A lake with no outlet is fed by a river with a constant flow of 1800 ft3 /s. Water evaporates from the surface at a constant rate of 12 ft3 /s per square mile surface area. The area varies with depth...

A lake with no outlet is fed by a river with a constant flow of 1800 ft³
/s. Water evaporates from the surface at a constant rate of 12 ft³
/s per square mile surface area. The area varies with depth h (feet) as A (square miles) = 4.5 + 5.5h. What is the equilibrium depth of the lake? Below what river discharge will the lake dry up?