Environment

IDOT maintains approximately 60,000 bridges over streams and rivers. During the construction or rehabilitation of bridge structures, IDOT must comply with the Clean Water Act, the National Environmental Policy Act (NEPA), the Fish and Wildlife Coordination Act, and other related laws and regulations. To comply with these regulations IDOT conducts environmental surveys. These field surveys range from the identification of federal and state listed endangered and threatened species to the characterization of the physical (substrate), biological (fish, mussels, aquatic macroinvertebrates), and chemical (concentrations of heavy metals, chloride, dissolved oxygen) components of streams. The results of these surveys are used to obtain permits (section 404 and 401 of the Clean Water Act) from the Corps of Engineers, Illinois Environmental Protection Agency (IEPA) and/or to meet the requirements of NEPA.

IDOT looks at rivers on the National Wild and Scenic River System and the Nationwide Rivers Inventory and coordination may occur for work on these streams with the National Park Service. IDOT uses IEPA Illinois Integrated Water Quality Report and Section 303(d) List to determine streams or lakes water quality standards, the designated uses of these water bodies, and the IEPA assessment of these uses.

Highways may impact water quality through storm water runoff. IDOT is involved in activities to control and reduce contamination from highway runoff (see Storm Water Management Program on this website). Deicing materials used for snow and ice removal flow into area streams via roadside ditches and/or storm sewers. In addition, a portion of road salt that remains on the pavement may be dispersed into the air due to the motion of traffic. In order to analyze atmospheric dispersal of salt, IDOT, in conjunction with the Illinois State Tollway Authority and the Federal Highway Administration initiated studies that were performed by the Illinois Water Survey.

• Atmospheric Dispersion Study of Deicing Salt Applied to Roads: First Progress Report
• Atmospheric Dispersion Study of Deicing Salt Applied to Roads: Final Report

The 1987 Illinois Groundwater Protection Act was implemented to protect groundwater resources from degradation. The Act allows for the establishment of both regulated groundwater recharge areas and groundwater protection areas. For transportation projects groundwater is assessed in terms of recharge areas to identify the potential for proposed highway corridors to contaminate shallow aquifers. Groundwater studies using monitoring wells are often performed in areas that are considered sensitive because they support plant communities containing endangered or threatened species or land areas that have been designated as Natural Areas or Nature Preserves. Potential impacts to these resources can involve interruption and/or change in groundwater flow patterns. Areas featuring karst topography are especially subject to groundwater contamination because these areas do not contain the usual filtering layers provided by soil so that surface water contamination can flow directly into the groundwater.

An aquifer is an area containing saturated (with groundwater) soils and geologic materials that are sufficiently permeable to readily yield economically useful quantities of water to wells, springs, or streams under ordinary hydraulic gradients. A sole-source aquifer is one which supplies at least 50 percent of the drinking water consumed in the overlying area with no practicable alternative drinking water source. While Illinois has no designated sole-source aquifer at the present time, it has many shallow (sand and gravel) and deep (bedrock) aquifers. Public well water supplies are regulated through set back zones established by IEPA.

Every two years the IEPA issues an “Illinois Integrated Water Quality Report and Section 303(d) List”. Information on groundwater standards and groundwater quality can be found in this report.

Floodplains are areas of land that could be inundated by floodwaters from any source. Floodplains usually occur adjacent to streams, rivers, and lakes. Transportation projects are assessed for the potential for impacts to floodplains, more specifically encroachments into the 100-year floodplain. The 100-year floodplain is defined as an area that has a 1 percent or 1 chance in 100 of experiencing a flood condition that exceeds any previous 1 year period. Coordination with the U.S. Army Corp of Engineers and the Department of Natural Resources Office of Water Resources (IDNR-OWR) is required to obtain the necessary permits for work within floodplains. A regulated floodway is the channel of the stream plus any adjacent floodplain areas. These areas must be kept free of encroachment so that the 1 percent chance annual flood can occur without substantial increases in flood heights. Depending upon the location of the regulated floodplain, the regulatory authority may be the community within which the floodway is located, FEMA or IDNR-OWR. Bridge structures located over major rivers such as the Mississippi must be coordinated with the U.S. Coast Guard to ensure that pier placement does not affect shipping channels.

