Despite the time and expense, it is an economic and environmental necessity. The Definitive Guide to the Practice of Wetland IdentificationThe second edition of the bestselling Practical Handbook for Wetland Identification and Delineation offers solutions to real-world problems in the scientific and regulatory aspects of wetlands. The authors present characteristics and indicators of wetlands that are the focus of the jurisdictional issue, and discuss strategies and methods for making wetland identifications and delineations that meet federal requirements.
Low and higher altitude aerial imagery, geographic information system GIS databases, easily accessible land cover maps, and fine resolution satellite data are just a few of the resources available. In spite of these advances, it is still difficult to find practical directions on how to gather needed data in the literature. WES originally conceived of a two-volume manual: Volume I would specify criteria for hydrology, vegetation, and soils; Volume H would describe methods and procedures for delineation.
Because of internal disagreements over this draft, it was held in draft form while WES continued to work on Volume H.
By John G. Lyon Lynn Krise Lyon - John G. Lyon Lynn Krise Lyon
Ultimately, the two-volume draft manual was combined into a single volume that was reviewed within USACE in and The final product was published in January as the U. It also gave instructions on the exercise of professional judgment for atypical situations. The result was the interagency manual Federal Interagency Committee for wetland Delineation, , which was subsequently withdrawn from use.
The federal government then proposed revisions to the manual in When the interagency manual was withdrawn, and while proposed revisions were pending, USACE continued to use its Corps manual. In fact, Congress directed that USACE follow the Corps manual and that landowners who had delineations made under the interagency manual be given the opportunity to revise them according to the Corps manual Energy and Water Development Appropriation Act of , P.
EPA began developing its manual with the issuance in of interim guidance for the identification of wetlands. In , the rationale and guidance were revised and expanded, and a draft manual was prepared. A revised draft was prepared and circulated again in for agency and external review.
After field testing and modification in response to review, the manual was published. The EPA manual, however, allows delineators to rely on vegetation alone for routine delineations and when obligate wetland or upland species are dominant. According to the manual, soils and hydrology must be evaluated if the vegetation is not dominated by obligate wetland or upland species. The manual describes the difficulties of using hydrologic indicators for delineating wetland boundaries, and it justifies the heavier reliance on soils and vegetation in terms of these difficulties.
These approaches are analogous to the Corps manual's ''routine approach" and ''comprehensive approach. The detailed approach requires greater quantification of the composition of vegetation and an examination of soils and hydrology. Similarly, the manual requires a more detailed examination for atypical or disturbed areas. Shortly after EPA published its manual, it collaborated in publishing the interagency manual.
After the interagency manual was withdrawn and its proposed revisions were developed, EPA announced that it would follow the Corps manual 58 Fed. The third edition incorporates changes that implement the MOA, although some important components were still under development when it was released. Part of the NFSAM describes the preparation for wetland determinations; part describes the procedures for wetland determinations. Indicators for field delineation are given in part The NFSAM requires that, for agricultural lands, three factors—hydric soils, hydrology, and hydrophytic vegetation—be assessed independently.
Under the terms of the FSA, farmers must obtain a wetland delineation before NRCS determines whether their lands qualify for statutory exemptions or exclusions. NRCS will perform wetland delineations at the request of a farmer. Some areas that would otherwise qualify as wetlands are exempt from NRCS-administered programs. These include artificial wetlands on farmland that was cropped before Dec.
NRCS determines whether an exclusion applies and, if so, marks the excluded areas.
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NRCS wetland delineation is valid for 5 years unless new information warrants a revision. Office determinations are based on review of at least three aerial photographs, soil surveys, and other determinations previously made for the property Chapter 8. In practice, field determinations are done only when a farmer appeals an office determination. These classes relate to the kinds of farming activities that are allowed or prohibited on farmed wetland—areas that were drained or otherwise manipulated before Dec. A farmed wetland that is a playa, pothole, or pocosin must be inundated for at least 7 consecutive days or saturated for at least 14 consecutive days during the growing season.
