Water: Coastal Zone Act Reauthorization Amendments
B. Management Measure for Restoration of Wetland and Riparian Areas
Promote the restoration of the preexisting functions in damaged and destroyed wetlands and riparian systems in areas where the systems will serve a significant NPS pollution abatement function.
This management measure is intended to be applied by States to restore the full range of wetlands and riparian functions in areas where the systems have been degraded and destroyed and where they can serve a significant NPS abatement function. Under the Coastal Zone Act Reauthorization Amendments of 1990, States are subject to a number of requirements as they develop coastal NPS programs in conformity with this management measure and will have flexibility in doing so. The application of management measures by States is described more fully in Coastal Nonpoint Pollution Control Program: Program Development and Approval Guidance, published jointly by the U.S. Environmental Protection Agency (EPA) and the National Oceanic and Atmospheric Administration (NOAA) of the U.S. Department of Commerce.
Restoration of wetlands and riparian areas refers to the recovery of a range of functions that existed previously by reestablishing the hydrology, vegetation, and structure characteristics. A restoration management measure should be used in conjunction with other measures addressing the adjacent land use activities and, in some cases, water activities as well.
The term NPS pollution abatement function refers to the ability of a wetland or riparian area to remove NPS pollutants from waters passing through the wetland or riparian area. Acting as a sink for phosphorus and converting nitrate to nitrogen gas through denitrification are two examples of the important NPS pollution abatement functions performed by wetlands and riparian areas.
Restoration of wetlands and riparian areas is a holistic approach to water quality that addresses NPS problems while meeting the goals of the Clean Water Act to protect and restore the chemical, physical, and biological integrity of the Nation's waters. Full restoration of complex wetland and riparian functions may be difficult and expensive, depending on site conditions, the complexity of the system to be restored, the availability of native plants, and other factors. Specific practices for restoration must be tailored to the specific ecosystem type and site conditions.
3. Management Measure Selection
Selection of this management measure was based on:
- The localized increase in pollutant loadings that can result from the degradation of wetlands and riparian areas (Reinelt and Horner, 1990; Richardson, 1988);
- The nonpoint pollution abatement function of wetlands and riparian areas (Cooper, 1990; Cooper and Gilliam, 1987; Jacobs and Gilliam, 1985; James et al., 1990; Karr and Gorman, 1975; Lowrance et al., 1983; Lowrance et al., 1984; Peterjohn and Correll, 1984; 9Pinay and Decamps, 1988; Stuart and Greis, 1991); and
- The opportunity to gain multiple benefits through the restoration of wetland and riparian area systems, e.g., aquatic and riparian habitat functions for wildlife and NPS pollution reduction benefits (Atcheson et al., 1979; Mitsch and Gosselink, 1986).
Refer to Section II.A.3 of this chapter for additional information regarding the degradation, effectiveness, and multiple benefits of wetlands and riparian areas.
As discussed more fully at the beginning of this chapter and in Chapter 1, the following practices are described for illustrative purposes only. State programs need not require implementation of these practices. However, as a practical matter, EPA anticipates that the management measure set forth above generally will be implemented by applying one or more management practices appropriate to the source, location, and climate. The practices set forth below have been found by EPA to be representative of the types of practices that can be applied successfully to achieve the management measure described above.
- a. Provide a hydrologic regime similar to that of the type of wetland or riparian area being restored.
The following list identifies some important information or considerations to address in a restoration project.
- Site history - Know the past uses of the site, including past functioning as a wetland.
- Topography - Map the surface topography, including slope and relief of the existing land surface, and elevations of levees, drainage channels, ponds, and islands.
- Tide - Determine the mean and maximum tidal range.
- Existing water control structures - Identify the location of culverts, tide gates, pumps, and outlets.
- Hydrology - Investigate the hydrologic conditions affecting the site: wave climate, currents, overland flows, ground-water dynamics, and flood events.
- Sediment budgets - Understand the rates and paths of sediment inflow, outflow, and retention.
- Soil - Describe the existing soils, including their suitability for supporting wetland plants.
- Plants - Identify the existing and, if different, native vegetation.
- Salinity - Measure the existing or planned salt level at the site.
- Consider the timing of the restoration project and the duration of the construction schedule for installation activities.
- Assess potential impacts to the site from adjacent human activities.
Restoration of hydrology, in particular, is a critical factor to gain NPS benefits and to increase the probability of successful restoration.
- b. Restore native plant species through either natural succession or selected planting.
When consistent with preexisting wetland or riparian area type, plant a diversity of plant types or manage natural succession of diverse plant types rather than planting monocultures. Deeply rooted plants may work better than certain grasses for transforming nitrogen because the roots will reach the water moving below the surface of the soil. For forested systems, a simple approach to successional restoration would be to plant one native tree species, one shrub species, and one ground-cover species and then allow natural succession to add a diversity of native species over time, where appropriate and warranted by target community composition and anticipated successional development. Information on native plant species is available from Federal agencies (e.g., USDA-SCS or USDOI-FWS), or various State or local agencies, such as the local Cooperative Extension Service Office or State departments of agriculture or natural resources. Other factors listed below need to be considered in the implementation of this practice.
