This 100-foot Blaw-Knox tower may have been built as early as 1904. It is the only one of its type remaining in New Jersey and perhaps the entire United States. It features an inside stairway and still retains a section of its original vertical rung ladder on the upper section. Its standard 6'x6' cab still contained a dial telephone in 1998 but had no fire finder.

The tower is on private watershed land and is not open to the public. This immense structure is all but hidden in the mature forest growth in this otherwise heavily industrialized and residential area. It cannot be seen until driving up under the tree canopy to within a hundred feet of the base. The old observer house now a private residence still is nearby. At one time the Watershed had it's own 1926 Chevrolet brush-truck and employee fire crew housed nearby. Foresterd Roper studied European Forestry techniques abroad and managed the watershed as an early form of sustainable forestry.

Old Sentinel Tower was never used in conjunction with the State Network.