NFSAM specifically acknowledges that these especially restrictive guidelines are intended to protect the unique wetland functions of potholes, playas, and pocosins. Wetland used for pasture or forage production, but not permanently drained or altered, qualifies as fanned wetland. The hydrologic thresholds for fanned wetland pasture require inundation for at least 7 consecutive days or saturation for at least 14 consecutive days during the growing season.
NRCS did not, however, formally adopt the interagency manual because it has its own regulations. As mentioned in Chapter 3 , after the interagency manual was criticized, the Bush administration proposed a revised delineation manual proposed revisions, 56 Fed. It initially announced that the interagency manual would remain in effect pending adoption of revisions. NRCS has continued to use. NFSAM and its own regulations. The proposed revisions, which followed the interagency manual, also generated considerable public and serious scientific criticism.
The controversy resulted in continued use of the Corps manual, and a congressional mandate that the National Academy of Sciences conduct a study, as described in Chapter 1. Table 4.
Each manual applies a three factor definition of wetland, yet each does so differently. Many of the differences among the manuals seem minor, but they can be significant in the field. The Corps manual gives criteria and lists indicators for hydrology, hydric soils, and hydrophytic vegetation. Delineators must test hydrology, vegetation, and soils, but indirect indicators may be used to show that criteria are satisfied.
Only for routine determinations affecting an area of less than 5 acres about 2 ha and in special cases, such as disturbed wetlands where vegetation has been removed, can evidence on specific criteria be omitted, however. The Corps manual is supplemented with USACE guidance letters and memoranda addressing specific issues pertinent to wetland delineation. The interagency manual allows somewhat greater latitude in the use of indicators. For example, if hydric soils and wetland hydrology are present, a delineator can assume that the vegetation is hydrophytic.
Similarly, if the hydrology is unaltered, wetland hydrology can be inferred from hydric soils or from characteristics of vegetation plant adaptation to recurrent inundation or saturation for routine and intermediate level determinations but not for comprehensive determinations. The proposed revisions require strict proof of hydrology, vegetation, and soils with separate field evidence. For example, hydrophytic vegetation or hydric soils cannot be used as indicators of hydrology. Show each separately; use fewer than three only for special cases disturbed sites or very strong evidence of two.
NFSAM requires independent assessment of hydric soil, hydrology, and hydrophytic vegetation. Because few NFSAM delineations are done in the field, however, it can be misleading to compare NFSAM's field requirements with those of the other manuals that require field delineations. NFSAM also incorporates by reference the field office technical guides, which provide specific information.
The manuals differ in their treatment of hydrology, as shown in Tables 4. The Corps manual establishes saturation thresholds as a percentage of growing season, which is defined by frost-free days. The manual also lists classes of hydrologic regimes that range from permanently inundated to intermittently or never saturated. The manual requires that saturation be to the surface. The surface can be dry, however, even though an area is considered saturated to the surface, because the critical water table depth is 12 in. The rationale is that capillary action saturates the upper surface of the soil above.
Inundation at surface 15 days; saturation at surface 21 days during growing season. Inundation at surface for 15 days for most areas; 7 days for potholes, playas, or pocosins. Consider other factors precipitation, stratigraphy, topography, soil permeability, plant cover.
Minimum 15 days of inundation, 21 days of saturation to surface during growing season. The interagency manual requires soil saturation or inundation to the surface for a fixed number of days rather than for a percentage of the growing season; critical depth is allowed to differ with soil type. The interagency manual notes that water is the overriding influence on vegetation and soils because of anaerobic conditions that occur when soil is saturated with water.
Unlike the other manuals, NFSAM applies hydrologic thresholds separately to each of its wetland classes; thresholds can differ among classes. All of the manuals allow the wetland hydrology criterion to be satisfied by specific indicators, some of which do not involve data on water Table 4. Each manual, however, treats hydrology and its indicators differently. Only the proposed revisions divide the indicators into primary indicators, which are sufficient to determine wetland hydrology, and secondary indicators, which require some type of corroborative evidence.
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