Changing perceptions of levees

December 2006 » Feature Articles
Following the failures of levees in New Orleans last year, professionals and lawmakers are looking at these flood-control structures in a new light.
Sarah Mayfield

Following the failures of levees in New Orleans last year, professionals and lawmakers are looking at these flood-control structures in a new light.

Although its full impact on the future mission of state dam safety programs remains to be seen, Hurricane Katrina caused a transformation in the collective conscience and mindset of the dam safety profession.

For example, not long ago, the Association of State Dam Safety Officials (ASDSO)—a national professional organization composed of more than 2,400 state and federal dam safety regulators, dam owners and operators, engineering consultants, manufacturers and suppliers, academia, contractors, and others interested in dam safety—was not paying much attention to levees. A few state dam safety programs had some regulatory control over levees, but most did not have the resources to regulate their safety adequately. Furthermore, the National Dam Safety Act specifically excluded levees; thus leaders within the dam safety community had had little discussion about how to deal with or define levees on a national level prior to August 2005.

About that time, ASDSO staff members were working feverishly on final preparations for their signature event, Dam Safety 2005, to be held Sept. 25-29 in New Orleans. ASDSO and Katrina were about to converge.

When the levees broke, ASDSO found an alternate venue in Orlando, Fla., and made adjustments to the technical program, including appropriately devoting the opening session to the levee failures in New Orleans and the wider relationship between dam safety and levee safety. In fact, Hurricane Katrina pervaded the entire conference and prompted future changes.

Just as the events of Sept. 11, 2001, forced ASDSO to broaden its focus to include dam security, the failure of levees in New Orleans was a benchmark event for ASDSO. Suddenly, levee safety loomed large in the association’s planning discussions and strategic goals. As part of its new initiative, ASDSO researched dam safety professionals’ perceptions of levees, and how they have changed during the past five years. Its findings are presented here, along with information about a proposed National Levee Safety bill and more.

Pre- and post-Katrina perceptions

At the September 2001 ASDSO annual conference, Alton P. Davis, Jr., and William F. Kennedy, who presented a paper titled Levees: A Dam by Any Other Name, asked the audience of about 80 consultants, state regulators, and federal agency employees a series of questions about their perceptions of levees. Five years later, in early 2006, ASDSO surveyed state dam safety programs with a related set of questions
The responses given to these surveys, as well as more recent discussions and statements by dam safety professionals, offer an interesting view of levees as an engineering and regulatory "gray area." Below is a discussion of the responses to the 2001 questions, then and now.

Question 1: Are levees and floodwalls really dams by another name?—At the 2001 ASDSO annual conference, approximately 60 percent of the levees session audience agreed that levees and floodwalls are, in fact, equivalent to flood control dams, or "dry dams," and should be considered as dams. The presenters stated, "Based on this non-scientific poll, it appears that levees and floodwalls should be a topic of discussion in the dam safety community."

Their pre-Katrina conclusion was prescient; five years later, almost 100 percent of conference attendees informally polled said levees and floodwalls were essentially flood control dams and carried with them the same engineering issues. In addition, Congress is now considering levee legislation that closely mirrors the National Dam Safety Program Act (see "A levee or a dam?" below).

During the American Society of Civil Engineers (ASCE) 2006 Policy Week, an annual event held in March in Washington, D.C., a group of transportation and dam safety engineers pondered a similar question: "What is the difference between a levee and a dam?" Various explanations were offered, including the following simplified definitions:

  • a dam usually holds water, a levee usually doesn’t; 
  • dams are at lakes, levees are at rivers; 
  • dams are barriers, and levees are guard rails; and 
  • a levee deals with time, a dam, with space.

As for state levee management policy, the 2006 ASDSO survey of state dam safety programs revealed a fairly even split. Within 23 states, regulatory authority or responsibility over levees rests within the same agency as the dam safety program. Yet, many of these states revealed that very little is being done—possibly because of budget restraints—to regulate levees at the state level. Twenty-four states indicated that their states had little or no regulatory authority over levees. (Three states did not respond.)

As 2006 progressed, ASDSO leadership, finding no strategic goal within ASDSO’s policies to address levee safety and realizing that the levee safety issue should be an important association matter, passed a resolution stating, in part, that "… levees and dams share many aspects of design, construction, inspection, maintenance, hazard potential, emergency action planning, and security, and … both levee safety and dam safety programs are critical to public safety and protection and the environment." Through this resolution, ASDSO pronounced its collective support for a national levee safety program.

Question 2: Should levees have hazard-potential classifications similar to dams?—Dams are classified by hazard potential; that is, anticipated losses—human and economic—expected to occur in the event of a dam failure. Each state has its own hazard-potential classification scheme, generally based on guidelines of the Interagency Committee on Dam Safety.

In 2001, about 80 percent of the levees session audience agreed that levees should have hazard-potential classifications similar to dams. One specific comment was that if levees could be so classified, it might be possible for state regulators to obtain the staff and funding necessary to inspect and regulate these structures.

