Facility Description Enloe Dam and Hydroelectric Power Plant, Oroville Washington
Located in north central Washington a few miles south of the Canadian border, Enloe Dam and Powerhouse are situated in a narrow constriction of the Simiikameen River Valley. From the deep gorge cut by the river, steep hills covered with rock and sagebrush obscure views of the nearby mountains in the Okanogan Highlands to the east and North Cascades to the west. Below the dam the Simiikameen River tumbles noisily over what remains of Simiikameen Falls; above the dam the impounded river appears motionless over its approximately three-mile-long pool.
Winding steeply downhill from the paved highway above, a rough dirt road provides access to the east bank of the river. On a terrace northeast of the east dam abutment are trees planted in rows where once stood houses occupied by operators of the hydroelectric facility. Stone walls and concrete foundations are all that remain of the razed structures. Downstream below the dam is the intake channel that diverted water to the original powerhouse predating the existing plant. Concrete foundation remains mark the location of the earlier building. Further downstream directly across the river from the existing powerhouse is a steel tower that once anchored a wooden footbridge by which operators reached their workplace from the houses upstream.
The dam itself is a concrete arch-gravity structure containing over 9,700 cubic feet of concrete. Its arching spillway stands approximately 54 feet above the stream bed, where its base width is over 41 feet. At the top of the 276-foot-long crest, the concrete is about 6 feet in width. Upstream the face of the structure is vertical, while the opposite face of the spillway is inclined downstream, with a 20 degree arc at its foot. Wooden flashboards once restrained the now- unregulated flow over the spillway. Metal pipes 6 inches in diameter embedded 1-foot deep in the concrete abutments anchored the flashboards, which were capable of raising the pool level 5 feet behind the dam.
Atop the right (west) abutment are hoisting devices controlling the sluice gates that provide water to the penstocks. The devices are installed at the downstream end of intake bays and consist of heavy metal gears and threaded stems mounted on concrete footings. The tapered metal housing around the vertical threaded riser stems is stamped with the name of the manufacturer, CD. Butchart Company of Denver, Colorado. A metal cabinet containing unspecified equipment stands behind the hoisting machinery. Open to the elements, the unroofed area containing the machinery is enclosed on the downstream and river bank sides by concrete walls standing about 3.5 feet high.
Stamped into the downstream-facing wall on the west abutment is the inscription "Enloe Dam 1920," commemorating the official name of the facility and its date of completion. Below the inscription at the foot of the abutment are steel outlet pipes 7 feet in diameter extending 8 feet outward from the concrete. Sluice gates 6 feet in diameter, manufactured by the Butchart Company, are seated in the abutment behind the pipes. At one time, two 7-foot-diameter wood stave penstocks were connected to the pipes. (One of the penstocks has since been removed). Mounted on timber supports, in places atop riprap fill, the remaining penstock extends 743 feet downstream to two elevated surge tanks. Designed to absorb surges of water through the system, the metal tanks stand directly above the penstocks to heights of 32 and 25 feet, with the taller tank being 17 feet in diameter and the smaller 24.5 feet.
Steel penstocks drop from the surge tanks into Pelton turbines installed in the Powerhouse, a structure occupying a narrow ledge carved from solid rock cliffs on the west bank of the river. Measuring 83 by 40 feet, the building consists of red brick walls standing atop a concrete foundation, topped by a gabled corrugated metal roof over the generating room. (That portion of the roof was removable for access to the turbine-generator units). A flat concrete roof is above the transformer room in the southwest corner of the structure, and a sloping tar roof covers the storeroom and shop in the southeast corner.
The largest space in the Powerhouse is the generating room, in which are the two Pelton 1600 kW turbine-generator units. Mounted horizontally the units are aligned parallel to the river. Below the floor, tapered draft tubes provide outlets for water passing through the turbines back into the river via an arched recess under the building. Two smaller exciter generators are attached to the turbine shafts. Units functioning as governors operated wicket gates at the upstream ends of the turbines. Mounted on an I-beam above one of the turbine-generators is a movable crane, consisting of metal plates suspended from wheels running on the inner ridges of the beam. Tall metal, hinged windows light and ventilate the room, which is 41 feet high. The room has been vandalized, and there is standing pools of water on the concrete floor.
A metal walkway and stairs connect the generating room with the switchboard room immediately to the south. Raised about 5 feet above the floor of the generating room, the smaller room contained electrical switch gear. Today only metal racks remain. Thirty-seven metal pipes, some containing conductor cable, protrude from the concrete floor near the north end of the room. Wooden 2x4 inch studs mark what was the partition separating the switchboard room from the storeroom and shop to the south. The room is now empty and the walls vandalized.
Accessed either from the generating room or via a wide, sliding metal door on the Powerhouse's west facade is the transformer room. Large free-standing electrical transformers were once installed in the room, which now contains only wooden and metal equipment and bus racks, and three small Westinghouse type S single phase 10 kV transformers mounted on the west wall. Because of the explosive potential of transformers, the room was stoutly constructed, capped by a concrete ceiling. The sliding metal door, which now lays on the concrete floor, is of extremely heavy construction.
Outside the transformer room and shop, a concrete deck extends into the rock cliff south of the Powerhouse. The deck once served as an outdoor switchyard in which electrical transmission equipment was installed. Some of the equipment, which has since been removed, was mounted on large concrete pads still standing on the deck.
