Regina city crews have been at the scene of an oil spill since Monday which occurred on Sunday in the north area of the city.
Officials say about one-thousand litres of used engine oil was leaked from a tank owned by a local business.
Regina Fire and Protective Services, along with Environmental Services, contained the spill preventing it from entering Wascana Creek.
The oil spilled onto a paved back alley with an unknown volume going into the storm sewer system.
Cleanup activities continue as the nature of the spill remains under investigation.
The city is working with both the provincial ministry of the Environment and Environment Canada.