Dam failure, though rare, can cause catastrophic destruction of property and lives. Repairing hazardous dams can help, but simply removing them can be a better, more cost-effective option with accompanying environmental benefits. Why, then, do so few dam owners and decisionmakers consider removal as an option?
The United States has an aging infrastructure problem. The country’s roads and bridges, drinking water and wastewater facilities, ports, levees, dams, and more are in need of upgrades and repairs. The American Society of Civil Engineers (ASCE) has given US dam infrastructure a D grade, noting that the number of dams in poor condition is on the rise. This grade for dams is even lower than the D+ that the organization gave US infrastructure as a whole in its 2017 “Infrastructure Report Card.” In 2019, the Association of State Dam Safety Officials (ASDSO) estimated that $66 billion is needed to repair all deficient dams in the United States.
A more affordable option could be to remove, rather than repair, the most hazardous dams—but dams continue to deteriorate in place across the United States.
Built to hold back and control the flow of water, dams are physical barriers across streams, rivers, and waterways. They vary in size and type, from small earthen embankments to high concrete structures, and serve a diverse set of functions that include flood protection, water storage, hydroelectric power production, irrigation, ponds for farm livestock and fire protection, and recreation. Unlike most other kinds of infrastructure, such as roads and bridges, the vast majority of dams are privately owned.
Most dams in the United States were built decades ago, and some are more than a century old. The average age of the 91,500 dams in the US Army Corps of Engineers’ National Inventory of Dams (NID), a database that includes relatively large (at least 25 feet tall) and “high-hazard” (posing a risk to human life if they fail) dams, is 57 years old.
The failure of two dams in Michigan in May 2020 illustrates what can happen in some situations when dam deficiencies go unaddressed. After five inches of rain in two days, on top of saturated ground from earlier rainfall, the Edenville Dam on the Tittabawassee River collapsed, sending torrents of floodwaters downstream and causing a second dam, the Sanford Dam, to also fail. The town of Midland, Michigan, and surrounding communities were inundated, and approximately 40,000 people evacuated. No one died in the event, but property damages totaled $175 million.
The Edenville Dam was a 54-foot-tall earthen dam used for hydropower production until September 2018, when its license was revoked by the Federal Energy Regulatory Commission (FERC). The owner of the Edenville Dam, Boyce Hydro Power LLC, had been ordered by FERC, which licenses and regulates all hydropower dams in the United States, to increase the dam’s spillway capacity in 2004. The company failed to comply.
Fourteen years later, after many additional problems had developed at the dam, FERC finally revoked the license, and Boyce Hydro Power stopped producing power. Nonetheless, the dam remained in the river. Regulatory authority was transferred from FERC to the state of Michigan’s Dam Safety Program. And this year, the dam failed.
Catastrophic dam failure of this type is rare. A 2018 report by Stanford University’s National Performance of Dams Program tallies 1,645 dam failures in the United States between 1848 and 2017, but most of these failures happen at dams much smaller than the Edenville Dam; thus, the failures cause less flooding and property damage. Climate change is expected to cause many regions of the United States to become wetter, however, and extreme precipitation events to happen more frequently. This change in weather conditions—in combination with aging dam infrastructure and population growth that increases the number of people at risk—has heightened concerns about potential dam failures.
Dams by the Numbers
Of the approximately 91,500 dams in the NID, 63 percent are privately owned. This includes dams like the Edenville and Sanford dams in Michigan, owned by power companies, along with scores of others owned by individual property owners, businesses, irrigation districts, country clubs, colleges and universities, and homeowners associations. The next-largest ownership group, accounting for 20 percent of dams, is local governments.
Dams have been erected all over the United States, but Texas has the most and Delaware the fewest, according to the NID. Relative to state land and water area, Connecticut has the most, with 57 dams per square mile. Three more New England states join Connecticut among the top six states in terms of number of dams relative to state size. The six states with the fewest dams are all in the West. Alaska has the fewest by far, relative to its size, followed by Arizona and New Mexico. The oldest dams are in New England, but old dams exist all across the United States. In six states—Maine, Vermont, Massachusetts, Colorado, South Dakota, and Montana—more than three-fourths of the dams are more than 50 years old.
Dams serve a wide variety of purposes. Hydropower dams make up only 2 percent of all dams in the NID. Across 13 dam purpose categories, recreation is the most common, accounting for 32 percent of all dams, followed by flood protection at 19 percent and fire protection at 12 percent. Figure 1 shows a map of the most common dam purpose in each state.
