Environmental Review Toolkit
Water, Wetlands, and Wildlife

Connecting Transportation and Habitat in Maine

When the Maine Department of Transportation (MaineDOT) maintenance crews discovered a 2-foot drop at the outlet of a stream culvert in the coastal town of Belfast, they solved the problem by burying several New Jersey barriers downstream. The crew left a gap between each barrier and 10 inches of barrier exposed above the stream surface. The embedded barriers raised the stream elevation, enabling trout, frogs, turtles, ribbon snakes, and other aquatic species to get through the culvert to upstream habitat and to rest in the pools created by the barrier gaps.

To fix a severe dropoff at the outlet of a stream culvert, MaineDOT buried several New Jersey barriers downstream, raising the stream elevation so fish could swim through the culvert to upstream habitat. Photo by MaineDOT.
To fix a severe dropoff at the outlet of a stream culvert, MaineDOT buried several New Jersey barriers downstream, raising the stream elevation so fish could swim through the culvert to upstream habitat. Photo by MaineDOT.

Belfast's ingenious and low-cost strategy is an example of MaineDOT's focus on connecting the habitats of aquatic organisms, amphibians, reptiles, and land-based mammals. As other states, Maine is faced with the decades-long problem of habitat loss and fragmentation as well as animal-vehicle collisions that threaten the safety of both wildlife and the traveling public.

Maine's Fish Passage Policy and Design Guide—a groundbreaking design manual developed in 1999-focuses on stream-corridor passage for fish but not on passage for land-based wildlife. As traffic loads and road density are increasing, Maine's highways inevitably impact wildlife and their habitat by breaking larger habitat units into smaller ones and either contributing to animal-vehicle collisions or discouraging animals from trying to cross busy roads.

Gaps between the New Jersey barrers created resting pools for fish and other aquatic species. Photo by MaineDOT.
Gaps between the New Jersey barrers created resting pools for fish and other aquatic species. Photo by MaineDOT.

Luckily, the MaineDOT staff has specially developed Geographic Information System (GIS) maps that allow them to screen highway projects for potential impact on habitat connectivity. The GIS maps show such details as the location of vernal pools and the habitats of spotted turtles. These maps were created by the state's Department of Inland Fisheries and Wildlife through its "Beginning with Habitat" program (BwH). Although BwH was originally envisioned for local governments, MaineDOT engineers and planners have become one of its dedicated users. MaineDOT and its partners from Inland Fisheries and Wildlife, the Maine Department of Environmental Protection, the Maine Natural Areas Program, the Maine State Planning Office, and the Nature Conservancy created a statewide predictive habitat connectivity model. Together, these partners are mapping key overland connections between large, undeveloped blocks of land and target species' habitats in three pilot areas throughout the state. By depicting these areas in the context of BwH maps, MaineDOT staff will increase their ability to identify habitat connections of concern. From this, MaineDOT will be able to incorporate design measures from the outset, improve the accuracy of cost predictions, and reduce costs associated with the redesign of crossing structures.

MaineDOT and its connectivity modeling partners entered into a parallel research project focused on developing standard protocols for species-specific passage structures. The results will help transportation professionals understand how wildlife—even such rare species as the New England cottontail and Northern black racer—use the landscape and are affected by roads and related development.

Thus far, passage structures for land-based wildlife have been largely limited to new road alignments. New alignment projects offer an opportunity to preserve existing habitat linkages, yet they do not typify the most common transportation projects undertaken by MaineDOT—the smaller, regional projects that maintain or replace existing crossings. These smaller, more financially and logistically constrained projects can incorporate measures that maintain or restore habitat linkages for particular species.

To meet cost-associated and logistical challenges, MaineDOT proposes to use available funds to cost share projects on existing alignments. In this plan, MaineDOT will partner with resource agencies and developers to provide the differential in design and construction costs between standard practices and those aimed at maintaining and restoring habitat connections. Projects have been planned in each of the three pilot areas focusing on, but not limited to, species targeted in the research protocols. Effective designs and construction practices identified through this effort will be highlighted in the updated fish-passage design guide, aptly renamed the MaineDOT Waterway and Wildlife Crossing Policy and Design Guide.

For more information contact: Judy C. Gates, judy.gates@maine.gov

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