[alienasa]

One of the other things the new locks do is try to save water. The lake at the center of Panama is at a higher elevation than the ocean on either side - each time the locks are cycled water flows from the lake to the oceans.

The water in the lake is only refilled during Panama's rainy season, and drought conditions in recent years have on occasion made it necessary to put restrictions on the ships transiting the system.[1]

Those huge basins next to the new locks in the video are a water cycling system. They aim to capture a significant percentage of the water as they cycle the locks and then re-use it, rather than just draining the lakes.

[1] http://www.channelnewsasia.com/news/business/panama-canal-re...