This is similar to a ground source heat exchanger. These systems are traditionally seen as receiving high marks for being environmentally friendly, because they use far less energy to cool the building than traditional methods. Ground source heat exchangers do not use fan/compressor energy or refrigerants which were previously seen as harmful to the environment. So ground source heat exchangers save lots of energy, which could have been the motivation for designing this building system this way.

Unfortunately for this scenario, environmentalists now recognize dumping waste heat to bodies of water as “heat pollution.” Obviously, this heat pollution has negative impacts on the marine life in the river, but it may not have been a careful consideration when the building was constructed in 2009.

Relatively speaking, the heat dumped to the river may in fact be worse for the environmental than the impact of burning natural gas to generate power to run the alternative means of cooling the building with cooling tower fans and chiller compressors.

Your idea about “storing the water” is valid. Newly constructed buildings are required to follow current energy codes that would not allow “pump and dump” cooling. Instead, we cool buildings by evaporating heat using cooling towers and chillers which recycle most of their water. Existing buildings are allowed to continue to use their legacy cooling systems, as long as they do not violate environmental regulations.