Mussel, fish surveys around Austin document the health of the Cedar River Watershed
The surveys, supported by local and state partnerships, help the watershed district monitor the health of its waterways.
AUSTIN — It's 9 a.m. and a trio of surveyors are already making their way through the foot-high waters of Dobbins Creek. With a big electrofishing pack on her back, Brenda DeZiel sweeps the creek bed with the electrified rod, stunning small fish that Jensen Bigelow nets and stores in a bucket. Their chest-high, waterproof waders protect them from the electric current's light buzz.
Maddy Merten, a summer intern at the nearby Jay C. Hormel Nature Center, takes the bucket back to the cement bridge to sift through the debris with her hands and sort the fish into different buckets and Tupperware containers by species.
The three, working on behalf of the Cedar River Watershed District, conducted an electrofishing survey on Wednesday, Aug. 24, 2022, near the nature center in Austin to collect data on the fish species present in the creek. That data will help CRWD staff gauge the creek's health.
"The information will be useful for looking at habitat changes over time, and if fish that are interested in certain habitats that are more specific will return and go upstream further as the sediment and the water flows are more rebalanced," said DeZiel, who was contracted for the survey through her company, Caddis Fish, LLC. Bigelow is also working on this project as a subcontractor. Last week she finished a year of service at the nature center through GreenCorps.
At the same time, about 15 miles south of Austin, a group of researchers from CRWD, the nature center and the Minnesota Department of Natural Resources, all in wetsuits and snorkels, surveyed a site on the Cedar River to check in on black sandshell and mucket mussels that were transplanted in the river a few years ago. The simultaneous studies showcase the CRWD's goal: improve water quality and reduce flooding along the Cedar River watershed.
"We've been plugging projects ... especially flood reduction projects that we know are reducing the amount of sediment that's getting further downstream," said Cody Fox, CRWD administrator. "We should be able to figure out if the water quality's improving, and with that data, it'll show the effectiveness of the amount of work that we're doing. ... Are we making improvements? Or are we not?"
Grants from agencies such as the DNR and the Minnesota Pollution Control Agency, which supports the Dobbins Creek electrofishing survey, make monitoring water bodies possible, Fox said.
"There's always money for (improvement) projects, but the monitoring is always kind of tricky," Fox said. "We want to build again ... and hopefully develop a trend line showing that species diversity and amount of fish and macroinvertebrates in those areas, especially more sensitive ones, are starting to hopefully improve and come in larger numbers."
In Dobbins Creek, Merten sorts the small fish, finding blunt nose minnows, suckers, southern redbelly dace and more. Partway through, a family stops along the trail to see what she's doing. She assures them that the stunned fish will recover – some of them are still belly-up.
"We usually can release them all," Merten said. "But sometimes on hot days, they don't do well in the tub.
"Some species can't tolerate pollution and a lot of sediment, so if we find them here, then it kind of tells us that the water's doing OK," Merten continued.
Meanwhile, several people stand thigh-deep or waist-deep in the Cedar River. One person uses a long wand to scan for passive integrated transponders, or PIT tags, and another person plants a green flag at the sites where the PIT tag reader gets a ping. At those flagged sites, snorklers dig for and gather the mussels, most of which were placed into river in 2019 and 2020 to restore their populations, said DNR lead propagation biologist Madeline Pletta.
"Since native mussels require host fish in order to move or re-establish population, fish from downstream ... are unable to move upstream because of dams," Pletta said, adding that mussel larvae attach themselves to the gills of walleye and other predator fish to complete their life cycles. "We've been able to utilize this (Legislative-Citizen Commission on Minnesota Resources) grant to then work on reintroducing state threatened and endangered species."
The black sandshell and mucket mussels spent the first year of their lives at the DNR's Lake City area fisheries. Then, they were moved to Eastside Lake in Austin to grow for another year before settling in their new home, the Cedar River.
"This is a marker capture survey, which really helps us identify growth, survival within the water that we're working at," Pletta said. "Hopefully, in five to 10 years, we will see natural recruitment where we'll be finding mussels that are not tagged, and then we can attribute that to our success, knowing that they're reproducing naturally within the system."
The oblong mussel shells measured between 1-to-2 inches across when the DNR transplanted them in the river. Now, Pletta says they're measuring up to 4-to-5 inches across.
As the thousands of transplanted mussels continue to grow and reproduce, Pletta said they'll reshape the ecosystem around them.
"Minnesota actually has these really important water purifiers — our own native mussels — that serve a really good purpose not only for reducing erosion within a river during high flow, because their muscular foot can hold the substrate together," Pletta said. "Other invertebrates are attracted to mussel beds. ... Think about it from a mussel to a midge to a mayfly to crayfish, all the way up to fish, you're going to create this really positive feedback loop just over a mussel bed."
Investing in the watershed's future
Fox says the CRWD's efforts to reduce flooding and keep the river's ecosystems healthy are made possible, in part, through funding from the Minnesota Legislature and state agencies. The data compiled from the Cedar River and Dobbins Creek will not only track the district's progress, but it will also help bolster the district's case for future funding when tax revenue from Minnesota's Clean Water, Land & Legacy Amendment phases out by the end of 2034.
"It'll be up for voting (on) whether that's going to continue," Fox said. "Well, we'll need data to show the money that we're putting on the land as part of projects — what are we getting out for this investment?
"Water is really important to us. We all know that," Fox continued. "We know that we're doing good things, but what is it actually showing in the stream?"
On Wednesday, the two survey teams got a little closer to answering that question.