Wetlands Compensation: Techniques for Restoring Lost Functions and Values
- Date: March, 1997 contact: 207-287-3901
While state and federal laws clearly establish that avoiding loss of or damage to wetlands is the prime objective, the laws recognize that there will be occasions when other, more pressing needs will dictate that wetland loss or damage is unavoidable. The two most common concerns are when activities associated with such needs: 1) damage wetlands or impede their functions; or 2) destroy a wetland by filling or dewatering it. In such instances, the law requires that the party causing the loss or damage must act to mitigate these effects, that is compensate for them. This mitigation can take one of four forms, in order of preference:
1) restoration, returning a damaged wetland as close as possible to its original condition prior to the damage;
2) enhancement, making changes or improvements to wetlands to replace the functions or values performed by the wetlands lost or damaged;
3) preservation, protecting wetlands in an adjacent area that are equivalent to the area damaged and that might otherwise be subject to an unregulated activity;
4) creation, converting a non-wetland area into a wetland with all of the physical and biological characteristics to replace the area lost or damaged.
This DEP Issue Profile answers questions commonly asked regarding these wetland compensation techniques.
What are the legal prerequisites governing wetlands compensation?
The wetland protection rules under Maine's Natural Resources Protection Act (NRPA) establish four specific criteria an applicant must meet regarding a proposed wetland compensation project (aside from preservation). These are:
1) expertise - applicants must demonstrate sufficient scientific expertise to carry out the compensation work proposed;
2) financial resources - applicants must demonstrate sufficient financial resources to complete the proposed compensation work, including subsequent monitoring and corrective actions;
3) persistence - applicants must present evidence that, based upon a functional assessment of a proposed restoration, enhancement or creation project, a minimum of 85 percent of the compensation wetland area must successfully replace the altered wetland's functions and values after a period of three years; and
4) monitoring - applicants must establish a plan for monitoring a restored or created wetland over a minimum of three years, including contingency plans for replanting, contouring or other corrections if the project fails to meet its goals during that time.
How are wetlands restored?
In the restoration approach to mitigation, the applicant returns a damaged wetland as closely as possible to its original condition. It is impossible to "totally duplicate" a naturally-occurring wetland; however, individual functions and systems may be approximated and restored. Restoration means that the wetland will perform the same physical functions and possess the same biological conditions as existed prior to damage. Perhaps the greatest concern in restoration is long-term success, for while it may be possible to recreate circumstances for a brief period, nature must ultimately take over and continue these functions over time.
Other factors to consider in evaluating the potential for restoration include:
flood storage and conveyance. Site topography is the critical factor governing a wetland's flood storage and conveyance functions. It is also the most readily restored.
pollution control. Some functions such as sediment trapping may be easily assessed and restored; however, other functions (e.g., immobilization of toxic metals) may be difficult to duplicate, especially for the long range future of the site.
groundwater recharge and discharge. These functions are more difficult to identify, and thus duplicate. Furthermore, soil permeability may change during the restoration process (e.g., a sandy substrate may rapidly become impermeable due to the deposition of organics, not unlike the way a kitchen drain clogs with the residue rinsed from the dinner dishes).
food chain functions. While some may be readily identified and restored (e.g., foliage on which deer feed), others may be more subtle (e.g., micro-organisms on which other species feed).
fish and wildlife habitat. Some functions are readily duplicated (e.g., marsh conditions to benefit waterfowl). Others are more difficult (e.g., fisheries depend upon a delicate balance of species and habitat).
aesthetics. Visual characteristics are, in general, much easier to restore than complex ecological functions.
heritage or archaeological features. Since these have value because of their long term, undisturbed presence, they are impossible to replace or restore.
How does wetland enhancement work?
In a wetland enhancement strategy a developer proposes to make alterations and improvements in the area that result in an increase in the net value of the wetland. For example, if the wetland area contained an overall capacity for water storage, the enhancements would result in expanded water storage capacity by increasing the capacity of some areas to compensate for other areas that are lost. Similarly, if the area provided an overall acreage of a specific type of wildlife habitat, the enhancements would assure that there is an increase of wildlife habitat acreage. Or, other functions or values which are not provided by the wetland can be designed to increase the net value of the wetland. The factors associated with restoration noted above also are considerations in any wetlands enhancement strategy to assure that the enhancement program is successful and that these measures will work over the long term.
