Steller's Sea Cow was an
Arctic manatee

I can't imagine that our manatee is very closely related to any arctic species.
They get sick and die when the water gets much below 70f. Even in SW Fla the
bays and rivers cruise around 65-70f for 3-4 months a year, hence the power
plant connection.
Historically there may have been some hot spring connections but the strain on
the fresh water supplies have pretty much made springs a thing of the past.
(and sink holes a regular occurance) My 200' well used to free flow, now the
water level is below 30 feet in the winter.