You're correct. Estimates for an enlarged Panama Canal are that the new lake needed to supply the locks would have to be 4-5x time size of the present body of water. Who gets to write the environmental impact statement?
The bigger problem in Panama is the unstable soil...landslides occur constantly, dredging is continuous..and the new, proposed canal, besides being wider, would have to be much deeper..which makes the landslide problem much greater.
Huh? Where are you getting your information from?
There is no new lake.
Gatun Lake's level will rise by 1.5 feet. Additionally, the widening and deepening of Gatun Lake's and Gaillard Cut's navigational channels will add 385 million gallons of water capacity per day.
Suggest reading the ACP's plan.