Questions about dam removal

Why are some dams being removed?


There has been a growing movement to remove dams where the costs – including environmental, safety, and socio-cultural impacts – outweigh the benefits – including hydropower, flood control, irrigation, or recreation – or where the dam no longer serves any useful purpose. The goal of removal can be multi-faceted, including restoring flows for fish and wildlife, reinstating the natural sediment and nutrient flow, eliminating safety risks, restoring opportunities for recreation, and saving taxpayer money.


How are dams removed?


Because dams and rivers vary greatly, physical removal strategies and techniques may also vary on a case by case basis. Here is more in-depth information on how dams are removed. How many dams have been removed to date? Currently, American Rivers is aware of almost 1,150 dams that have been removed over the past 100 years in this country. We are still in the process of gathering this data, so that figure continues to increase as more information becomes available. You can view an interactive map of all known U.S. dam removals.


Who owns the dams that are being removed?


Private businesses, federal agencies, state agencies, local governments, or public utilities may own dams. Most of the dams removed to date have been owned privately, by local government, or by public utilities.


Who pays for dam removal?


Who pays for the removal of a dam is often a complex issue. In past cases, removal has been financed by the dam owner, local, state and federal governments, and in some cases agreements whereby multiple stakeholders contribute to cover the costs.


Who decides that dams should be removed?


The decision to remove a dam is made by varying entities, depending on the regulatory oversight of the dam. In most cases, the dam owner itself is the decision-maker, often deciding that the costs of continuing to operate and maintain the dam are more than removing the dam. State dam safety offices can often order a dam to be removed if there are major safety concerns. State fish and wildlife offices are also often involved in the decision-making, particularly when the goals of the project include restoration of habitat for migratory and resident aquatic species. It the dam in question is a hydropower facility, the Federal Energy Regulatory Commission can order a hydropower dam under their jurisdiction to be removed for both environmental and safety reasons.


Can rivers be restored through dam removal?


Although most rivers cannot be completely restored to historic conditions – simply because of the amount of development that has occurred on and along them – dam removal can often recreate conditions that move the river towards those historic conditions. For example, fish are returning to historic stretches of river that had been previously obstructed on Butte Creek in California, the Souadabscook River in Maine, and the Clearwater River in Idaho, as a result of dam removals. What benefits do dams provide? Dams may provide a variety of benefits, including water supply, power generation, flood control, recreation, and irrigation.


How can the benefits of a dam be replaced when it is removed?


While dams serve a number of human needs, society has developed ways to address many of these needs without dams. For instance, flood control can often be accomplished more effectively and for less money by restoring wetlands, maintaining riparian buffers, or moving people out of the floodplain. Updating antiquated irrigation systems and replacing inappropriate crops can dramatically reduce the need for dams and reservoirs in the arid West. Rather than plugging rivers with multiple hydropower dams, a cheaper and less environmentally harmful solution is to use existing energy efficiency technologies. For example, the 3MW of power lost in the removal of the Edwards Dam, on the Kennebec River in Maine, can be replaced simply by replacing 75,000 light bulbs with energy efficient bulbs. Many dams that have been removed no longer had any beneficial use or that use was very limited.


Is it cost effective to remove a dam?


Dam removal can be expensive in the short term, but in most cases where dams have been removed or are being considered for removal, money is actually saved over the long term. Removal eliminates the expenses associated with maintenance and safety repairs, as well as direct and indirect expenses associated with fish and wildlife protection (e.g. fish ladders and mitigation for fish mortality). In addition, removal often generates income from newly available recreation opportunities – including fishing, kayaking, and rafting – which may actually result in a net economic benefit. In some areas, dam removal may allow resumption of commercial fishing activities.


Will the removal of a dam matter if other dams in the system are not removed?


Some rivers are so heavily developed and dammed that removal of one dam on that river will only return flows to a small portion of the river. Generally, dams that have been targeted for removal are strategically located – removal will open up a section of the river critical to fish and wildlife and/or recreation. In some cases, this additional section of river is enough to sustain crucial populations of endangered or threatened species of fish, mollusks, and other wildlife.


How does dam removal affect fish?


Dam removal benefits fish in many ways, including: (1) removing obstructions to upstream and downstream migration; (2) restoring natural riverine habitat; (3) restoring natural seasonal flow variations; (4) eliminating siltation of spawning and feeding habitat above the dam; (5) allowing debris, small rocks and nutrients to pass below the dam, creating healthy habitat; (6) eliminating unnatural temperature variations below the dam; and (7) removing turbines that kill fish.


How quickly do rivers recover after dam removal?


Rivers are very dynamic and resilient systems. Experience has shown that natural river systems can be restored relatively rapidly after dam removal. For example, spawning fish returned to the Souadabscook River in Maine only months after a dam was removed, and the flushing of the sediment from the Milwaukee River in Wisconsin following the Woolen Mills Dam removal took only six months. -