You have plenty of cooling water, but it might help to state the temperature of the cooling water on the outbound hot side.
150-300 tons? hmmm, odd to measure water in tons, but enough to know total heat is a lot, even at moderate temperature value.
And this must be a a large facility.
The more we know, the more it would help, you ask a very open question with little details.
Are you in some part of the country that requires lots of building heat at this facility?
Your best bet might be to create steam, and run steam pipes for steam heat, as has been done for decades at many large facilites. This is much more efficient than most people realize. And no rocket science required.