The Wisconsin DNR is adding bright yellow-green dye to the Menasha lock canal.
The goal is to make sure the invasive round gobies can't bypass the lock to enter Lake Winnebago.
The DNR said the dye they're using is non-toxic. It's not harmful to fish or humans and it won't stain your boats.
The DNR is adding the dye to the water in the canal and the water below the Menasha dam apart of Little Lake Butte Des Morts.
They're trying to see if there are any cross connections such as old industrialized water pipes that would allow round gobies into Lake Winnebago water.
The DNR said the reason they're dyeing in this location is because nobody knows how many pipes there might be underground and whether they are sealed or not.
The DNR wants to keep the round goby from migrating upstream into the Lake Winnebago system.
"We really want to keep gobies out of Lake Winnebago system because they're a predator on fish eggs and they can really disrupt the ecology of the lake," said Water Resource Field Supervisor, Rob McLennan of the DNR.
The DNR will have staff on the ground and in a plane Thursday to monitor the dye.
A pilot will be looking down from above to see if any dye is coming out on the other side of the island.
The DNR said you could potentially see the bright color in the water through the holiday weekend.
It will dilute faster if there is more sun.
