The damming of streams and rivers has its roots in early human civilization. From the earliest settlements, humans have diverted and stored water for a variety of uses. Today, there are more than 85,000 dams in the United States, serving a variety of functions, including flood prevention, water diversion and recreation. Dams play a significant role in the nation's water supply and many large urban areas are supplied with water blocked by dams. Hydroelectric power from dams provides approximately 7 percent of electricity in the United States. About two-thirds of all dams are privately owned, and state and local governments own most of the remainder.
Although in the past dams were viewed as being almost entirely beneficial, today’s view of dams is more balanced, recognizing both the positive and negative effects. Impounding and diverting water for upstream users modifies local habitats, affects plants and animals, and influences the lives of those who live downstream. Dams can also present safety and economic risks due to the possibility of dam failure. While the risks associated with aging dams are typically of low probability, the consequences are high. Although dam failures are infrequent, the risk of failure increases with the age of the dam.
The first half of the twentieth century was the heyday of dam construction in the United States, peaking in the 1960s and decreasing significantly in the second half of the twentieth century and beginning of the twenty-first. This means that America’s dams are aging. The average age of a dam in the United States is more than 50 years old, and a small but significant number are a century old or more. Many older dams no longer function as originally intended. The dam structures may be in a state of disrepair, or the reservoirs created by the dams may have naturally filled in with sediment.
Currently, tens of thousands of dams are aging beyond their expected lifespans, with the possibility of attendant safety, environmental, and other problems. Managing aging dams is quickly becoming a principal focus of dam engineering, made more challenging by the fact that existing dams represent different generations of design standards and construction practices.
Nationally, the number of high-risk dams is increasing. In its Report Card for America’s Infrastructure, the American Society of Civil Engineers gave the nation’s dams a D grade. It would cost an estimated $16 billion to repair the country’s most critical dams, and additional funding is needed for inspections and enforcement of safety programs. Lack of funding for dam repair is a significant problem, particularly for privately owned dams. The responsibility for dam upkeep and repair lies largely with the owners, many of whom cannot afford the costs. Obtaining funding assistance, whether through government or private sources, can be difficult.
Dealing with these situations can be a costly and controversial, making dam removal an increasingly viable option. Not all dams are candidates for removal, since they may continue to provide important benefits or removal could have adverse impacts. Nonetheless, when appropriate, dam removal can provide significant benefits.
The environmental benefits of dam removal include restoring natural river flows, removing blockages for fish migration, re-establishing the river habitat for fish and wildlife, and improving water quality. Restoring a river’s natural flow through dam removal also aids in increasing biodiversity through the restoration of vegetation and habitats. Dam removal enables fish to migrate freely upstream and downstream, improving their chances for successful reproduction. Dam removal can revitalize wetlands, which serve as nurseries for aquatic species, and can enhance plant growth along riverbanks that provide shelter and food for wildlife. Dam removal can also help the local community by offering increased opportunities for recreation and tourism related to the restored river.
While removal of some dams is straightforward and relatively inexpensive, for many dams, removal can be complicated. Dam removal involves assessment of the dam’s uses, sedimentation, structural quality, and steps for restoring the river. Dam removal usually also requires multiple regulatory permits, environmental review, and numerous safety precautions. The process of physical removal can vary because of the unique aspects of many dams and rivers. Usually it involves drawing down the reservoir through notching or other methods, excavating sediment or letting it flow downstream, removing the dam structure, and reshaping and reestablishing the riverbanks.
Despite the challenges involved, dam removal is on the rise, as evidenced by several recent high-profile projects. In October 2011, removal of the dam on Washington’s Elwha River began. This project, which is the largest dam removal project in United States history, was originally anticipated to take two or three years. Removal proceeded quickly, however, and the Elwha Dam was completely gone by spring 2012. Also in Washington, removal of the Condit Dam on the White Salmon River is expected to be completed by this fall. Removal of the Great Works Dam on the Penobscot River in Maine began June 2012. The same month, the California Public Utilities Commission approved a project to remove a nearly 100-year-old dam on the Carmel River. Although a safety notice for the dam was issued in the early 1990s, it took several decades to develop a solution that was feasible from an engineering, financial, and environmental standpoint. This dam removal project, which is a joint effort between a privately-owned water utility and federal and state agencies, demonstrates the challenges – and benefits – of dam removal.
As the nation’s dam continue to age, hundreds of communities across the country are struggling with decisions about how to deal with the cost to operate, maintain and repair these structures. For some, dam removal can be the most prudent choice by eliminating safety hazards, restoring the environment, and revitalizing the community.
Lori Anne Dolqueist is a Partner with law firm Manatt, Phelps & Phillips, LLP in San Francisco and focuses her practice on utility regulatory issues, particularly in matters involving water utilities. She has represented numerous regulated utilities, as well as other interested entities, in a variety of regulatory matters. Ms. Dolqueist can be reached at (415) 291-7452 or ldolqueist@manatt.com. This column is part of a series of articles by law firm Manatt, Phelps & Phillips, LLP’s Energy, Environment & Natural Resources practice. Earlier columns have discussed Sustainable/Energy Retrofits of Commercial Buildings, Demand-Response and Energy Efficiency Programs, California’s Cap and Trade Program, Demise of Redevelopment in California, What's Next for the Renewable Power Industry and Renewable Energy Projects On Tribal Lands.
