blockage in the toilet itself...where it cant be seen. Sometime, wires from toilet deodorizers, tampons, kids toys, etc. get hung in the pathways of the toilet itself. It then blocks waterflow...but cant be seen. A special tool, a toilet auger, can be used to carefully pull out, or push thru any blockage. good luck
Does Lake Mead go through any cities?
Lake Mead is a reservoir near Las Vegas. It doesn't run anywhere.
Water volume of 35.2 km3 (28,500,000 acre·ft)-----
28.5 million acre-feet x 43,560 square feet in an acre = 1.24 trillion cubic feet x 8.1 (gallons in a cubic foot) = 10 trillion gallons