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Project Summary

Acadia National Park in Maine is working to rehabilitate historic road systems and culverts that have been damaged by increasingly frequent flooding and erosion events that were causing maintenance and visitor use closures.

Project Background

Acadia National Park contains three historic circulation systems listed in the National Register of Historic Places (200 km/120 mi of hiking trails, 90 km/56 mi of carriage roads, and 50 km/33 mi of paved motor roads, with associated bridges and drainage structures). The drainage features are undersized for current conditions, as average annual precipitation has increased by 11.9 cm (4.7 in) in the past 100 years.

Over the past 10 years, the park has experienced flooding and erosion events that appear to relate to storm events that are increasing in both number and severity. Erosion has damaged roads and trails and caused redeposition of gravel into adjacent wetlands, requiring increasingly frequent maintenance cycles and closure of popular visitor sites. Resource management staff also documented sedimentation into wetlands and impaired natural processes in stream systems restricting access for migratory fish and amphibians. Coastal storm surges have flooded and damaged historic sites and roads. With climate model scenarios generally anticipating increased frequency of intense rainfall events, we anticipate that these problems will worsen and substantially affect visitor access and use of the park. Information regarding probable future flood streamflows is needed to help the National Park Service (NPS) properly size new hydraulic structures to accommodate the expected increased flows under the projected range of climatic conditions. 

Project Implementation

The park began a multi-pronged effort of inventory, monitoring, mitigation, and rehabilitation along the historic road systems. Consulting engineers and hydrologists inventoried all culverts, headwalls, and bridges. Using hydro-geomorphic data, they re-engineered the structures to be suitable for projected stream hydrology changes while maintaining the character-defining features of the historic structures. Information used in planning includes climate change scenarios (US Geological Survey [USGS] climate data models for the northeast) and hydrologic modeling data (USGS). The rehabilitated crossings have the added benefit of restoring aquatic animal passages (primarily migratory fishes and amphibians), and restoring natural hydrological processes for impaired stream systems. Rehabilitated crossings are monitored for streamflow dynamics and erosion. Watersheds renovated for fish passage are monitored and inventoried by fisheries biologists. 

Project Outcomes and Conclusions

To develop a better understanding of how climate change will impact future stream flood flows, the park has requested technical assistance for hydrological analyses. In order to address other anticipated climate impacts, the park has also submitted a number of NPS funding proposals that would allow the park to conduct climate change scenario planning, manage archeological sites, restore subalpine vegetation on Cadillac Mountain, replace stream culverts, model streamflow hydrology, and restore fish habitat in coastal streams. This project is ongoing.

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This case study is part of the 2015 National Park Service report, Coastal Adaptation Strategies: Case Studies. These case studies initially were developed by park managers as part of a NPS-led coastal adaptation training in May 2012. The case studies follow the format created for EcoAdapt’s Climate Adaptation Knowledge Exchange (CAKE) database, including a list of adaptation strategies. All case studies were updated and modified in September 2013 and March 2015 in response to a growing number of requests from coastal parks and other coastal management agencies looking for examples of climate change adaptation strategies for natural and cultural resources and assets along their ocean, lacustrine, and riverine coasts.

Project Keywords

Recommended Citation

Cole-Will, R. (2015). Rehabilitating Stream Crossings on Historic Roads, Acadia National Park, Maine [Case study on a project of Acadia National Park]. Excerpted from Schupp, C.A., R.L. Beavers, and M.A. Caffrey [eds.]. 2015. Coastal Adaptation Strategies: Case Studies. NPS 999/129700. National Park Service, Fort Collins, Colorado. Retrieved from CAKE: www.cakex.org/case-studies/rehabilitating-stream-crossings-historic-road...(Last updated November 2015)