On the north it is bordered by the watershed of an unnamed stream that flows down from between Breakneck Ridge and Sugarloaf Mountain to the north of that peak. The basin does not extend much to the northeast beyond the camp at Surprise Lake; there it gives way to that of Foundry Brook, which rises from Cold Spring's municipal reservoir almost a mile (1.6 km) away to drain into the Hudson just south of Cold Spring, bounding the Breakneck Brook watershed on the east and southeast in the process. A very small portion of the watershed on its south borders on the Hudson's direct drainage from the steep western slope of Bull Hill.