In the sense of a large amount of something, lot is number transparent. In other words, it looks singular, but when it is the subject of a sentence, the verb should agree with the number of whatever is being talked about.
A lot of water is running. (water is singular, so choose is)
A lot of people are running. (people is plural, so choose are)
Lots of water is running. (water is singular, so choose is)
Lots of people are running. (people is plural, so choose are)