Q: In this task, you are given a paragraph, and your task is to construct a question from the given passage. Construct question in such a way that (i) it is well explained in the paragraph, (ii) the words may/may not be present in the paragraph, (iii) it should start with what/how/describe. Avoid creating a question that (i) is just relevant to one or two sentences, and (ii) not relevant to passage. 
Waters flows downwards thanks to gravity. Enters the dam at high pressure. The moving water spins the turbines in the power plant. The turbines turn the generators. The generators spin, and produce electricity. The water leaves the dam at the bottom. 
A:
How is hydroelectric electricity generated?