How does wetland preservation compensate for lost wetlands?
Since wetlands may be lost to development in other areas, taking steps to preserve such wetlands protects them from loss to other developers. If a developer has several similar parcels of land with similar wetland values upon which development would be allowed without permitting, preserving some areas can be compensation for losses in other areas.
How does a developer preserve a wetland?
There are many preservation methods available to developers. In the example cited above, the landowner may hold title to the area preserved with deed restrictions on the title to prevent development in perpetuity. The developer might also donate the area to be protected to a local land trust or to a conservation organization to protect it in perpetuity. Organizations like the Nature Conservancy and Maine Coast Heritage Trust can help developers to choose the option best-suited to their circumstances.
How does wetland creation compensate for lost wetland?
Section 404 of the Clean Water Act provides for the creation of wetlands as compensation for unavoidable wetlands loss. In creating new wetland,a developer must consider the same factors outlined for wetland restoration, above, to assure that the new wetland replace the functions of the wetland lost.
What is the technical procedure for wetland restoration or creation?
Wetland creation or restoration projects have been undertaken across the nation, including numerous examples in Maine and New England. There is enough experience now to outline a model wetland creation process. While the actual process will be painstaking in detail, it will generally include the following six steps:
Six Steps to a Potential Model Compensation Project
1) Develop project goals and objectives. Using resource inventories and analyses, identify what specific functions the wetlands to be lost performs. Determine how best to design the replacement or restoration project to assure that the lost functions are to be replaced or enhanced by the project.
2) Project Design. This step generally focuses on how to create on the restoration/ replacement site the proper hydrologic regime, that is the mix of soils, terrain, saturation level, topography, etc. that will make the area perform the same functions as well or better than the wetlands it replaces.
3) Site preparation. Once design is complete, the process proceeds with actual physical alteration of the site through excavation and/or water level control. The most critical consideration at this stage is achieving the site hydrology objectives of the project design. If the area is either too wet or too dry it may not support the number and types of plant species that can occur naturally on the site.
4) Soils. After preliminary excavation is completed and desired water levels are established, the next critical step is achieving the delicate balance of soil types on the site that will ultimately determine whether or not the site will function over the long haul as the design intends. Qualified wetland scientists must carefully supervise and monitor the project during this stage.
5) Vegetation. Once the site performs the desired hydrologic functions, the next critical step is establishing the proper types of plant life on the site in the proper numbers and proportion. Since the site duplicates naturally occurring conditions on the site, plants from surrounding wetland areas can usually be counted on to colonize the site. However, in most instances, seeding and/or transplanting appropriate vegetation is required to speed up this process. As the site takes on all of the characteristics desired, wildlife will also begin to appear in desired species and quantities.
6) Monitoring. Despite all of the careful planning, precise construction and other steps in the process, the site may not perform exactly as intended, or it may be initially successful but fail later. The true test of the project's success is how it functions over time. This demands that the site's hydrology, vegetation and wildlife be carefully monitored to document whether or not it is functioning properly and continues to do so.
Can developers take steps to prepare for the possible future loss of wetlands?
Yes. Specifically, the rules under the NRPA allow for "mitigation banking." This allows an applicant to create, restore, enhance or preserve wetlands as "credit" to offset future project impacts. Applicants must meet all of the standards set forth above. In addition, the compensation work must take place in the same watershed, or in the project vicinity of any future alteration work planned and as close as possible to the proposed wetland alteration site(s). In any event, no applicant may propose to use mitigation banking to compensate for more than 25 acres of wetlands alteration in any one year period.
For more information about wetlands compensation, contact DEP staff at one of the following locations:
17 State House Station
Ray Building, AMHI Complex
Augusta, ME 04333
Eastern Maine Regional Office
106 Hogan Road
Bangor, ME 04401
Northern Maine Regional Office
528 Central Drive
Presque Isle, ME 04769
Southern Maine Regional Office
312 Canco Road
Portland, ME 04103