In the western states of Colorado, Idaho, Oregon, Utah, and Wyoming, where agriculture relies on irrigation, irrigation dams account for between 44 percent (Colorado) and 59 percent (Oregon) of all dams. One-third of the dams in California and nearly half of the dams in South Dakota primarily supply water, but only 6 percent of dams nationwide are in this category. Flood control dams make up 66 percent of dams in Nebraska and 48 percent in Oklahoma.
Recreation dams include those that create large reservoirs for flat water recreation such as boating and swimming—in a state park, for example—or small ponds that serve an aesthetic function in a community or business development. “Recreation” also can serve as a catch-all category for dams that no longer serve their original purpose, or the purpose has become unclear. This is another way in which dams differ from most other infrastructure: a large number are still in place, in varying states of repair and disrepair, built in the nineteenth and early twentieth century, and no longer serve a useful function.
Many early dams were built to provide power for textile mills, gristmills, steel plants, and other industrial activities. Over the years, the plants closed, but the dams stayed behind. The Whittenton Pond Dam on the Mill River about 40 miles south of Boston in Taunton, Massachusetts, highlights issues that can arise with these dams. The wooden dam, built in 1832, originally provided power for a mill complex, but over the years, the condition of the dam deteriorated. After several days of heavy rains in October 2005, the dam began to buckle and was on the verge of failure. Local officials evacuated downtown Taunton and called in the National Guard. The dam was eventually shored up, which prevented its failure, and it was removed several years later. The event was an eye-opener for Massachusetts state officials, who realized that thousands of similar dams existed all over the state. In 2014, Massachusetts launched the Dam and Seawall Repair or Removal Program, which has since provided $34 million in grants and loans for dam repairs and removals.
Removing an obsolete or deteriorating dam can often be a better option than repairing it. In many cases, removal is less costly than repair, and if the dam no longer provides services of sufficient value, spending money on repairs makes little sense.
Removing a dam can have many environmental benefits. Dam removal restores a river’s natural function, improving water quality and conditions for aquatic habitat by increasing flows and reducing water temperatures, and provides passage to and from the ocean for anadromous fish species such as salmon. Most dam removals on the West Coast have been motivated by the need to improve passage for salmon and steelhead trout, several populations of which are listed as threatened or endangered under the Endangered Species Act.
The removals have ranged from very small dams, such as the 81 dams removed from the Cleveland National Forest in Southern California, to large dams with removal costs in the tens of millions of dollars, such as the 106-foot-tall San Clemente Dam in California and the Elwha and Glines Canyon Dams in Washington. On the East Coast, removals of dams such as the Edwards Dam on the Kennebec River in Maine and the Embrey Dam on Virginia’s Rappahannock River have benefited oceangoing species such as American shad, alewife, blueback herring, and American eel (a catadromous species that lives in freshwater and returns to the ocean to breed).
Dam removal can help with this infrastructure problem [in the United States], and numerous success stories provide good examples.
Dam removal also can create new river recreation opportunities by providing unimpeded boat passage and restoring whitewater conditions. The removal of three dams on the Cuyahoga River in Ohio was motivated by concerns over water quality, but removing the dams actually spurred growth in the local outdoor recreation economy by producing Class 5 rapids in downtown Cuyahoga Falls. The final dam slated to come down on the Cuyahoga River, the 60-foot-tall Gorge Dam, is expected to reveal a buried 200-foot natural waterfall.
The removal of certain kinds of dams can improve river safety. Low-head (or “run-of-the-river”) dams, which lie across the width of a river or stream and typically form only a minimal reservoir, create underwater circulating hydraulics that have caused hundreds of drowning deaths. After six deaths in one summer at low-head dams in Iowa, the state launched the Water Trails and Low-head Dam Mitigation Program, which focuses on removing and reengineering low-head dams around the state while providing canoe and kayak trails to enhance river recreation.
Despite these success stories, as of January 2020, only an estimated 1,700 dams have been removed in the United States. Numbers are on the rise—nearly half of the removals have taken place in the last ten years—but are low relative to the total number of dams. Moreover, a mere five states account for half of all removals: Pennsylvania (343), California (173), Wisconsin (141), Michigan (94), and Ohio (82). Figure 2 shows dam removals by state in five-year increments from 1980 to 2020.
If removal often is less costly than repair, and river conditions improve when a dam goes away, then why don’t we see more removals? The answer lies in a combination of factors.
