Gulf of Maine: Council on the Marine Environment

Gulf of Maine Projects

1996 Coastal Habitat Restoration Report

Tidal Marshes

Restoration of tidal marshes may be conducted either to mitigate for permitted impacts or to compensate and offset cumulative or historical impacts through proactive efforts. For the 111 tidal marsh restoration projects listed in Table 1, including both mitigation and proactive projects, 45 involved tidal restrictions, 42 involved the removal of fill, 19 involved the creation of tidal marsh habitat, and 35 involved Open Marsh Water Management. Some projects may have involved more than one type of restoration work. Compensatory mitigation and proactive projects are very different in terms of project objectives, and, quite often, in the type of work conducted.

Mitigation

Compensatory mitigation projects aim to compensate for unavoidable adverse impacts through the restoration, creation, or enhancement of natural resources. The primary goal of these projects is to replace habitat functions and values lost during a permitted activity. These projects are often the least cost effective, especially those that involve habitat creation such as the conversion of an upland habitat to a tidal wetland. For example, it cost Logan Airport in Boston over $700,000 to construct a 1.3 acre salt marsh (Louis Berger & Assoc., 1997). This high cost reflects the high expense of permitting, planning, and construction often involved with compensatory mitigation projects.

As Table 2 shows, many opportunities for restoration have been identified. If restoration opportunities do not exist on-site for effective compensatory mitigation, resources should be allocated to support projects offsite. Mitigation banks are designed to pool money from mitigation and implement larger and more effective restoration projects. Restoration sites selected for mitigation banks may be located outside of the town where impacts occurred. This makes it difficult to convince local municipalities of the long-term ecological benefits. Information collected indicates that few mitigation projects are tracked and evaluated on a long-term basis and reveals the need for more rigorous tracking programs to enforce permit compliance and to document ecological changes. Existing permit tracking databases could be modified to include information on acres impacted versus acres restored and a brief description of the type and location of compensatory work. In addition, monitoring and assessment reports need to be written in a consistent manner and their submittal to regulatory agencies enforced.

Proactive

Proactive projects aim to restore degraded habitats to offset historical and cumulative impacts rather than compensate for permitted activities. These projects are becoming numerous and are often the most cost effective (other than conservation of existing habitats) due to the types of work involved and in-kind contributions of resources. By replacing a culvert or installing a self-regulating tide gate, tidal marshes can be restored at minimal cost. For example, restoring tidal flow to a 50 acre salt marsh in Rye, New Hampshire, was completed at a cost of $40,000 (Louis Berger & Assoc.,1997). Other projects may involve the excavation of fill material and planting of vegetation or Open Marsh Water Management (OMWM). OMWM aims to restore ditched and drained wetlands and control mosquito populations. Resources need to be allocated toward initiatives that identify and evaluate restoration opportunities, and more importantly, toward those projects that have already been identified as having strong restoration potential. (See Table2.)