A February 2017 diesel fuel leak at a Metro Transit garage in Brooklyn Center led to a criminal probe and an extended environmental assessment, government officials said Thursday.

Hennepin County and state environmental officials said there is no threat to drinking water from the leak from a fuel dispenser at the Martin J. Ruter Garage at 6845 Shingle Creek Pkwy., where more than 160 buses are kept. But they're still exploring possible damage around the area as well as actions by Metro Transit based on the complaints of a whistleblower.

"This is a very interesting case; the allegations are widespread and they don't just deal with the environmental issue," said Mike Risse, Hennepin County's environmental compliance and enforcement manager. "I am not saying laws were violated. … It could very well be [Metro Transit] acted appropriately and under the law."

But he said, "The complainant is making a lot of allegations and it's not something I want to ignore."

The multilevel investigation started when Metro Transit reported the leak in February 2017 to the Minnesota Pollution Control Agency (MPCA). Metro Transit then brought in a consultant to investigate the cause and extent of the leak.

After an initial report in August 2017, the MPCA directed Metro Transit to do more testing on soil, install at least five water table monitoring wells, map the locations of all underground utilities within 500 feet of the leak, collect sewage samples, conduct vapor monitoring and install permanent sub-slab soil gas sampling points on the eastern edge of the building.

Metro Transit hired Minneapolis-based Braun Intertec for $100,000 to conduct additional tests and complete the second phase by the end of December 2018, according to documents sent to the MPCA.

Metro Transit spokesman Howie Padilla issued a statement saying the aim is to run a clean, environmentally responsible operation.

"We take any indications of impacts to our surroundings seriously, which is why we report any potential issues related to our operations and our environment to the Minnesota Pollution Control Agency," he wrote. "Like them, we want answers to any concerns and look forward to seeing whether there are any issues. If issues exist, we look forward to seeing what needs to be done to address them."

Walker Smith, MPCA spokesman, said the leak initially came from a diesel fuel pump and "no one really knows how long it was leaking for."

But Smith said Brooklyn Center has a municipal water supply and "there's no immediate threat to the drinking water supply, which would be our primary concern."

Smith also said there was nothing about the leak that merited public attention or concern, that it was one of more than 1,000 leaks reported annually to the state agency. He also said protocol was followed, which includes an initial incident report, a study and remediation when necessary, all paid for by the leaker.

Risse said the county looked into the initial leak complaint, deemed it a small problem and closed the complaint. After further conversation with the complainant, Risse said he reopened the case. "The bigger question is how did the contamination occur and did Metro Transit respond to it appropriately," he said.

Hennepin County Commissioner Mike Opat, who represents Brooklyn Center, said initially it appeared all was in order after the spill. But "county staff are now involved in a more expanded investigation to confirm the groundwater is safe and all precautions have been taken," he said.

Risse declined to specify what he was looking into nor did he set a deadline.

"The complainant has been concerned about this site for many years," he said.

Brooklyn Center City Manager Curt Boganey said he's following the investigation. "Until we get the results of the investigation, there's probably no reason to panic," he said.