The mixed marshy terrain of the Conejohela Valley contained rapids and small waterfalls, wetlands, and thick woods along both sides of the river within a ten-year floodplain which saw annual inundations all the way down into Maryland at the headwaters of Chesapeake Bay, and experienced catastrophic floods regularly. The varied terrain created many interface zones biologically nurturing a great many species and many of those habitats effectively created difficult walking and horseback terrains which stifled east-west crossing of the lower Susquehanna in colonial Pennsylvania-Maryland spurring the 1730 opening of the historic Wright's Ferry and Columbia-Wrightsville Bridges, once believed to be the longest covered bridges in the world.
Siting
The dam is located just above the confluence of the Conestoga River with the Susquehanna, about 7 miles downstream of Washington Boro, Pennsylvania, which at mid-river is figured more or less the center of Lake Clarke created by the damwhich has become very popular for water sports and fishing. Ecologically the varying depth of inundated islands on the bottom of the lake create a succession of valuable varied habitats that support numerous fresh water feeder fish, pan fish, and large predatory game fish species and so loss in bird-small animal habitat was replaced by and large, in freshwater marine habitats.
Planning for the construction of the Safe Harbor dam started in 1929 and construction started 1 April 1930. The dam was completed and closed its gates for the first time on 29 September 1931. The first power was generated on 7 December 1931 and the last of the original seven turbine generator units came on-line on 14 October 1940. Expansion of the generation capacity started planning in 1981. Construction started 12 April 1982 and the 5 new turbine generator units came on-line between 13 April 1985 and 12 April 1986. Units 1 and 2 are Kaplan turbines connected to single-phase generators to produce 25 Hz single-phase electric power for railroad use by Amtrak and SEPTA, but also can be connected to a motor-generator to convert any spare 25 Hz power to 60 Hz. The rest of the units generate 60 Hz, three-phase, power. Safe Harbor can generate 417.5 megawatts of hydroelectric power. Power from Safe Harbor is dispatched through PJM Interconnection, one of many regional transmission organizations feeding the nations power grids.
Key events
On 18 May 2001, President George W. Bush visited the Safe Harbor Hydroelectric plant to expound on his just unveiled National Energy Policy. Safe Harbor was chosen as an example of government, corporate and environmental groups working together in energy generation. In 2001, Safe Harbor Water Power Corporation won the Governor's Award for Environmental Excellence. The award citation states that Safe Harbor had removed over 11,000 tons of debris from the river and was able to recycle almost all of it.
