A creek called Cada's south of Backus has mysteriously become filled with inches of sediment, but the source is unclear.
Cada's is a creek on the Pine River, south of Backus on Highway 87. It pools between the highway and the Paul Bunyan Trail. This area has been filled with some sort of sediment or substrate ranging from a few inches thick where the current is strong, to as many as 21 inches thick. Between 14 and 19 inches seems to be most common.
Considering directional boring to connect the Backus wastewater system to the treatment facility in Pine River runs through this area, it might seem likely that this sediment is a result of the boring, which has been disputed.
“I did take a look at it. There was some drilling mud that seeped in from the south side,” said engineer Greg Kimman of Short Elliot Hendrickson Inc.
Furthermore, following the discovery of the bentonite, Kimman said two officials from the DNR inspected the creek and said the stream appears to be in its natural state. Kimman came to the same conclusion. He said it was cleaned up within six hours of being discovered. The crew involved also installed a silt fence just beyond the south bank to prevent further runoff. Kimman said the clay had only run down the south bank and not much farther.
“When I was looking at it there is definitely a differentiation between where the drilling mud is and the natural creek, which is the middle of the area. It didn’t appear like there was a whole lot that got to the middle of that channel,” Kimman said. “The reason I say that is you look at the weeds and it doesn’t look like they’ve been covered up with any type of mud or sand or anything like that.”
Some locals familiar with the creek disagree.
Emily Davidson, who has lived on the east outlet of the creek for 10 years, said the bottom is normally dark and rocky, but it looks light and sandy now. She noticed the change the week of Sept. 9.
“It’s thick, and it’s shallow. At first I thought they had blocked it off (at the dam),” Davidson said. “It looks very sandy and milky.”
“I noticed the creek is filled up with sand. The water is a lot clearer,” said Orlyn Steffen, who lives within walking distance. “It’s usually dark water and a lot deeper. It’s usually up to your neck and now it’s waist high.”
Steffen said he has been fishing and spearing suckers in Cada's Creek for nearly 14 years. He said the creek normally has a gravelly bottom, with two sand bars to stand on for spearing into the deeper water.
“It’s all the way across,” Steffen said. “From bank to bank it’s full of sand.”
Upon closer inspection the sediment has a texture that is both gritty and slimy. It is not compact, and you cannot stand on it without sinking through.
Individuals from the DNR and Minnesota Pollution Control Agency declined to comment, saying they were not familiar with this creek, but John Ringle, director of Cass County Environmental Services, was willing to give information about how similar waterways might be impacted by sedimentation.
“More than likely it will settle out depending on how big an area it is,” Ringle said, noting that if the sediment is confined to a small area it will likely not have any real impact and it may even wash away in the spring when flow is strongest.
“I would say it’s probably got to be more than two to four inches thick before plants couldn’t make their way through it, and if it’s a fairly gravelly portion of the stream there’s probably not much there for plants,” Ringle said. “If we’re not talking dumptruck loads full, then it is probably of minimal impact. If we were talking many dump trucks, then it could be very serious.”
Ringle said stormwater runoff, erosion and sediments are more common on lakeshores, though they do happen in rivers as well. He said there is no way to be certain how this sediment will impact the ecology in this small section of river, but if the sediment does not wash out of the river it could change what fish and plants live there.
“It’s probably already started to be colonized by something whether it be microscopic algae. It’s just going to change the ecology a little bit. A lot if there’s a lot of sand. It’s dynamic. It’s continuously changing, so it may be neither good nor bad, but it’s a change,” Ringle said. “Mother Nature has a way of healing herself.”
“I hope it doesn’t hurt the spawning walleyes that come through there. That’s my only concern, really. It would kind of screw up a fun place to fish if the fish don’t migrate through there,” Steffen said. “Hopefully in the springtime in that heavy current a lot of that sand is going to get washed further downstream.”
Travis Grimler can be reached at firstname.lastname@example.org. Follow him on Facebook.