EDIT: To elaborate a bit, if you are burning oil or gas in a turbine, you do not need a cooling tower, the waste heat goes into the atmosphere with the exhaust. If you use fossil or nuclear fuels to produce steam for a steam turbine, you either need a river with enough flow to not boil all the fish if you reject the waste heat into it or you need a cooling tower to reject the heat into the atmosphere.
[1] https://en.wikipedia.org/wiki/Coal-fired_power_station#/medi...
EDIT: To elaborate a bit, if you are burning oil or gas in a turbine, you do not need a cooling tower, the waste heat goes into the atmosphere with the exhaust. If you use fossil or nuclear fuels to produce steam for a steam turbine, you either need a river with enough flow to not boil all the fish if you reject the waste heat into it or you need a cooling tower to reject the heat into the atmosphere.