Environmental Windows

Posted on

The Sudbury Group (New England Regional Dredging Team) is exploring how Environmental Windows (EWs, also known as Time of Year restrictions; TOY) are used in New England to manage impacts of dredging activities on coastal resources (fish, shellfish). This is a topic of concern to many members of the team. The National Dredging Team has also identified this topic as a priority and has asked regional teams to provide feedback to the national level.

Recent Developments

Engineering Research and Development Center Range Finding Study

The Engineering Research and Development Center (ERDC) has begun a ‘range-finding’ study to determine effects of sedimentation of clean sediment on winter flounder eggs and early life stages.  A major concern cited is the generation of suspended sediments near dredging operations to which a wide range of adverse effects,  including fish migration spawning, oyster and clam survival and reproduction and aquatic plant survival, have been attributed.

Winter flounder will be used to show how specific suspended sediment data can be used to more plausibly set EWs for specific areas where dredging operations routinely occur. These experiments will be conducted in the Fish Larvae and Egg Exposure System (FLEES), a dedicated modular and flexible flow-through exposure facility that delivers consistent suspended sediment concentrations in multiple experimental aquaria. The study endpoints can be varied to meet study objectives (e.g., survival, hatching success, growth, etc.) and to specifically address species and life stages used to set EWs.

As part of this study ERDC staff administered an online survey to collect information from stakeholders (resource managers and project managers) in the New England Region about appropriate range finding approaches to use in the study.  The results of this survey were presented at two webinars on December 5 and 11, 2015.  At the NERDT April 2015 meeting, ERDC staff provided an update to the range-finding experiment.

During discussions of the context of effects studies, the participants referenced several key studies conducted recently.  These include a study of winter flounder eggs and larvae by Walter Berry and URI scientist and two studies conducted in New York Harbor by Dara Wilber and colleagues [Wilbur et al. juv, and eggs].

Massachusetts Division of Marine Fisheries Final Report

Marine Fisheries Time of Year Restrictions (TOYs) for Coastal Alteration Projects

Appendix B from Final Toy Report

This final report defines the Massachusetts Division of Marine Fisheries’ recommendations for seasonal or time of year restrictions (TOYs) on in-water construction work. The TOY date ranges were established to protect times during which there is a higher risk of known or anticipated significant lethal, sub-lethal, or behavioral impacts to marine fisheries resources. Using the best available life history information on marine fisheries resources in Massachusetts, this report provides a clear record of how the TOYs are determined.

Massachusetts Division of Marine Fisheries provides recommendations for dredging on Cape Cod. Following up on their work describing the time of year restrictions for marine species in Massachusetts, the DMF Fisheries Habitat Program recently finalized recommendations to minimize hydraulic dredging impacts on marine fisheries resources for Cape Cod and the Islands.

Cape Cod and Islands Resource Recommendations for Municipal Dredging (MA DMF Link)

Cape Cod Dredging Recommendations 3-28-12

Appendix A, town waterbody feature maps

Appendix B, dredge locations and marine resources

NDT Meeting

We would encourage participants in the NDT/RDT meeting to take this survey and ask members of your RDT to take the survey as well. It would be particularly helpful to get both windows setters (State and Federal resource agencies) as well as window observers (Corps and Project Sponsors) to take the survey.

Take the survey

At the end of the survey you will be brought back to this page and can view the results of the survey thus far.

Results of the Survey

We used this survey to stimulate discussion at the NERDT meeting on 2/26/09. The results of the NERDT survey were presented in four separate files:

Powerpoint of the overall results grouped by strength of agreement
Environmental Windows Survey Text

Results of the questions grouped by topic in bar charts
Survey Summary Charts

Results of selected questions analyzed by the role of the respondent in Environmental Windows
Survey Summary Cross Tab Knowledge Charts

Results of the question: What are two things that you would want to change about Environmental Windows
Two Things to Change

The full results of the survey can be accessed here.
Survey Summary On Environmental Windows

As a result of the discussion of the survey results actions have been identified and will be forwarded to State Dredging Teams.

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 during these periods. Environmental windows, therefore, are used as a management tool for reducing the potentially harmful impacts of dredging activities on aquatic resources. The first environmental windows were established more than 30 years ago and, according to the U.S. Army Corps of Engineers (USACE), are applied today to more than 80 percent of all federal dredging projects. In 2001, the National Research Council’s Transportation Research Board conducted a workshop to explore the decision-making process used to establish environmental windows, as well as the consistency of the windows-setting process.

NAS Report on Process for Setting Environmental Windows

Boston Harbor Plume Monitoring

At the NERDT’s October 21, 2008 meeting, Tay Evans, Mike Johnson, and Ed O’Donnell gave presentations with case studies of environmental windows issues in New England and the team initiated a discussion that will be continued at future meetings.