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
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
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.
- 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.
- 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)
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