If that's the configuration, why would they not be set up for a geothermal heat pump configuration where they could dump the water in a different end of the aquifier?
I understand that. That's a firm in Minnesota that builds geothermal heat pumps that use ground water year round. I should really look up the company so I can share the knowledge, but they're not dumping the aquifer into the storm drain.
Eventually any reservoir will become saturated and won't be able to store any more heat.
They're also very expensive. An evaporative cooling tower is cheap.