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Maine Coastal Program
Home > Coastal Habitat Restoration
Coastal Habitat Restoration
The Maine Stream Connectivity Work Group: Working to reverse the natural, economic, and social costs of impaired aquatic systems
Background on Connectivity
An alewife negotiates the last miles of its migration to spawning grounds in a Merrymeeting Bay tributary.
S. Moore photo
Centuries of land and water resource development in Maine, while supporting historical economic and social goals, have impacted Maine’s estuaries, streams, lakes, and other aquatic systems. A notable source of this impairment is the loss of in-stream, or longitudinal connectivity. Dams and road crossings block access to habitat that is critical to the survival of Atlantic salmon, alewife, native brook trout, freshwater mussels and other organisms requiring unimpeded movements throughout watersheds during some or all of their life cycle. Along with these impacts, impaired connectivity also has considerable economic and social costs, including the loss of income and jobs historically supported by thriving commercial and recreational fisheries. Likewise, the population-suppressing effects of lost connectivity on certain riverine species has led to increasingly restrictive, costly and complex environmental regulatory processes created to protect these imperiled organisms from further harm.
Assessing the Scope of the Challenge
Over a half century of diligent restoration effort by public and private organizations in Maine has led to notable successes in re-establishing connectivity. Maine’s dams – especially those that block or hinder the migration of highly-valued species – have attracted much attention from organizations interested in river restoration. Yet recent research by the U.S. Fish and Wildlife Service and other organizations indicates that the scope of impaired connectivity is far greater and complex than previously thought, which may partially explain why recovery of at-risk species relying on connectivity has been limited. For instance, within the historic range of diadromous fish (species that migrate between the ocean and freshwater environments) in Maine, it is estimated that about 10,000 road crossings over perennial streams represent severe barriers to connectivity. The worst of these barriers block the movement of highly valued stream organisms and the materials they require to survive. Correcting these barriers often entails replacing the existing road crossing (usually a culvert) with one of considerably larger size and expense. The National Oceanic and Atmospheric Administration’s Restoration Center notably provides funding and technical assistance for correcting barriers to connectivity, but the sheer number of these barriers in Maine is currently far greater than the capacity of any one organization to adequately address them.
A Framework for Improving State-wide Connectivity
These culverts block the movements of aquatic organisms and the materials they need to survive. E. Witham photo.
Convened in 2009, the Maine Interagency Stream Connectivity Work Group grapples with the challenge of restoring Maine’s aquatic habitats. The group concluded that progress toward recovery of our aquatic systems will be hindered without a coordinated restoration strategy having complimentary programmatic, regulatory, and funding elements. The full list of Work Group recommendations follows below. Each recommendation is designed to maximize returns on previous and future restoration investments in Maine.
The cost of correcting the highest priority barriers to connectivity is high, and private, municipal, and state capacity to meet this challenge is currently insufficient. For road-stream crossings, increased capacity at all levels will be required over time to implement improved design standards that will reverse compromised environmental conditions and benefit at-risk species. Over the coming decades, a program such as that described in #3 below would require considerable amounts of privately-sourced construction materials and/or services at sites located across the state. Consequently, the sustained economic benefit associated with this work could be noteworthy. Road-stream crossings corrected with support from this supplementary funding mechanism would be designed to accommodate recent increases in peak stream flows, which could facilitate an added benefit of reduced maintenance costs for towns. Finally, re-establishing connectivity throughout the state would support long-standing efforts to protect and improve Maine’s valuable recreational and commercial fishing industries.
Recommendations of the Maine Stream Connectivity Work Group
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