IDOT assesses potential impacts to wildlife and their habitats while planning and designing transportation facilities. To comply with the National Environmental Protection Act and other state and federal environmental laws and regulations, special studies and assessments are conducted, and coordination with state and federal natural resource agencies is initiated. Project impacts to wildlife are identified and evaluated and consideration is given to implementing practical measures to avoid, minimize, and mitigate any adverse impact to these valuable resources. To accommodate wildlife connectivity and to increase safety to the motoring public, IDOT includes wildlife crossing structures such as underpasses, culvert extension, and fencing within project designs in environmentally sensitive locations that feature quality habitat. These measures not only reduce wildlife mortality and the number of vehicle-animal collisions but help to ensure that species populations remain viable. In addition, IDOT considers effects on area sensitive migratory birds during project development and evaluates the potential for habitat fragmentation.

IDOT is one of many state and local agencies, and environmental groups involved in the “Illinois Wildlife Action Plan.” This initiative was developed to address the particular needs of wildlife species in an effort to stabilize and reverse trends in declining populations. The plan can be accessed here.

Other sources of information about this topic include:

• The 2006 publication “Eco-Logical: An Ecosystem Approach to Developing Infrastructure Projects” is a guide for making infrastructure more sensitive to wildlife and ecosystems through greater interagency cooperation. More information on the “Eco-Logical” approach can be found here.
• “The North American Breeding Bird Survey” is a major landscape-level survey of the birds of North America. It is an on-going cooperative program sponsored jointly by the U.S. Fish and Wildlife Service and the Canadian Wildlife Service. The main purpose of this roadside survey is to estimate population trends of the many species of birds that nest in North America and migrate across international boundaries. More information can be found on the U.S. Fish & Wildlife Service website or the North American Breeding Bird Survey page.
• The Illinois Natural History Survey website contains extensive information regarding all aspects of vertebrate and invertebrate species in Illinois. The “Inventory of Resource Rich Areas,” a watershed based land cover survey that identifies areas within the state that contain high quality habitat such as large tracts of woodlands and nearly one-half of the remaining wetlands can be found on the Illinois Natural History Survey Research webpage.
• Information regarding wildlife – vehicle collisions can be found on the Deer Vehicle Crash Information Clearinghouse webpage. This national study details the causes and impacts to wildlife-vehicle collisions. The site is a deer crash information clearinghouse that contains accident data and suggested countermeasures and strategies to reduce the number of deer-vehicle accidents.

Under the Endangered Species Act of 1973 and the Illinois Endangered Species Act, IDOT is required to consult with the U.S. Fish and Wildlife Service (U.S. FWS) and the Illinois Department of Natural Resources (IDNR) to insure that the department’s projects are not likely to jeopardize the continued existence of any endangered and threatened species (listed species). IDOT Division of Highways, Bureau of Design and Environment (BDE) procedures for consulting with the U.S. FWS and IDNR on these two Acts are detailed in Chapters 26 (section 26-9) and 27 (section 27-1) of the BDE manual.

The department utilizes in-house expertise together with other sources of geographic information to screen project areas for the presence of habitats that may contain or be suitable for a listed species. In the event a listed species is present or there is suitable habitat within a project area, IDOT will conduct surveys through a statewide contract with the Illinois Natural History Survey (INHS) to determine the continued presence of the species and suitable habitat in the area which aids the department in avoiding impacts, minimizing impacts, and as a last case scenario mitigating impacts. More information can be found on the INHS website.

There are occasions where the department will request INHS through the statewide contract to conduct surveys throughout the state or a specific region to gather more data to further streamline consultation with the agencies. One example of that is the survey work performed in District 1 for the Indiana bat. More information can be found under the Indiana Bat (below).

