Drain is maybe not the right word for Spruce Run Res. It is a water supply reservoir that gets low over the course of the year until the spring rains replenish it (hopefully). It is part of the same water supply system as Round Valley. However, Spruce Run fills naturally from the tributaries while the water in Round Valley is pumped up from the South Branch, which costs big bucks. Therefore, the NJ Water Supply Authority uses up the Spruce Run water before they start to draw water from Round Valley. For probably the first 40 years of Round Valley it never really was drawn down much. But the drought in the early 2000's caused the Round Valley level to drop quite a bit as well.