Olympic National Park - Removal of the Elwha Dam (U.S. National Park Service)

A view of the Elwha dam from downstream, holding back Lake Aldwell

Dam Removal Strategy:

The first step in removing the Elwha dam will be to lower the reservoir's water level by using the existing water intakes and spillways approximately 15 feet.
A temporary diversion channel will then be excavated through the left spillway to allow Lake Aldwell to be further drained.
Coffer dams -- temporary structures acting as dams -- will then be installed to direct reservoir outflow into the temporary diversion channel.
This will allow the remaining water immediately behind the concrete dam to be pumped out and the fill material behind the dam to be removed under dry conditions.
The concrete dam can then be removed and the original river channel restored.
The powerhouse and all other structures will be removed and the temporary diversion channel will be refilled.
Finally, the site will be re-contoured and revegetated to most closely resemble the pre-dam condition.

This webpage was made possible in part by a grant from Washington’s National Park Fund.

You are exiting the National Park Service website