Currently, a handful of states classify levees according to hazard potential, which affects minimum design criteria and inspection schedules.

Now, ASDSO is contributing to a national interagency task force that is working to set national policy on a future levee safety program. The task force includes the Association of State Floodplain Managers, Federal Emergency Management Agency (FEMA), U.S. Army Corps of Engineers (USACE), and the National Association of Flood and Stormwater Management Agencies. To date, these experts agree that part of this effort should include levee hazard potential classification criteria similar to the aforementioned dam hazard potential classification system.

Question 3: Do these critical infrastructure elements (levees) get adequate attention?—Perhaps because it followed the presentation of slides showing poorly maintained levee systems, this question elicited an emphatic "No!" at the 2001 ASDSO conference. Attendees agreed that, had levees been included in the 2001 ASCE Report Card for America’s Infrastructure, the grade would be between a D and an F.

Currently, there is no category for levees in the national ASCE Report Card, but the California version includes a category for "Levees/Flood Control," which earned the lone "F" among nine types of infrastructure. In explanation for the dismal grade, California’s Infrastructure Report Card Committee said, "There is real potential for catastrophic disaster to life and property in California. This is due to the fragile condition of our Levee system. These fragile levee systems protect thousands of homes and billions of dollars in critical infrastructure. Annual investment of $4.2 billion is necessary to reduce the impacts of potential catastrophic failure."

Californians have seen firsthand the destruction that can result from failed levees. In June 2004, the Jones Tract breach near Stockton resulted in damages exceeding $90 million. A present concern is the Sacramento—San Joaquin Delta, which contains 1,345 miles of levees that protect 750,000 acres of land. These levees are similar to those at Lake Ponchartrain, continuously holding back water and protecting land that is mostly below sea level.

As Marty McCann, head of the National Performance of Dams Program at Stanford University and a member of a team undertaking a joint state/USACE Delta Risk Management Strategy Project, explained, "A delta levee incident can have severe consequences, not only in the delta, but nationwide. The consequences of a large multi-breach event could cause billions of dollars worth of damages within the delta alone, and the salinity that would be drawn in from the bay would shut down water export by state and federal water projects and would likely have devastating agricultural and environmental consequences as well."

In its 2006 survey of state dam safety programs, ASDSO did not pose this question, but state responses to another item indicate support for greater attention to levees: "From your general knowledge, are there levees in your state that cause concern from a safety standpoint?" Twelve states expressed no concern, 10 were unsure, and 25 responded affirmatively. Needless to say, California’s response termed levees "a major concern."

Question 4: Should levees be included in the National Inventory of Dams (NID)?—There is a clear need for an inventory of levees. We cannot expect adequate oversight of structures if we don’t know the extent of the problem nationally.

At Dam Safety 2001, this question ignited a discussion on how levees should be catalogued. About 1/4 of the audience said that levees should be included in the NID. Based on the ensuing discussion, the presenters concluded that the audience was concerned that specific NID fields would not apply to levees and that fields required for levees would not apply to dams.

The proposed National Levee Safety Program addresses this issue by separating the inventories but leaving a single branch of the USACE in charge of both. The drafted legislation is part of the Water Resources Development Act, which has already passed the Senate. The Senate legislation provides $542 million over five years for a national levee safety program. Of that, $50 million is set aside for a national levee inventory, $35 million to fund a levee safety program, and $454 million to conduct safety assessments of federal levees. The House Transportation and Infrastructure Committee passed the House version, H.R. 4650, which the full House is expected to pass by the end of the year. According to Brian Pallasch, ASCE director of government relations, funding that would be provided through the House legislation—$75 million over 6 years for risk assessment, cataloging, and a state assistance program—is insufficient.

Eric Halpin, special assistant for dam safety and chief, Engineering Technical Services Branch for the USACE, noted that recent advances in technology complicate this issue somewhat. "The levee inventory will be GIS-based," he said. "This is a quantum leap, and it will become the model for the NID." Congress has authorized increased funding levels for the NID to address this issue, and to add fields for results of inspections and assessments.

Even though this legislation is currently in limbo, Congress has appropriated approximately $30 million for the USACE to proceed with an inventory and assessment of levees under its purview. These include projects designed, constructed, and owned by the USACE; projects designed and constructed by the USACE, but owned and operated by others; and projects the USACE did not design or construct, but now own and operate. The USACE expects to send a report on these initial investigations to Congress in late 2006.

Question 5: Should levees come under state dam safety regulations?—The audience was split about 50-50 on this question in 2001, and, as previously noted, it appears that the ratio applies in 2006. As most state dam safety programs are already understaffed and inadequately funded, many are reluctant to assume additional responsibility. Comments in response to ASDSO’s 2006 levee survey reveal some states’ positions on this question:

  • "The department has authority for periodic inspection of levees, but we have not had the resources to do that. In the last few years, we have taken steps to inventory high hazard levees with an eye toward inspection and more active safety regulation." 
  • "The current dam safety program does not have a list of all the levees nor the resources to add them to the inspection responsibilities." 
  • "[Our state] is in the very early stages of its dam safety program. The inclusion of issues relative to levee regulation at this time will not be possible." 
  • "To design, construct, and maintain levees to the same standards as dams will require funding and effort well beyond that which has been allocated for this in the past. Levees may be a good case for risk assessment. Certainly, levees in New Orleans deserve more attention than a levee protecting uninhabited farmland."

