Holtwood Dam

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Holtwood Dam
Official name	Holtwood Hydroelectric Plant
Impounds	Susquehanna River
Creates	Lake Aldred
Locale	South central Pennsylvania, USA
Maintained by	PPL Corporation
Length	2,392 feet (729 m)
Height	55 feet (17 m)
Construction began	1905
Opening date	1910
Geographical Data
Coordinates	39°49′36″N, 76°20′10″W

Holtwood Dam (also Holtwood Hydroelectric Dam, Holtwood Hydroelectric Plant, McCalls Ferry Dam) is the oldest of three major dams built across the lower Susquehanna River, and the middle location of the three. Constructed as the McCalls Ferry Dam between 1905 and 1910 by the Pennsylvania Water & Power Company. The dam was renamed Holtwood in honor of two company executives^[1]. In 1955 PW&P merged with the current owner, Pennsylvania Power & Light (PPL).

The Holtwood Hydroelectric Plant produces 109 Megawatts of power, using 10 turbine driven generators. The dam consists of a main concrete dam, which is mostly one continuous spillway, with a power house at the eastern end. The water level is raised by wooden flash boards and inflatable dam sections^[2].

The western end of the dam has the original, and ineffective, fish ladder. In the mid 1990s, construction started on a fish lift. In January, 1996 the fish lift and dam were damaged by the severe 1996 flood. The fish lift was completed in time for the 1997 season^[3] and began lifting american shad and other migratory fish species.

The Kingsbury thrust bearing of Holtwood's Generator No. 5 is designated an International Historic Mechanical Engineering Landmark. Previously used roller bearings would last about 2 months under the generator's 220 ton load, but the Kingsbury bearing has has been in use since 1912^[4].

The impounded water, Lake Aldred, was originally dredged for anthracite coal silt, or fines, washed downstream from the coal mining regions of Pennsylvania. This coal was used in the adjacent Holtwood Steam Generator station. When Safe Harbor Dam was built upstream, its impoundment was then "mined" for coal as well. More efficient primary mining upstream reduced the availability of fines, and 1972 environmental laws made the dredging impractical, so coal was brought in by train^[4].

The area below the dam is popular with whitewater kayakers, with eleven named hydraulic features^[5]. PPL plans to expand the dam are being challenged by this group^[6].

[edit] See also

• List of dams and reservoirs of the Susquehanna River

[edit] External links

• PPL Holtwood Environmental Preserve
• Holtwood Dam Photo
• Holtwood Hydroelectric Plant Photo
• Maps and aerial photos Coordinates: 39.8270° -76.3354°
  • Street map from Google Maps or Yahoo! Maps
  • Topographic map from TopoZone
  • Aerial image or topographic map from TerraServer-USA
  • Satellite image from Google Maps or Microsoft Virtual Earth

[edit] References

1. ^ The Conestoga Area Historical Society - Martic Township. Retrieved on July 22, 2006.
2. ^ Lake Aldred Water Level to Drop for Holtwood Dam Maintenance. Retrieved on July 22, 2006.
3. ^ How Fish Lifts Work. Safe Harbor Water Power Corporation. Retrieved on July 22, 2006.
4. ^ ^{a b} The Kingsbury Bearing at Holtwood (PDF). The American Society of Mechanical Engineers. Retrieved on July 22, 2006.
5. ^ Laucks, Jeremy. Susquehanna Surf Guide (PDF). Retrieved on July 22, 2006.
6. ^ Colburn, Kevin. New Project Threatens Holtwood Playspots (PA). Retrieved on July 22, 2006.