Loch Alsh Reservoir

About Loch Alsh Reservoir

The primary purpose of Loch Alsh Reservoir is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Borough Of Ambler (local government). It impounds the Tr Wissahickon Creek.

The dam stands 16 feet tall and stretches 513 feet across, creates a reservoir covering 6 acres, has a maximum storage capacity of 41 acre-feet, and collects water from a drainage area of 0 square miles. Completed in 1915, 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 satisfactory, indicating no existing or potential dam safety deficiencies are recognized. An emergency action plan is in place for this dam. The most recent inspection on record was 11/18/2020.

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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