Scott Rall: Fighting the good fight
If you are the area fisheries manager for the DNR located out of the Windom Area Fisheries office, you will have been asking yourself this one very important question over and over for the past two years and will continue to do so for the next decade for sure. The question is, “How do I think like an invasive Asian carp?”
Ryan Doorenbos has been tasked with the challenge of keeping these invasive fishes out of our watersheds ever since they were found in the Iowa Great Lakes a few years back. These invasive fish are only 30 miles from Worthington and just a few miles from the Minnesota border. Keeping them where they are and not allowing them to expand their current reach is a feat fit for a whole team of experts, and the job rests firmly in the lap of Ryan Doorenbos.
He called me last week and we went on a short tour of the projects that were recently completed under his leadership. The most important step in this containment effort is to identify all the spots where these fish could jump/swim from one watershed to another. If these invasive fish could find a way into the Des Moines watershed they could then spread not only north into the bottom third of the state of Minnesota but also back to the south into an area that covers the western third of the state of Iowa.
The first spot we went to was right in the middle of a mile stretch of gravel road. There was no water to be seen for more than a mile in any direction.
He identified this spot as a watershed breach between the Des Moines watershed and the Little Sioux River watershed. The spot was nothing more than a culvert surrounded by thousands of acres of corn and beans.
When the creek to the west overflows its banks, which is now does on an annual basis, the water flows over the land and once over a slight rise the water runs downhill in the road ditch and through a culvert into a different watershed where the invasive fish have already been found. I could not believe that this little nondescript spot was one of the biggest weak links in the containment of this terrible fish.
The DNR used a conservation easement with the land owner that allowed them to close the culvert and pond the water on this landowners’ crop field. By closing the culvert the water would be held in the current watershed, eliminating the stream flow that would allow the fish to swim over the crop land acres and into the next watershed. They had to raise the height of the gravel road about six inches to ensure that it would not top the road surface and allow the fish to swim over the road.
This road improvement was supposed to cover all the conditions up to a 100-year flood. It would take another 12 inches of additional height to cover a 500-year flood event. I told him that the 100-year flood event now happens about every five years so the extra 12 inches was an absolute must. A closed culvert and six inches on the road and this watershed breach was closed. This was not an overly expensive fix for this site.
The next site was a little different in that the amount of water flowing through this site was enormous. It would take an electric fish barrier at this site to complete the task.
This barrier is very expensive. The cost to install one is close to a half million dollars. One has to ask what the potential catastrophic consequences would be if these invasive fish reached the rest of the state, and the cost then seems much more reasonable.
It was the most technically advanced project I had ever seen. The six-foot tall culverts are made from fiberglass reinforced concrete unlike the steel re-bar bar ones used in a normal bridge. With electricity flowing over the bottom of the culvert there could be no steel there to interrupt the electrical current flow.
Located next to the bridge was a fenced in area. We entered and I saw a large stainless steel box about the size of four refrigerators standing side by side. Inside was a computer and all of the equipment needed to operate the electric fish barrier project.
The container was lined with Kevlar. Kevlar is what bullet-proof vests are made out of. This would keep the barrier operating in the event that some low life decided to shoot a bullet at it.
This invasive fish containment is very serious business. There is a back-up generator to keep the electric barrier operating in the event of a power disruption.
Components are in place to shut off the electrical current when there is no water flowing through the culvert. This system could tell when there was as little as three centimeters of water flow. There are air conditioners and heaters to keep all the electrical components within operation temperature tolerances.
All of these systems send a text message to the phone of the fisheries manager with constant updates. When the back-up generator starts up for thirty minutes each week it sends the report to the managers’ phone to let him know the systems is working perfectly.
Just imagine 1,000 fish trapped below the barrier and then suffering a 10-minute power failure. All of the money invested would have been totally wasted.
There is no room for error in this effort.
There were several other sites we looked at. On was the caged culvert designed to keep the carp from swimming up stream. It traps the fish behind the gate and still allows the water to pass. In this site there is not enough trash to plug up the gate, so the water can still flow.
The folks working on this project even went so far as to find every field tile that drained in to the affected watershed and followed them to where they started. Many of these tile allow the water to run right off the surface into a drain tile and then cross a watershed boundary. In this case the fish could swim up the pipe for a mile or more and exit into the surface water in a different watershed.
This requires that every surface intake be covered with what’s called a hickenbottom cap. This is a large orange cover that allows the water to get in but keeps the carp from swimming up the pipe to freedom.
There are hundreds of hours and hundreds of thousands of dollars being invested to keep these carp where they already are and no further. We viewed several other sites and what was the most surprising to me is just how many places there are that with little to no effort and one serious rain event these fish could move into thousands of square miles of additional watersheds almost overnight.
At a Lessard Sams Outdoor Heritage Council meeting on Tuesday of this week we moved about three million more dollars into this fight.
There should be another important barrier in place in our area within the next year. All we can do is use the best available science at the time to combat this issue. I hope that in the end we are successful. We really don’t know what our lakes and rivers will look like if these fish make it to all the places they really want to be. Those places are in every lake and stream in North America.
Good job Ryan, keep up the fight.