Area of base x height
area of base = 9, 940, 000 m^2
height = 119 m^2
VOLUME = AREA OF BASE X HEIGHT = 1,182,860,000 m^3
Mass = 1 m^3 = 1000kg
Mass = 1,182,860,000 x 1000 = 1, 182, 860, 000, 000 kg of water in the lake.
if the wall broke and the water came out the valley would be completely destroyed and flooded, a Honda Civic is roughly 1000 kg, so imagine 1,182,860,000 Honda civics rolling your way. A elaphant is roughly 6000 kg so imagine 197000 elephants running at you. You have no chance.