Recommendations for a National Levee Safety Program ...From the National Committee on Levee Safety

Environmental Protection and Levee Safety Activities

Levees and the Natural Environment

The relationship levees have with natural systems is complex. Without judgment as to the wisdom of levees, the simple truth is that levees are a part of the nation's existing flood risk management system, helping to protect thousands of lives and billions of dollars worth of critical infrastructure. As such, their continued and timely maintenance is imperative. However, in doing so, there can be environmental impacts that cannot be ignored.

While levees and their maintenance can result in negative environmental effects (e.g., cutting off the river from its floodplain, altering the natural hydrology of the area by reducing recharge of aquifers, preventing seasonal overbank flooding that can provide needed nutrients to soils, and enabling increased development that can lead to destruction of ecologically important riparian and coastal ecosystems such as wetlands and marsh), it is often these same levees that protect critical infrastructure such as wastewater treatment plants and drinking water filtration plants, which have been located in floodplains in proximity to surface waters. Levees prevent flood waters from overwhelming such structures, thereby safeguarding potable water supplies and preventing release of sewage and other pollutants into the surrounding fragile ecosystem.

The National Committee on Levee Safety believes that a balance between public safety and environmental stewardship can and must be struck — the two fundamental needs have to be brought into harmony.

Harmonizing Levee Safety Activities with Environmental Protection Requirements and Principles

Some of the questions the Committee believes are essential to consider include:

  • Can operations and maintenance practices necessary to maintaining the levee be improved to mitigate or reduce negative impacts on the natural environment or ecosystem without compromising public safety?
  • Can levees or flood risk mitigation projects, including operations and maintenance activities, be designed or modified to reduce negative environmental impacts — or even to enhance or restore the environment?
  • Can streamlining permitting requirements related to levee operations, maintenance, and emergency repairs, and reducing the time required to obtain those permits, improve both the natural environment and public safety, increasing efficiency without shortcutting either the environment or public safety?

Part of the challenge is due to the age of levees — many of the nation's levees were developed, and the operations and maintenance requirements established, before the passage of current environmental protection laws such as the Clean Water Act and the Endangered Species Act. Further, as engineering and environmental sciences both advance, the interaction between levees and the ecosystem in which they operate is better understood.

For levees to perform adequately and reliably, it is essential to perform maintenance and rehabilitation activities before a project becomes functionally impaired or failures begin. Due to shifting legal and regulatory requirements, some levee operators have experienced difficulties obtaining the necessary permits to perform needed operations and maintenance activities on levees or feel like they cannot address deficiencies in a timely manner.

Vegetation on levees is one well recognized area of contradictory information. Vegetation such as trees and shrubs could, in some cases, compromise the structural integrity of levees by providing pathways for seepage, destabilizing soils, and impeding the ability for levee operators to inspect the levee and conduct needed emergency operations. At the same time, such vegetation can be necessary for the survival of some aquatic and terrestrial species, providing shade that lowers water temperatures or habitat for threatened or endangered species. Waterside vegetation may also be beneficial to the structure itself, in some cases, by providing erosion protection or discouraging burrowing animals.

Recommendations for Harmonizing Environmental Protection and Public Safety

In order to better harmonize these perspectives and ensure that the protection of human life and the environment are not unduly compromised, the Committee recommended that the National Levee Safety Program, once established, should:

  • Direct research and development efforts to evaluate operations and maintenance (O&M) practices for existing projects and to develop cost-effective measures to make O&M practices more compatible with present-day natural resource management principles. Research and development should be led by an interdisciplinary team and include these with public safety and environmental expertise. (Recommendation 12)
  • Establish and consult with a standing Advisory Committee on Environment & Safety. This standing committee would be comprised of members from all levels of government and the private and nonprofit sectors with the responsibility to provide advice on the coordination of environmental and safety concerns related to levee operations and maintenance, removal, rehabilitation, and new levee projects. The Advisory Committee on Environment & Safety will also provide advice regarding efforts for improving collaboration regarding environmental protection and safety in leveed areas. (Recommendation 1)
  • Require states to establish an approach to coordinating environmental protection and public safety among each of the state resource agencies as a prerequisite of having a state levee safety program recognized by the National Levee Safety Program and accessing the proposed National Levee Rehabilitation, Improvement, and Flood Mitigation Fund. (Recommendations 14 and 16)

Looking Ahead

Effective flood risk management involves employment of a plethora of strategies, techniques, and tools. To enable communities to make wise decisions regarding the role of levees in flood risk reduction in the future, it is necessary for us to understand fully the benefits and costs of levees in any given location. In addition to an assessment of safety to humans and the economic benefits and costs, we must understand and be able to articulate the impacts that levees have on floodplain ecosystems. We must also take an accounting of what important pollution-control benefits and natural assets levees currently help to protect. Where levees are part of the suite of activities chosen to reduce flood risk, they must perform reliably.

 

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Updated February 2011