Wetlands & Preliminary Studies Group

        The members of the wetlands and preliminary studies group perform wetland delineations for Illinois Department of Transportation (IDOT) proposed highway widening, realignment, and bridge replacement projects.  Wetland delineation procedures are prescribed under the 1987 Army Corps of Engineers Wetlands Delineation Manual.  Using a variety of maps and aerial photographs in conjunction with the local soil survey, we determine whether the site meets the hydric soil, wetland hydrology, and hydrophytic vegetation criteria for wetlands required by the 1987 manual.  It is also our duty to conduct site assessment and post-construction monitoring for IDOT wetland restoration and creation projects throughout the state.  We provide public service by speaking to various school and interest groups and presenting workshops about our work.  Some of us also conduct independent research related to wetlands and their functions.

Personnel:

Hydric Soils

Wetland Hydrology

Hydrophytic Vegetation

        Hydrophytic vegetation is defined as the sum total of macrophytic plant life that occurs in areas where frequency and duration of inundation or soil saturation are sufficient to exert a controlling influence on the plant species present.  The primary indicator of hydrophytic vegetation is:  more than 50% of the dominant species are OBL, FACW, FAC+, or FAC on lists of plant species that occur in wetlands.  Other indicators of hydrophytic vegetation include, but are not limited to: visual observation of plant species growing in areas of prolonged inundation and/or soil saturation, morphological adaptations, technical literature, physiological adaptations, and reproductive adaptations.  For links to many good plant information sites, click here.

Wetland Restoration and Creation

        Wetlands are an essential feature of the Illinois landscape.  The state supports a variety of wetland types, including wet prairie, marshes, floodplain forests, and swamps.  Prior to European settlement, these wetlands covered at least 23% of the surface area of the state, an estimated 3.3 million hectares (8.2 million acres).  Over the past two hundred years, however, wetlands have been drained, cleared, filled, polluted, and modified to accommodate the demands of human settlement.  As a result, wetland acreage has been decimated.  By the 1980's, only 371,414 hectares (917,765 acres) of the state's original wetlands (2.6% of the state's surface area) remained, and many of the remaining wetlands have been degraded by sedimentation and other forms of pollution.
        But wetlands have also been recognized as a valuable resource.  The functions of wetlands are many, including flood flow alteration, sediment stabilization, nutrient removal, production export, and biological diversity.  While the consequences of losing wetlands have not been thoroughly studied, awareness of the benefits wetlands provide has led to efforts to restore and rebuild Illinois' wetland resource.  In general, wetland restoration means the re-establishment of a wetland in the landscape where a wetland existed historically.  Wetland creation describes construction a wetland where none has occurred.
        In addition, the regulatory community has acknowledged the importance of wetlands and has created a setting for wetland protection.  Section 404 of the Clean Water Act of 1972 prohibits the deposit of dredge and fill materials into waters of the United States, including wetlands.  The U.S. Army Corps of Engineers (USACE) administer Section 404 regulations for development projects subject to this section.  The permitting process requires that mitigation procedures be followed in order to avoid or minimize wetland impacts.  When wetlands are destroyed, their loss must be compensated, primarily through restoration or creation.
        The current emphasis in wetland restoration and creation is to attempt to replicate natural wetland structure and function according to selected ecological principles.  Restoration continues to promise the greatest potential for success.  The art and science of ecological wetland restoration and creation, however, is still relatively new and the technology incomplete.  Many attempts to replicate natural function and form have not been successful.  Even "successful" restored or created wetlands do not fully replace the functions or biological and chemical features that have evolved in natural wetlands throughout many years.  It is extremely important to promote sound science to restore and create systems that function as and closely resemble natural wetlands.
        In order to advance this goal, INHS, in cooperation with the Illinois State Geological Survey and funded by the Illinois Department of Natural Resources and the Illinois Department of Transportation, published a guidebook to assist wetland managers in accomplishing this task.  The Illinois Wetland Restoration and Creation Guide is intended to direct the development and implementation of wetland restoration and creation projects.  This guidebook comprises six chapters that correspond to stages in the wetland restoration or creation process:  planning, assessment, design, construction, monitoring, and management.  Because conditions affecting planned wetland projects vary on an individual basis, exact specifications are not provided.  Users will need to select procedures that are applicable to their particular project of each stage and should consult natural resources professionals before undertaking unfamiliar procedures.  Each chapter essentially can be used independently, and wetland designers and managers are encouraged to use appropriate sections of this document as a reference in the field.  The Guide also includes an extensive set of appendixes that contain useful supplementary resources for wetland restoration and creation in Illinois.
        The Illinois Wetland Restoration and Creation Guide  (Special Publication 19) and other INHS wetlands-related special publications are available.  Please refer to the Publications Catalog for ordering information.