A co-operative rainbow trout tagging program on Portage Creek, near Sleeping Giant Park, has been put on hold due to high water.
The study began in 1991 to monitor the changes in the Steelhead population of the Lake Superior tributary.
Volunteers catch the fish on their spawning run. They are then tagged before being released.
The project manager of the study said it's been nearly impossible to get fish from the swollen river.
A large amount of rain over the past weekend caused the creek to flood. This followed the later than usual spring that delayed the spawn. However, Jon George says the study can continue.
"Even if we don't get them on the way up, we'll get them on the way back and get an estimate," George said.
"It's kind of frustrating when it's this late."
In a normal spring, George said they usually have tagged about 200 trout by now.
This year, they have tagged just 14.