A Process for Setting, Managing, and Monitoring Environmental Windows for Dredging Projects: Special Report 262 (2002)

Environmental windows are periods in which regulators have determined that the adverse impacts associated with dredging and disposal can be reduced below critical thresholds, and dredging is therefore permitted. Conversely, seasonal restrictions are applied—dredging and disposal activities are prohibited—when the perceived increase in potential harm to aquatic resources is above critical thresholds. Since passage of the National Environmental Policy Act in 1969, resource agencies have requested environmental restrictions on dredging and disposal activities with increasing frequency. More than 80 percent of the federal contract dredging program is now subject to some type of restriction.

Windows are an intuitively simple means of reducing risk to biological resources from stressors generated during dredging and disposal activities, including entrainment of fish eggs and larvae, resuspension of buried contaminated sediments, habitat loss, and collisions with marine mammals. The use of windows as a management tool, however, can have significant cost implications for both the U.S. Army Corps of Engineers (USACE) and the local sponsors of dredging projects. For example, windows can prolong completion of dredging projects, delay project deadlines, and increase risk to dredging personnel by shifting dredging to periods of potentially inclement weather and sea states. Because both recommendations to impose environmental windows and the cumulative economic impact of their application are increasing, USACE requested that the National Research Council’s Transportation Research Board—Marine Board form a committee of experts to conduct a workshop to explore the decision-making process

for establishing environmental windows and provide suggestions for improving the process.

A committee with expertise in port operations, dredging, benthic and wetland ecology, commercial fishing, sedimentology, ichthyology, environmental protection, and federal and state environmental regulation was formed to conduct the project. The committee gathered information from other experts, conducted case studies, and planned and carried out the workshop. The workshop was designed to solicit the views of the different parties involved in and affected by the process of setting windows. Participants represented ports, federal and state environmental regulatory agencies, environmental interest groups, dredging operations, and relevant academic fields. Breakout sessions were devoted to such topics as how to evaluate trade-offs between environmental benefits and operational costs, the strengths and weaknesses of current decision-making processes, the scientific and technical justifications used in establishing windows, and dredging technologies designed to minimize environmental impact.

Through examination of case studies and discussions with workshop participants, the committee found that the scientific evidence used in setting windows varies greatly. Some decisions appear to be based on outdated data and information, others on the authority of the resource agency, and only a few on scientific observation. Economic and project considerations appear to have been given minimal consideration in the majority of the cases reviewed. The overall impression that emerged from the case studies examined was a discernible lack of consistency in the current windows-setting process.

Prior to the workshop, the committee developed a draft template for a systematic process for achieving greater consistency, predictability, and reliability in decision making related to setting, managing, and monitoring environmental windows. The draft template was then refined to reflect input obtained during the workshop (see Box ES-1). The template embodies an ongoing process that involves all stakeholders and is based on principles of adaptive management. The adaptive nature of the process should make it possible to achieve the consistency, predictability, and reliability lacking today without sacrificing needed flexibility.

The proposed methodology is not dependent on the conduct of new scientific or technical research in the first instance, and can be incorporated into other, ongoing stakeholder processes. Although it is capable of standing on its own, its implementation would be most useful if the process were piloted in a few districts; the pilot program would include training sessions and workshops

demonstrating how the proposed methodology could be integrated into existing processes.

The key to successful implementation of the proposed process is twofold. First, each stakeholder must commit to the integrity and completion of the process (see Step 1). Without a commitment from each government agency involved (both advisory and decision making) to dedicate the necessary financial and staff resources to the process, the methodology will not succeed and should not be attempted. It should also be noted that this process was designed to be implemented in cases in which dredging projects have been congressionally mandated or approved. The starting point for the process is not whether to dredge but how and when to dredge.

Second, a factor that distinguishes this from other windows-setting processes is the interaction between the Science and Engineering Teams specified in Steps 2 and 3. In many instances, experts in dredging technology are working in a vacuum—attempting to develop technologies for reducing the biological impacts of dredging activities without the benefit of clearly specified goals. Interaction among biologists, environmental scientists, dredging technology experts, and those responsible for safe ship operations is critical to the proposed process. Specifically, the methodology calls for the formation of a Science Team charged with identifying those biological resources most likely to be adversely impacted by dredging activities. In addition, the Science Team is to identify the acceptable levels of impact for those species identified as most vulnerable. On the basis of the information provided by the Science Team, the Engineering Team will recommend strategies (e.g., technology, contracting, operational methods, equipment selection) for meeting the target levels of acceptable stress. Using

the strategy recommended by the engineers, the scientists will reassess potential biological impacts and recommend windows accordingly. The committee is confident that by integrating the knowledge provided by both scientists and engineers, the proposed process will lead to the establishment of windows that are predicated on a higher degree of scientific certainty than is presently the case.

The committee’s key findings and recommendations are presented below.

Dredging and disposal operations are only one of a number of human activities that affect the nation’s waterways. They need to be evaluated not only in the absolute sense so that management strategies for reducing environmental impacts to acceptable levels can be developed but also in the context of other activities that affect the uses and value of water bodies important to society.

Environmental windows are one of a number of management and technological tools that can—when properly selected and applied—not only reduce the environmental impacts of dredging and disposal operations but also increase the efficiency and effectiveness of those operations.

Existing processes for setting, managing, and monitoring environmental windows vary widely from region to region. The variations reflect differences among natural environments and their living resources; sociopolitical contexts; and experience with involving stakeholders in resolving complex, multidimensional

issues. It is only through testing and refinement of the proposed process in a variety of settings that the methodology can be refined, endorsed, and incorporated into existing decision-making processes to provide greater consistency.

A series of technical syntheses encompassing field and laboratory studies of environmental stressors, biological resources, and specific life-history stages affected by dredging and disposal operations needs to be undertaken and regularly updated. These syntheses should focus on integrating and interpreting local and regional data and information and placing them in a larger context. Through this process, gaps in scientific information will become apparent and can serve as the focus of future research. These syntheses should be undertaken as an integral part of the recommended pilot studies.

The current divide between those responsible for engineering dredging projects and those responsible for protecting biological resources needs to be narrowed. Each discipline must become better educated about and sensitive to the pressures faced by the other if management tools that satisfy the needs of both parties are to be developed.

Although the process outlined above for setting, managing, and monitoring environmental windows is intuitively simple, its implementation will be challenging because it calls for a balancing of priorities. The most difficult step is Step 4, the balancing of scientific conclusions against economic and societal considerations. Structured decision-making tools can be helpful in addressing these issues.

If resource agency staff are expected to fulfill their mandates under the law and participate in the windows-setting process in a timely manner, the agencies will need additional funding.

The justification for windows needs to be reviewed periodically. All windows ought to be viewed as subject to change on the basis of new data and information that should be incorporated routinely into the windows-setting process.