[The 210' concrete curtain of Glines Canyon Dam, Washington. Images of the dam's current state and rendering of post-dam removal (National Park Service). View an animation of the removal process here. Additional simulations and flythroughs here]
After 25 years of negotiation and preparation, the largest U.S. (planned) dam removal project got underway in September of 2010. The project entails the demolition of the Glines Canyon and Elwha Dams to facilitate the regeneration of the Elwha River system.
[Elwha removal process. Source]
Other large, and long-standing dams are pending removal, such as Condit Dam and four others on the Klamath River running between Oregon and California. Most of these dams were constructed before the idea of fish passage or ladders occurred to anyone. Thus the infrastructure largely put an end to salmon and other anadromous fish migrations, which in turn stopped a migratory process of massive annual nutrient and energy exchange in the broader environment. The cascading effects of these arrested processes have manifest over the past century.
The attenuation of fish migrations led to manufactured variants. In somewhat Sisyphean fashion, we resuscitated the migrations through a network of fish hatcheries and customized transportation logistics.
The peculiar mass fecundity of fish hatcheries currently contributes to between 70-80% of the fish in coastal salmon and steelhead fisheries in the Pacific Northwest,with mixed results; a manufactured landscape on life support.
[Glines Canyon Dam: Historical and current. Source]
As dams such as these are pulled out, the hope is that former self-sustaining fish migrations will regenerate, and in turn require less fish hatcheries. Examples thus far are demonstrating robust and promising results. The dam removal projects themselves are fascinating, requiring heavy-duty de-engineering techniques; the temporal gymnastics of restoration science in a radically altered terrain; figuring out how to best ‘manage’ all the sediment trapped behind the wall of the dam; assessing widely varying public perceptions regarding dam removal and post dam recreation opportunities; and engaging the thick political, corporate, and bureaucratic ecologies surrounding the whole thing (can you tell we worked on one).
When an active hydroelectric dam goes offline, we assume some other landscape must come on, as energy demand is only increasing. Sort of like a cultural geography rendering of the law of energy conservation, in which energy formerly harvested from one place must now be sought elsewhere, such as the forthcoming world’s largest wind farm. Infrastructure migrates away from one landscape to morph and reappear somewhere else.