Limited Enforcement of Dam Regulations
Private dam owners, and even many government agencies, are unlikely to consider removing a dam unless they are faced with making costly repairs required by dam safety regulators. State dam safety programs vary in the stringency with which they enforce regulations, but in many states, enforcement relies mainly on voluntary compliance by dam owners. Rarely do state regulators impose financial penalties or take legal action against recalcitrant owners. Federal regulators may not always do better: FERC gave the Edenville Dam owner more than a decade to fix problems before revoking its hydropower license. And even then, the dam remained in the river.
Regulatory Focus on High-Hazard Dams
When enforcement is strict, efforts are directed at high-hazard dams—those that would lead to a probable loss of life should they fail. As a result, many other dams fall through the regulatory cracks. For instance, many smaller dams are exempt from regulations altogether, including most low-head dams, and dams that have “significant” or “low” hazard ratings are inspected less frequently and are required to meet less stringent regulatory standards. Yet many of these dams—especially if they have limited use and are in poor condition—are good candidates for removal.
Underfunded State Dam Safety Programs
Most state dam safety programs are woefully underfunded and understaffed. According to ASDSO, approximately $59 million nationally is spent on state dam safety programs each year. California’s budget is $20 million; thus, a single state accounts for almost one-third of national spending. The average for the remaining 48 states (Alabama does not have a state dam safety program) is a mere $805,000. The average number of full-time equivalent staff per state dam safety office, according to ASDSO, is 7.6 (excluding California, which has 77 full-time employees working on dam safety).
In states where advocacy groups have a sizable presence and work with state agencies, more dams have been removed. But advocacy for dam removal in the environmental community is diffuse and quite limited in many areas of the country. In some states, such as Pennsylvania, advocacy organizations are quite engaged and work with state agencies. In other states, their presence is minimal. In the West, strong advocacy surrounds fish passage and habitat, but removing a dam can mean the loss of valuable water rights. As a result, some advocacy groups tend to focus on other means of improving passage and habitat for salmon, steelhead, and other species; for example, by replacing road culverts. Many advocacy groups, including whitewater recreationists, focus attention on hydropower dams because FERC is required to consider the effects of those dams on the environment when relicensing. However, hydropower accounts for just a small number of dams nationwide.
High Costs and Inadequate Funding for Dam Removal
Given the general reluctance to make dam owners pay for the cost of removal, most removals rely on grant funding, which is quite limited. The Massachusetts Dam and Seawall Repair or Removal Program mentioned above is one of the few state programs that provides generous levels of grant funding. Wisconsin has had the longest-running grant program and ranks third among states in the number of removals. The federal government provides funding through a few programs, but most of the money is tied to fish passage and habitat—which often leads to a mismatch between dam removal needs and the type of funding available.
Lack of Coordination across State Agencies
State dam safety programs are variously housed in natural resource departments, or departments of the environment, or water resource management agencies (the latter of which are responsible for administering the complex systems of water rights in western states). The states that ensure dam removal gets the attention it deserves are those with a high level of cooperation across state agencies or across various programs within an agency. For example, when dam safety agency staff work together with program staff who manage fish habitat and conservation, river restoration, and other functions, the removal option is more likely to be considered in lieu of repair.
Although removing a dam from a river isn’t realistic in all cases—and many dams in the United States still provide valuable water storage, hydropower, recreation, and other benefits—thousands of aging dams all over the country are in disrepair and no longer provide valuable services. Dam removal can help with this infrastructure problem, and numerous success stories provide good examples.
In Oregon’s Rogue River, an old and crumbling irrigation diversion dam, the Savage Rapids Dam, was removed in 2009 after 15 years of controversy and heated debate. The removal led to a ripple effect: five more large dams and several smaller structures have now been removed, with several more in the works, ultimately opening up 400 miles of the Rogue River and its tributaries. In Lexington, Virginia, the Jordan’s Point Dam on the Maury River, built in 1890, was similarly controversial, with many local citizens opposed to removal based on the dam’s historical significance. But the dam no longer served its original purpose, was the site of a drowning death in 2006, and had been determined by the Virginia Dam Safety Program to be structurally unsound. Owned by the city of Lexington, which faced repair cost estimates as high as $3 million, the dam was removed in 2019.
Correcting the factors that sideline dam removal as an option—most importantly, the limited enforcement of dam safety regulations and inadequate funding for dam removals—will lead to even more success stories that can help preserve the environment, people, and property.
The William and Flora Hewlett Foundation and the August Heid Trust helped fund the research described in this article.