Scary dream! Those are the type that I enjoy though. The adrenaline rushing, heart pounding, exciting.. I wake up from those thrilled and energetic. And it's nice that you can remember so many details. I remember a long time ago when my dreams were only two sentences long.
That's an interested way of depicting.
If you don't mind, I think I have an explanation for this dream - not saying it's 100% right- but, it could help. Water is sign for life and happiness. And, as you said, you were in a desert, meaning it' a harsh and difficult situation. And your small footprints turned into large lakes, right? In my point of view -which may be not true-, this dream means that your actions, which you would find it useless and small, could cause great benefit to people. Again, I may be Wrong. Allah a3lam.