Removal of the Orienta Hydro Dam and Construction of Fish and Lamprey Barrier

In September 1985, a significant rainfall occurred in northern Wisconsin near the town of Port Wing. The event was so large that a significant amount of trees and brush were washed downstream where this debris accumulated on the Orienta dam, including the tainter gate spillway. Once the operator reached this remote dam site, he found an enormous amount of debris in front of all the discharge features. The dam was soon overtopped, causing the left earthen embankment to fail. Feasibility studies were performed to evaluate redevelopment of the dam and the damaged powerhouse and generating facilities. These evaluations did not result in the site being redeveloped. In 1996, Northern States Power (Xcel Energy) applied for an abandonment permit with the Wisconsin DNR. After a series of meetings with the interested parties, resolution for the final removal and abandonment of the site was established in 2001.

Plans were developed for the total removal of the dam and construction of a new fish and lamprey barrier to restrict movement of fish and lamprey upstream to native trout waters. In order to coordinate the engineering and construction, Xcel partnered with the Wisconsin DNR to use one engineering firm and one contractor to complete the removal of the dam and construction of the barrier. Because the objectives of Xcel and the WI/DNR were similar, and they chose to work together on this project, both parties were pleased with the project results. This teamwork was critical to coordinated, timely completion of the project work, including smooth transition from dam operation, to dam removal, and operation of the fish and lamprey barrier.

Demolition and construction started in the fall of 2001 and was substantially complete within a few months. Explosives were used to remove the dam in 4' lifts. Construction of the barrier was completed before any fish or lampreys migrated into the waters upstream. The site has been restored to provide a more free flowing river that will provide many recreational opportunities. This could not have been accomplished so quickly and effectively without the coordination of the owner, regulators, engineer, and the contractor. 10 pp., 10 figures, 6 references.