There are many serious questions about a recent oil spill that ended up in the water near Somerville.
Investigators say the impact could be far more reaching than just to wildlife and could take years to return back to normal.
Investigators with the Coast Guard drove Boston 25 News out to the exact source of the leak where contractors are in the process of putting on a permanent seal.
A pipe under I-93 leaked oil, which seeped into the soil, then into the storm drainage system and into the Mystic River about a half mile away.
It's still unknown exactly how much oil spilled.
"We know that it's been significant," said Derek Berkley, U.S. Coast Guard. "This is very concerning. It has a lot of public impact for boaters out in the water."
Investigators first noticed sheens of oil in early April and spent weeks trying to find the source. They tell Boston 25 News that it stems from Eversource using the oil to cool power cables. The company is now responsible for fixing and cleaning it up, and could even face fines.
"Eversource is responsible to fix the leak and to mitigate any of the damage that comes with that and the costs associated with both public and environmental damage. Enforcement actions will be considered at the conclusion based on their actions and the final impact," said Berkley.
The work to repair the leak could last another week, but cleaning up the oil could take weeks, months, if not years.
Boston 25 News reached out to Eversource Wednesday for comment:
"We're taking full responsibility for the mineral oil leak and we'll do whatever it takes to clean-up and restore the impacted environment."