The investigation is expected to be complete at some point next year.
The Oulu Police Department has opened a preliminary investigation into the activities at Google's data centre construction site in Muhos, following a request from the Finnish Supervisory Agency to look into the matter.
The department has received five requests for an investigation related to the Muhos site, all of which will be addressed in the preliminary probe.
The data centre construction work is part of the tech giant's 13 billion euro investment in Finland.
Police said the matter is being investigated under the criminal heading of suspected environmental damage. They noted that other possible charges may be clarified as the preliminary investigation proceeds.
Police said that, based on current information, there have been irregularities and shortcomings in drainage and water management at the data centre project's worksite, which is run by Google's local subsidiary Tuike Finland.
The preliminary investigation is expected to take a good deal of time, police said, adding that efforts will be made to complete the probe during 2027.
The department said that it will aim to provide more information about the matter in December.
In a press release issued last week, the Finnish Supervisory Agency explained that it ordered Tuike Finland to halt construction work on two data centre projects — in Muhos and Kajaani-Otanmäki — because required environmental impact assessments for both projects remained incomplete.
The company complied, confirming on 14 October that preparatory work had been suspended at both sites.
Among other issues, the authority found Tuike Finland's water management plans insufficient to prove that water-related environmental impacts can be properly controlled.
It said the firm needs to submit a detailed water management plan by 5 November, including planned structures, timelines and independent water monitoring, accounting for heavy rainfall, snowmelt, and risks from acidic black shale soils in the area.
The authority noted that if adequate action is not taken, it may pursue formal enforcement measures, including a conditional fine.