A cast-iron pipe 2.0 ft in diameter and 200 ft long joins two water (60°F) reservoirs. The upper reservoir has a water-surface elevation of 155 ft , and the lower on has a water-surface elevation of 45 ft. The pipe exits from the side of the upper reservoir at an elevation of 120 ft and enters the lower reservoir at an elevation of 25 ft. There are two wide-open gate valves in the pipe.