Type and Quantity of Pollutant. Sediment, nitrates, phosphates, and thermal pollutants are effectively reduced by riparian areas. Riparian forests can also effectively remove nitrates from ground water. Eroded materials and attached pollutants from upslope areas are trapped on the surface. Suspended sediments and attached pollutants are removed during inundation by floodwaters (Table 7-1).
Slope. Riparian forest water quality functions have primarily been studied on cropland watersheds where slope has not been a factor. While sheet flow is not required for effective removal of NPS pollution from runoff passing through a riparian area, concentrated flows must be dispersed before upland runoff enters the riparian area.
Vegetated Area. Nonleguminous hardwoods are the most effective vegetation for nitrate removal. Where shade is critical, taller conifers may be preferred. The vegetation should be managed to retain larger trees near streams and denser, more vigorous trees on the remainder of the area. Research has also shown that a naturally rough forest floor is effective in trapping sediment (Swift, 1986).
- c. Plan restoration as part of naturally occurring aquatic ecosystems.
States should factor in ecological principles when selecting sites and designing restoration. For example, seek high aquatic and riparian habitat diversity and high productivity in the river/wetland systems; look for opportunities to maximize connectedness (between different aquatic and riparian habitat types); and provide refuge or migration corridors along rivers between larger patches of uplands (animals are most likely to colonize new areas if they can move upstream and downstream under cover).
Planning to restore wetlands includes:
- Identifying sources of NPS problems;
- Considering the role of site restoration within a broader context, such as on a landscape basis;
- Setting goals for the restoration project based on location and type of NPS problem;
- Replicating multiple functions while still gaining NPS benefits; and
- Locating historic accounts (e.g., maps, descriptions, photographs) to identify sites that were previously wetland or riparian areas. These sites are likely to be more suitable for restoration if the original hydrology has not been permanently altered.
A few examples of wetland restoration are shown in Table 7-7.
5. Costs for All Practices
This section describes costs for representative activities that would be undertaken in support of one or more of the practices listed under this management measure. The description of the costs is grouped into the following two categories:
- A wetlands/riparian restoration project involving a low level of effort.
The items of work would include (a) clearing the site of fallen trees and debris; (b) application of seed stock or sprigging of nursery-reared plants; (c) application of fertilizer (most typically for marsh restoration); and (d) a minimal amount of postproject maintenance until the vegetation becomes established.
A low level of effort could also include minor adjustments to the existing hydrology, such as the installation of stop-logs to raise water levels, or improvements to the existing drainage patterns undertaken to lower water levels (e.g., pulling the plug on tile fields).
- A wetlands/riparian restoration project involving a high level of effort.
The items of work would include (a) clearing the site of fallen trees and debris; (b) extensive site work requiring heavy construction equipment; (c) application of seed stock or sprigging of nursery-reared plants; (d) application of fertilizer (most typically for marsh restoration); and (e) postproject maintenance and monitoring.
A high level of effort is distinguished from a low level by the amount of site work required. A high level of effort typically will require heavy construction machinery, including graders, bulldozers, and/or dump trucks. These pieces of equipment will be used to accomplish several tasks, such as:
- Adding additional fill material to the site or removing excessive amounts of on-site material;
- Realigning the existing on-site substrate to appropriate lines and grades as shown on the design plan; and
- Realigning existing channels or constructing new channels, diversions, basins, or tidal flats as necessary to restore preexisting surface water flow characteristics.
In addition to the need for heavy construction equipment to perform the work, a restoration project involving a high level of effort typically requires more extensive analysis and evaluation of the site before work is started. Site surveys and preparation of formal design drawings and specifications are frequently necessary prior to starting the work. Periodic site visits are needed to inspect the work in progress. Spot surveys are frequently necessary to check the lines and grades of new channels and wetlands planting areas as they are being formed with the heavy construction machinery. Finally, a high-level restoration frequently requires postproject monitoring and adjustment as water begins to flow through the recreated surface water systems in the restored wetland.
The costs for items of work associated with either a low level or a high level of effort are reported below from actual examples of recent projects involving wetlands and riparian area restoration. The cases cited are representative of the levels of effort that could be undertaken in support of the practices under Management Measure II.B.
Each of the following examples contains a description of costs as they are reported in the source document. For ease of comparison, these costs are converted to 1990 dollars, using conversion factors published in the Engineering News-Record. A full explanation of the conversion factors is contained in Table 7-8.
a. Costs for "Low-Level" Restoration Projects
The two sources of wetland and riparian plants that should be used in restoration projects are seed and nursery-reared plant stock. Transplantation of wetland plant materials from other natural ecosystems is not recommended, but transplantation of young trees and shrubs growing in upland areas for riparian area restoration is acceptable, provided no other suitable source of plant stock is available. Transplantation of wetland plants is not recommended because digging up existing wetlands for removal of plant material can cause serious disturbance and dislocation of healthy systems. In addition, pests, disease, and contaminants can be carried along with the transplants and introduced into the area undergoing restoration. For this reason, even though it is possible to locate citations in the literature for transplantation costs, they are not included in the list below.
