| Ripogenus Gorge | |
|---|---|
 1870s view of Ripogenus Gorge | |
| Length | 10 miles (16 km) |
| Width | 700 feet (210 m) |
| Geography | |
| Location | Northeast Piscataquis,Piscataquis County,Maine, USA |
| Coordinates | 45°52′33″N69°09′00″W / 45.8759°N 69.15°W /45.8759; -69.15 |
| Rivers | West Branch Penobscot River |
 | |
Ripogenus Gorge is a rock-walled canyon formed inMaine where theWest Branch Penobscot River intersects the Caribou Lakeanticline.Ripogenus Falls controlled discharge fromRipogenus Lake untilRipogenus Dam was completed at the upstream end of the gorge in 1916. The dam forms ahydroelectricreservoir raising the level of Ripogenus Lake to include the upstreamChesuncook Lake, Caribou Lake, and Moose Pond. This reservoir is commonly referred to by the name of its largest included lake, Chesuncook. The gorge provides an unusual exposure ofMaine North Woods bedrock typically covered by saturatedglacial till. TheSilurianRipogenus Formation of weaklymetamorphosed shallow marinesiliciclastics andfossiliferous limestone,has been described from investigation of the gorge.[1]
Spruce forests along the west branch wereharvested through the 19th century with logs floated through the gorge tosawmills as far downstream asBangor, Maine.Log driving rivermen altered the gorge withdynamite and timber cribs filled with stone to preventlog jams. Construction of Ripogenus Dam began in 1915 to provide hydroelectricity for thepaper mill atMillinocket, Maine. The dam is 92 feet (28 m) high and 704 feet (215 m) long and impounds the largest storage reservoir ever built with private funding.Hydroelectricity is generated by diverting 2,400 cu ft/s (68 m3/s) through a mile-longpenstock around the former falls.Pulpwood was sluiced over the dam until 1971 whenGreat Northern Paper Company began trucking the lumber to the mill via theGolden Road.[2]
Penstock releases through the gorge create a popularwhitewater run through class IVrapids with a class IV+boulder garden.Rafts andkayaks navigate between rock cliffs through colorfully named Exterminator Hole (IV), Staircase (IV), Fist of God, Big Heater, Little Heater, Troublemaker Hole (III+), Cribworks (V), Turkey Chute, Final Chute, Postage Stamp Rock, and Bonecruncher (III).[3]
