The combined influence of the New York City water supply system's Croton Watershed, which includes most of the bodies of water along this stretch of US 6, and affluent residents who build on very large lots, keeps this area lightly developed. Leaving Mahopac, US 6 curves past the south end of West Branch Reservoir and controlled Lake Gleneida to its next highway junction, the east end of NY 52 at Reed Memorial Library just south of the county seat, Carmel. The highway immediately turns toward the south again, curving around Middle Branch Reservoir at Tilly Foster to the west terminus of NY 312. At this junction, signs for the Southeast station on the Harlem Line of the Metro-North Railroad are a reminder that this is still commuter country. Also appearing are the first signs for I-84, whose interchange with NY 312 is a short distance away, since Middletown.