Allison Reservoir

About Allison Reservoir

The primary purpose of Allison Reservoir is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by O-ryan Development, Inc. (private). It impounds the Tr Dunlap Creek.

The dam stands 45 feet tall and stretches 348 feet across, creates a reservoir covering 14 acres, has a maximum storage capacity of 180 acre-feet, and collects water from a drainage area of 0 square miles. Completed in 1917, the structure is over a century old.

This dam carries a high hazard potential classification, which means that a failure or uncontrolled release of water would likely cause loss of human life. This classification reflects the consequences of failure, not the likelihood — it indicates that people live or work in the area downstream. Its condition is rated fair — the dam has minor deficiencies that are being addressed or do not pose an immediate safety threat. An emergency action plan is in place for this dam. The most recent inspection on record was 03/30/2021.

At 45 feet, this dam is taller than 91% of dams nationwide.

Living Downstream

If you live or work downstream of this dam, consider taking these steps: learn your local evacuation routes, check whether your county emergency management office has a dam failure inundation map, and sign up for local emergency alerts. The Pennsylvania dam safety program can provide more specific information about emergency planning for this structure.

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