the enthusiastic group logged 46 total search hours for a catch per unit effort of 12.15. Results are not yet official,” Upper Sangamon River Conservancy officials posted this week on Facebook.

On the other hand, the tale is more about getting into the river. Helpers were winding along with its route, getting out in nature and getting those hands dirty and those clothes wet to explore the river bottom for mussels to, in a way, diagnose the health of the Sangamon.

Some of the volunteers who turned out were gray-headed, while others were youngsters who splashed a bit to play in the river as they worked, too.

“The weather could have been a little warmer. We had a very good turnout, and I think things went real well,” said Bruce Colravy, USRC president and coordinator of the group’s Riverwatch and mussel survey, which was held Saturday. “We didn’t get a huge number of species. You always hope you find something you haven’t found before. We got a lot of mussels. We got a lot of pistol grips.”

“Pistol grip” mussels are just one species and are named for their general shape.

As for what this week’s survey showed about the Sangamon’s fitness, Colravy said the abundance, diversity of species and number of young individuals are part of the equation to judge that.

“There are a few different factors,” he said. “Overall, with those things in mind, I would rate it between good and very good.”

Scott Hays, USRC secretary, a founding member and float trip coordinator, explained a bit about mussels after Colravy disappeared around a bend in the Sangamon leading a group of survey volunteers.

“The key reason to do the mussel survey is ’cause mussels are an excellent indicator of the health of the river,” Hays said. “The more that we find in the river, the healthier we can assume that the river is. So we look for two different things: the raw count of mussels and the number of the species diversity.

“Over the years ... we’ve identified up to 23 different species of mussels, and (collected) as many as over 1,000 at a single site north of here,” he added while standing on the river’s rocks Saturday at Riverbend Forest Preserve southwest of Mahomet. Illinois, in fact, has the most species of mussels anywhere in the United States, he said.

There’s a reason that mussels are looked to as a gauge of the Sangamon’s health.

“Mussels are dependent upon the fish species for reproduction and growth, and so there’s a symbiosis in the way that they originally populate the river,” Hays said. “And so mussels tell you about fish, and fish won’t survive if the river is toxic, and the less toxic the river is, the more mussels you’re going to find.

“The other half of the equation is that mussels also act as filters for the river,” he added. “So (they’ll) also help keep the river clean, so it’s a double benefit: They don’t exist unless the river is clean, and the more that you have, the cleaner the river’s going to be.”

According to Hays, Saturday’s volunteer turnout was the group’s best yet.

“That alone indicates just the popularity of the river,” he said, noting that the survey is in about its eighth year. “The community is very interested in what’s going on in the river.”

Mahomet resident Clyde Sweet had river water dripping off of him from almost head to toe after searching in the Sangamon for mussels. It wasn’t too long before he had a bag heavy with the various colored shells.

“I’ve always been interested in nature and it’s a fun activity to get out and learn about some things that most people don’t learn about,” he said about volunteering at the survey.

He said he hikes along the river frequently. He participated in the survey about three years ago, as well.

“I found a good sandy area,” he said, hence the good haul from the river.