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Stanford Report, March 11, 1998

The high cost of keeping dams safe: 3/11/98

$20 billion needed to ensure safety of nation’s dams, engineer estimates


A study released today significantly underestimates the price tag for maintaining the safety of the nation's 95,000 dams, a Stanford professor suggests.

In its 1998 report card on the nation's infrastructure, the American Society of Civil Engineers (ASCE) estimates that it will take $1 billion to rehabilitate the 2,100 dams that have been identified as unsafe.

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Fixing unsafe dams, however, is only part of the nation's dam safety problem, according to Martin McCann, consulting professor of civil and environmental engineering at Stanford and director of the National Performance of Dams Program (NPDP).

The real cost for effectively managing the risks that dams represent, so that people can continue to realize the benefits that they provide, is about $1 billion per year for the next 20 years, he says.

Cost factors not being considered include:

Another cost that is generally overlooked is dam failures, including fatalities and injuries; property damage; emergency operations and clean-up costs; loss of dam infrastructure and the revenue it generates, environmental impact, and economic impact on nearby communities.

Heavy rainfall created a breach in a Wisconsin dam in 1985, causing major damage to the powerhouse. Approximately two-thirds of all dam failures are caused by floods. According to Martin McCann, a consulting professor of civil and environmental engineering here and director of the National Performance of Dams Program, the cost of keeping the nation’s dams safe could exceed $1 billion annually for 20 years.

Northern States Power Company

The costs of dam failures can be significant. The 1976 failure of the Teton Dam resulted in damages of $900 million and 11 fatalities. The failure of Lawn Lake Dam, a small earth embankment, in July 1982 produced $35 million in damages and three fatalities. In 1996, the failure of a small dam in New Hampshire resulted in one death and $5.5 million in damages.

"There is no free lunch. Either we make the investments required to keep our nation's dams safe, or we will pay the price in dam failures," says McCann. By 2020, more than 85 percent of our dams will be more than 50 years old, generally considered to be the design life of a dam."

Dam infrastructure

More than 95 percent of the dams in the United States are privately owned and regulated by state dam safety agencies. Dams provide a range of benefits, including domestic water supply, hydroelectric power, flood protection, recreation, and agricultural and industrial water supply. However, dams also pose a substantial economic and societal risk. As a result, it is a national imperative that the risks associated with dams and their operation be understood and that the safety of dams be properly managed, McCann says.

Approximately two-thirds of all dam failures are caused by floods. The second leading cause of dam failure is excessive leakage and internal erosion, which accounts for 19 percent. After floods and seepage and piping, no single cause contributes greater than 4 percent to the total, and the majority range from 0.1 to 2 percent. Additional causes of failure include animal burrows; concrete deterioration; deterioration and failure of structures and equipment required to release excess water during floods or emergencies; earthquakes; embankment instability; foundation problems; ice pressure, settling; structural failure; and wave action.

Dam performance

Working with the Association of State Dam Safety Officials (ASDSO), the Federal Emergency Management Agency and other federal agencies, the National Performance of Dams Program (NPDP) has set up a process for gathering information on the performance of dams in the United States. Since the program officially began in September 1994, information on 1,814 dam incidents has been reported to the NPDP.

A dam incident is an event that involves the safety of a dam and provides insight into its structural and operational integrity. Incidents include the uncontrolled release of the reservoir downstream and safety-related findings such as excessive deterioration, excessive seepage, and damaged or inoperable outlet works.

Currently, the program is working with the ASDSO to make the process of reporting dam incidents an ongoing part of state dam safety practice. Based on current trends, it is estimated that as many as 1,000 safety-related dam incidents occur annually at the 95,000 dams regulated by the states.

The NPDP currently has on record 1,448 dam failures and more than 4,000 dam incidents that occurred in the United States in the past 150 years. Of these, at least 73 have resulted in fatalities, including 2,209 deaths from the 1889 Johnstown Flood and the failure of South Fork Dam. Since 1972, the year of the Buffalo Creek Dam failure that killed 125 people, there have been 724 known failures. In the last five years, there have 380 dam failures. Due to inconsistency in reporting practices that continue today, it is likely that the actual number of dam failures is greater.

NPDP, which is located at Stanford University, is working with national dam safety leaders to gather and evaluate information on the performance and safety of dams in the United States. Its objectives are to retrieve, archive and disseminate information on the performance of dams that will support efforts to improve dam safety, dam design and rehabilitation and the implementation of effective public policy. It is an integral part of the National Dam Safety Program that was signed into law in 1996. SR