For more than 20 years, the Division of Ecological Restoration (DER) has assessed and documented the impacts that road-stream crossings and undersized culverts and bridges have on fish and wildlife and biodiversity conservation. Using this information DER supported the development of ecologically-based design guidance, the Massachusetts Stream Crossing Standards, for freshwater stream crossings. That guidance has since been promulgated into state regulation, and demonstrated the economic and public safety benefits to municipalities through culvert replacement projects meeting these standards. In the coastal zone, tidal restrictions have also been documented, assessed, and designed based on their unique conditions and the desire to address similar ecological and infrastructure considerations. However, the same guidance that may apply to freshwater stream crossings in some cases, has been found to conflict with conditions and subsequent guidance within tidally restrictive settings.
With projected climate change and updated estimates of sea-level rise (SLR) for Massachusetts, it is anticipated that approximately 3,000 culvert and bridge crossings seated at the transition between freshwater and estuarine and tidal transition will be directly impacted by changing conditions. There is a pressing need to identify issues, and further develop guidance within this advancing transition zone, for both ecological benefits (continuity, marsh migration, reducing habitat degradation and loss) and economic benefits (reducing future coastal hazards, flood reduction, coastal erosion, infrastructure failure, etc.). DER is facilitating natural resource and infrastructure planning by developing guidance for these transitional stream crossings within near-coastal environments that will experience the impacts of climate change and SLR over the next 50 to 75 years.
This presentation will highlight DER’s work to develop climate resilience guidance for stream crossings in coastal and near-coastal environments. DER’s work will meet climate change resilience goals by providing restoration practitioners and infrastructure designers with tools that can be used to plan and design structures that have the potential to enhance flood (storm and coastal) resiliency, upstream flood storage capacity, utilize best practices to prepare for and reduce coastal erosion and scour, and mitigate resource impacts where coastal transportation corridors are critical for health and human safety. The effort will improve habitat conditions across freshwater coastal and estuarine watersheds by identifying and advancing case-study crossings, within these transitional zones and by facilitating the planning, design, and implementation of crossing upgrades that considers improvements for aquatic passage and restored ecological processes (sediment transport, tidal flushing, water quality).