- Costs for a 1982 tidal wetlands project in Chesapeake Bay, Maryland, included seeding and fertilizing salt marsh cordgrass at $204.85 per acre (Earhart and Garbisch, 1983).
Cost in 1990 dollars - $253.42/acre
- Costs reported in 1979 for tidal wetlands restoration in coastal California included seeding and fertilizing salt marsh cordgrass at $300 to $500 per acre (Jerome, 1979).
Cost in 1990 dollars - $470 to 780/acre
- Costs reported in 1992 for nontidal wetlands included purchasing and installing nursery-reared plant stock (emergents) at $2,024 to $2,429 per acre (Hammer, 1992).
Cost in 1990 dollars - $1,936 to 2,323/acre
- Costs reported in 1989 for bottomland forest restoration using direct seeding were $40 to $60 per acre (National Research Council, 1991).
Cost in 1990 dollars - $41.20 to $61.80/acre
- Costs reported in 1990 for nursery-reared tree seedlings were $212.50 per acre (Illinois Department of Conservation, 1990).
Cost in 1990 dollars - $212.50/acre
As this cost information indicates, nursery-reared plant materials used in nontidal wetland restoration projects are generally more expensive than plants used in restoration of tidal wetlands. This difference seems to be partly due to the greater ease with which tidal wetland plants can be grown in nurseries in sufficient quantities for commercial distribution.
The "law of supply and demand" is another factor influencing the price of these two types of items. Mitigation requirements for tidal wetlands have been imposed in many coastal regions of the United States since the mid-1970s, and the commercial market has responded by developing the methods to produce adequate quantities of nursery stock available at the appropriate planting seasons to meet the demand. The requirements for mitigation of nontidal wetlands have only more recently been enforced. Thus, in certain geographic areas of the United States, the demand for these kinds of plant materials from nurseries probably exceeds the supply, resulting in higher unit costs.
Two other factors that influence the costs of seed or plant stock are (1) using exotic or hybrid varieties or introduced species and (2) purchasing plant stock from properly certified and inspected nurseries. When considering the use of seeds or nursery stock for restoration projects, it is best to consider only strong, nonexotic strains of plant materials. Many nurseries carry exotic strains of common species, introduced species, or hybrid varieties. These types of plant stock are intended for use in the home watergarden or in landscaping projects. Always check the genus and species of the plants found in the natural wetland and riparian systems in the locality and insist on purchasing these same varieties from the nursery. In addition, several States have inspection and certification programs for nursery-reared plant stock. For example, the State of Maryland's Department of Agriculture publishes a Directory of Certified Nurseries, Licensed Plant Dealers, Licensed Plant Brokers (Maryland Department of Agriculture, 1990). Likewise, the Association of Florida Native Nurseries (AFNN) publishes an annual Plant and Service Locator (AFNN, 1989). In these cases, plants should always be obtained from properly inspected and certified dealers. In some regions of the United States, more stringent rules and regulations apply to plant stock purchased for transport across State lines. Such laws exist in part to minimize the potential for the spread of pests and disease and should be strictly adhered to.
Obtaining strains of plant material identical to those occurring in natural ecosystems, through properly certified and inspected plant dealers, frequently results in a slightly higher product cost. However, increased benefits in environmental protection and project performance will generally justify paying the slightly higher price.
b. Costs for "High-Level" Restoration Projects
Costs for projects involving extensive site work will vary widely based on several factors, including (1) the extent and complexity of the work shown on the design drawing, (2) the local availability of construction equipment, and (3) the degree of difficulty involved in gaining access to the site. In addition, as the examples of restoration projects listed below illustrate, overall project costs can be considerably increased if the land containing the proposed restoration project must be purchased before any work is undertaken.
In compiling the restoration costs for the examples listed below, the reported costs for riparian work were frequently presented in units of linear feet of streambank. For ease of comparison with the other examples, these costs were converted to dollars per acre by assigning a width along the streambank within which work is assumed to have taken place.
- Costs reported for the 1980 restoration of diked tidelands at the Elk River in Humboldt Bay, California, ranged from $5,000 to $7,000 per acre. The items of work included breaching of dikes to restore preexisting hydrology, construction of new dikes at a lower elevation, installation of other drainage controls, and restoration of tidal wetland vegetation (Anderson and Rockel, 1991).
Cost in 1990 dollars - $7,300 to $10,000/acre
- Costs reported for the 1986 restoration of tidal wetlands at three California coastal sites averaged $23,700 per acre. The sites included Big Canyon in Upper Newport Bay, Freshwater Slough, and Bracut (both in Humboldt Bay). Existing fill had to be removed from the sites before wetlands restoration could be accomplished (Anderson and Rockel, 1991).
Cost in 1990 dollars - $26,070/acre
- Costs reported for restoration of riparian areas in Utah between 1985 and 1988 were used to compute an average cost of approximately $2,527 per acre, assuming a streamside width of 100 feet for the work. The items of work included bank grading, installation of riprap and sediment traps in deep gullies, planting of juniper trees and willows, and fencing of the site (Nelson and Williams, 1989).
Cost in 1990 dollars - $2,527/acre