Sponsors of the draft National Levee Safety Act think that states should be regulating levees in much the same way they regulate dams. Provisions in the bill currently provide assistance funds to states to help them set up and administer levee safety programs.

Changes for ASDSO

The issues surrounding levee safety not only intersect dam safety engineering and regulation but affect policies and programs operated by floodplain and stormwater managers and FEMA’s National Flood Insurance Program. Representatives of these programs are collaborating on efforts to shape real change in the way we perceive levees, their safety, and their impacts on the communities they were built to protect.

The newly formed Interagency Levee Policy Committee is focusing on how to merge new understandings of what levees mean to a community, relative to the ability of levees to increase flood risk reduction. It will consider existing paradigms surrounding flood insurance programs and how levees fit into the procedures for setting premiums. Within this structure, ASDSO will be coming to the table as a state regulatory and engineering expert and advocating for additional state and federal resources, if regulatory authority for non-federal levees is added to state jurisdictions.

ASDSO, supported by its recently passed resolution, will continue to advocate for the National Levee Safety Program. This initiative and funding could provide the much needed impetus for establishing state levee safety programs.

Final thoughts

Regardless of the definitions, similarities, and distinctions, most people well-versed in water retention structures probably agree with a statement made by Eric Halpin with the USACE at Dam Safety 2006: "Lessons on levees apply to dams …without exception."

This was not an unfamiliar concept to ASDSO members, who have long lamented that it takes a catastrophe to raise awareness of the importance of dam safety.

Although levee systems tend to be more complex than dams—because of their geospatial, political, social, legal, and ownership complexities—the risks posed to urban areas protected by levees are comparable to the highest-risk dams. The tragedy of New Orleans has proved that, as with dams, the cost of effective regulation and management of levee systems is small compared with the cost of failures.

Sarah Mayfield is information specialist for ASDSO, located in Lexington, Ky. She can be reached at smayfield@damsafety.org. Lori Spragens, ASDSO executive director, can be contacted at lspragens@damsafety.org. For more information about ASDSO, visit www.damsafety.org.

A levee or a dam?
The National Levee Safety bill (H.R. 4650) defines a levee as "… an embankment (including floodwalls)—(i) the primary purpose of which is to provide hurricane and flood protection relating to seasonal high water and storm surges; and (ii) that normally is subject to water loading for only a few days or weeks during a year. The term levee includes structures along drainage canals that are subject to more frequent water loadings but that do not constitute a barrier across a water course."

According to the National Dam Safety Act, "The term dam
(A) means any artificial barrier that has the ability to impound water, wastewater, or any liquid-borne material, for the purpose of storage or control of water, that

(i) is 25 feet or more in height from (I) the natural bed of the stream channel or watercourse measured at the downstream toe of the barrier; or (II) if the barrier is not across a stream channel or watercourse, from the lowest elevation of the outside limit of the barrier; to the maximum water storage elevation; or

(ii) has an impounding capacity for maximum storage elevation of 50 acre-feet or more; but

(B) does not include

(i) a levee; or

(ii) a barrier described in subparagraph (A) that (I) is 6 feet or less in height regardless of storage capacity; or (II) has a storage capacity at the maximum water storage elevation that is 15 acre-feet or less regardless of height; unless the barrier, because of the location of the barrier or another physical characteristic of the barrier, is likely to pose a significant threat to human life or property if the barrier fails (as determined by the Secretary). 

The National Levee Safety bill (H.R. 4650) defines a levee as "… an embankment (including floodwalls)—(i) the primary purpose of which is to provide hurricane and flood protection relating to seasonal high water and storm surges; and (ii) that normally is subject to water loading for only a few days or weeks during a year. The term levee includes structures along drainage canals that are subject to more frequent water loadings but that do not constitute a barrier across a water course."
According to the National Dam Safety Act, "The term dam
(A) means any artificial barrier that has the ability to impound water, wastewater, or any liquid-borne material, for the purpose of storage or control of water, that
(i) is 25 feet or more in height from (I) the natural bed of the stream channel or watercourse measured at the downstream toe of the barrier; or (II) if the barrier is not across a stream channel or watercourse, from the lowest elevation of the outside limit of the barrier; to the maximum water storage elevation; or
(ii) has an impounding capacity for maximum storage elevation of 50 acre-feet or more; but

(B) does not include

(i) a levee; or

(ii) a barrier described in subparagraph (A) that (I) is 6 feet or less in height regardless of storage capacity; or (II) has a storage capacity at the maximum water storage elevation that is 15 acre-feet or less regardless of height; unless the barrier, because of the location of the barrier or another physical characteristic of the barrier, is likely to pose a significant threat to human life or property if the barrier fails (as determined by the Secretary).


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