A mysterious truck sitting at the bottom of Harvie Passage is still there weeks after the fire department's aquatic team first discovered it.

City officials don't know how long it's been there — or how it got there — but they do know removing it won't be easy.

"It's presenting a number of challenges," said Andy Hughes with the city's water services department.

"One is the location of the truck. It's just downstream of the Harvie Passage and that means the river flow is a little more turbulent than normal in that area. The location to the truck again is right in the middle of the river channel, it's not close to either of the banks."

Aquatic teams are also facing restricted river access because of fish spawning season.

The city has to protect fish habitats by observing "fish windows" set by the provincial government — time periods where work in the river would pose the least risk to fish eggs, juveniles and spawning adults.

The current fish window runs from July to September, so crews are running out of time to remove the truck.

It's not clear so far exactly how the truck ended up in the river but city officials have some rough ideas.

"We can only assume that it entered the river at some point and it got partially washed downstream," said Hughes.

"Another difficulty with the truck is that it's partly buried in the riverbed, so it's a little difficult to fully identify at this point."