Two photos of the transmitter cooling pond in operation. The transmitter's tubes were cooled with distilled water, which was pumped to a heat exchanger where it shed its heat to another water line .  This second water line went to this outdoor spray pond which cooled it in the ambient air. 

LEFT:  The spray pond as originally installed by General Electric in its contract to build the KPO facility, 1933.

RIGHT:  A later nighttime image of the spray pond, possibly 1940's.  In the foreground at left is the garage. The illuminated tower and the feed line supports belong to KGEI (G.E.'s adjoining shortwave station), and they came from the KGEI transmitter building out of sight to the right of this scene. The white structure halfway to the towers is an incinerator.