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Introduction
Environmental windows are those periods of the year when dredging and disposal activities may be carried out because regulators have determined that the adverse impacts associated with dredging and disposal can be reduced below critical thresholds at these times. Conversely, seasonal restrictions are applied during periods of the year when dredging and disposal activities are prohibited because of the increased potential for harm to aquatic resources. Environmental windows are one of a number of management and technological tools that can be used individually or in combination to reduce the environmental impacts of dredging and disposal operations on living resources, aesthetics, and recreation and tourism. This report presents the findings and recommendations of a committee of experts formed to examine the decision-making process for establishing environmental windows and provide recommendations for improving the process. These recommendations are based largely on the results of a workshop held to (a) explore the decision-making process for establishing environmental windows and (b) examine options for introducing greater consistency, reliability, and predictability into the process.
Background
Environmental windows are most frequently designed to provide an opportunity for dredging while protecting against the following primary stressors generated during dredging and disposal operations:
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Entrainment of fish eggs and larvae, juvenile fishes, sea turtles, and other threatened or endangered species;
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Suspended sediments and turbidity, which may affect fish and shellfish spawning, disrupt anadromous fish migrations, reduce water quality, and cause aesthetic degradation;
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Resuspension of buried contaminated sediments, which may release toxins and nutrients that can have acute and chronic effects on living resources;
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Sedimentation (burial of plants and animals and economic resources);
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Habitat loss by burial, removal, or degradation; and
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Collisions with marine mammals (e.g., whales).
For each dredging project, the goal of resource agencies and the U.S. Army Corps of Engineers (USACE) is to achieve cost-effective dredging and disposal while maintaining and protecting aquatic resources—living resources, aesthetic resources, and recreational and tourism activities. Accomplishing this goal is frequently a challenging balancing act. In conducting dredging projects, USACE must be cognizant not only of the need to protect natural resources but also of project timelines, the availability of equipment, and the safety risks posed to dredging personnel by operating in potentially inclement weather and sea states. Ports must also weigh the risks to ships and their crews and the economic losses associated with project delays. Resource managers, on the other hand, must consider potential damage to the life histories of multiple species (particularly those that are threatened or endangered) that reside in or migrate through dredging and disposal areas, along with critical habitat concerns, when making recommendations for restricted periods and environmental windows. Yet biologists and regulatory agencies are frequently hampered in their mission to protect critical resources by a lack of definitive scientific information on either the susceptibility of the resources to dredging stressors or the actual biological impacts. In these cases, the agencies that are charged with protecting public resources have historically adopted a conservative or risk-averse approach, resulting in recommendations for narrow dredging windows. The establishment of environmental windows also frequently involves multiple state and federal agencies that may follow different procedures in recommending windows.1
Since the passage of the National Environmental Policy Act in 1969, resource agencies have requested environmental restrictions with increasing frequency.
According to USACE, environmental windows today are applied to more than 80 percent of all federal dredging projects. Because of the frequency of recommendations to impose environmental windows and the cumulative economic impact of their application for more than 30 years,2 USACE recently challenged the efficacy of the windows-setting process. Moreover, USACE questioned the scientific validity of establishing windows in the absence of definitive scientific information, and called for greater consistency, predictability, and reliability in the process.
Purpose
Given the above concerns, USACE asked the National Research Council’s Transportation Research Board—Marine Board to undertake an examination of the application of environmental dredging windows in federal navigation projects; this effort was conducted in collaboration with the Ocean Studies Board. USACE requested a workshop to explore the decision-making process for establishing environmental windows and to solicit suggestions for improving the process. The statement of task for the project is shown in Box 1-1.
To carry out this charge, a committee was appointed with expertise in port operations, dredging, benthic and wetland ecology, commercial fishing, sedimentology, ichthyology, environmental protection, and federal and state regulation. The committee chose to place particular emphasis on the last portion of its statement of task—the development of a pilot process for setting, managing, and monitoring environmental windows. The workshop was designed to solicit the views of a wide range of experts and interested parties involved in and affected by the establishment of environmental windows. The workshop discussions on the regulatory, scientific, and economic issues associated with windows and participants’ reactions to a proposed pilot process presented at the workshop assisted the committee in developing a pilot process that could be used to improve the technical and scientific bases used for establishing windows.
Organization of This Report
Chapter 2 details the research and outreach efforts conducted in preparation for the workshop, the workshop structure and rationale, and the major points made during the proceedings. Chapter 3 presents a template for a proposed
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BOX 1-1 Statement of Task This workshop will be used to identify issues and discuss options that could lead to greater consistency in the procedures used by the U.S. Army Corps of Engineers in setting environmental windows. It is anticipated that the workshop will have several panels covering topics such as: the wide range of laws and regulations establishing bases for various protection measures; knowns and unknowns about the biological consequences of alternate dredging methodologies; new developments in dredging techniques; better (and worse) examples of decision making for windows in different regions; models of collaborative decision making in other environmental and transportation areas; and tools (processes, analytical models, etc.) for improving decision making. Workshop participants will be invited to represent a cross-section of groups involved in setting windows, including federal and state resource agency staff, experts in dredging, port officials, environmental groups, and academic experts from the variety of relevant fields. The workshop will be designed to ensure opportunities for dialogue and information exchange. The summary will provide an identification of the issues raised and the opinions expressed both pro and con on these issues. The project committee will also provide ideas and suggestions for appropriate follow-up activities, such as additional research, workshops, or a pilot process for setting, managing, and monitoring environmental windows. |
process for setting, managing, and monitoring environmental windows, developed in draft form by the committee prior to the workshop and refined in accordance with the workshop discussions. Chapter 4 provides recommendations formulated by the committee, largely on the basis of information that emerged from the workshop. Appendix A contains summaries of the workshop sessions, Appendix B is a glossary of terms relevant to this report, Appendix C provides the workshop agenda and a listing of the participants, and Appendixes D and E contain copies of the forms used to solicit information and feedback from various stakeholders. A final section presents biographical information on the committee members.
