Mill

About Mill

The primary purpose of Mill is grade stabilization. Grade stabilization dams prevent erosion by reducing the slope and velocity of water flowing through a channel. They're commonly used to stop gullies from deepening and to protect downstream land and infrastructure. The dam is owned by P.h. Glatfelter Company (private). It impounds the Codorus Creek.

The dam stands 18 feet tall and stretches 250 feet across, creates a reservoir covering 23 acres, has a maximum storage capacity of 589 acre-feet, and collects water from a drainage area of 73 square miles. Completed in 1863, the structure is one of the older dams in the region, with over a century and a half of service.

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 12/30/2020.

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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