Further Information

• Illinois Endangered Species Act of 1971
• Federal Endangered Species Act of 1973
• Interagency Cooperation—Endangered Species Act of 1973, as Amended, Subpart B, Consultation Procedures (50 CFR Part 402)
• Consultation Procedures for Assessing Impacts of Agency Actions on Endangered and Threatened Species and Natural Areas (17 Ill. Adm. Code Part 1075)
• Incidental Taking of Endangered or Threatened Species (17 Ill. Adm. Code Part 1080)
• Memorandum of Understanding between IDNR and IDOT

Web Links

• Bureau of Design and Environment Manual

Background

IDOT complies with Section 404 of the Clean Water Act (CWA) and the Illinois Interagency Wetland Policy Act of 1989 (IWPA). Departmental procedures for ensuring compliance with the CWA and IWPA are detailed in the IDOT Wetlands Action Plan, Bureau of Design and Environment Manual, Chapter 26-8. Under the CWA and IWPA, IDOT must demonstrate that all measures were taken to first avoid and then minimize impacts to wetlands to the fullest extent practicable. Unavoidable impacts are mitigated by way of wetland compensation through either restoration or creation of wetlands.

IDOT. The INHS and Illinois State Geological Survey provide technical assistance to IDOT in locating, evaluating and monitoring compensatory wetlands. More information on the Wetlands Group can be found on INHS’s Wetland Science Program webpage.

Wetland Mitigation Bank Sites

The link below will provide electronic copies of base-line studies, instruments and monitoring reports for IDOT bank sites and multi-use compensation sites.

IDOT Wetland Mitigation Bank Sites

Further Information

• Illinois Wetland Restoration and Creation Guide
• Compensatory Mitigation for Losses of Aquatic Resources; Final Rule
• 2010 FHWA Exemplary Ecosystem Initiative – Nomination Submittal for North Chicago
• IDOT Wetlands Action Plan April 15, 1998

Web Links

• Illinois Inter-agency Wetland Policy Act of 1989
• 1987 Corps of Engineers Wetlands Delineation Manual
• Bureau of Design and Environment Manual

Please navigate to Roadside Maintenance to view more information.

In 1956, the Illinois Department of Transportation established a policy for the preservation of cultural properties found in proposed highway rights-of-ways and currently partners with the Illinois State Archaeological Survey (ISAS) for specialized services, such as archaeological surveys and excavations, field work and reports and documentation to name a few.

IDOT partners with the Illinois State Archaeological Survey (ISAS) to maintain Historic Bridge Survey inventories to maintain an inventory of the State's Historic Bridges, which are at least fifty years old and of historical significance. 

IDOT Guidance for Photographing Historic Structures

In the years since the National Environmental Policy Act was signed into law in 1970, the range of concerns about the relationship between the highway and its associated effects on the surrounding environment has expanded. The approach of sustainability and I-LAST is to incorporate a broader range of issues into the development and completion of state highway projects.

This document is titled Illinois Livable and Sustainable Transportation (I-LAST) Rating
System and Guide and is a sustainability performance metric system developed by the Joint
Sustainability Group of the Illinois Department of Transportation (IDOT), the American Council of Engineering Companies (ACEC) and the Illinois Road and Transportation Builders Association (IRTBA). The intent is that this rating system and guide will be revised as the state of the art evolves – utilizing the input of industry users.

Community Impact Assessment (also referred to as Socio-economic Assessment) is a process used to evaluate the effects of transportation projects on community residents and their quality of life. Typically these effects may include changes in access, business and residential relocations, environmental justice issues, cohesion impacts, affects on public facilities and services, development and growth patterns, land use changes and other potential results associated with improvements in infrastructure. The assessment process is an integral part of project planning and development. Public involvement during the early stages of project development can ensure that the community residents are not only aware of the planned improvement but play an active role in achieving the greatest possible benefit for the most people. These processes are in place to facilitate beneficial results for the community.

IDOT’s Community Impact Assessment Manual has been developed for use in the identification and assessment of socioeconomic impacts. This manual provides a description of the community impacts that may occur as a result of a transportation project, and specifies methods, techniques and data requirements for conducting a community study. Also included are procedures for presenting the results of the assessment in environmental documents and a description of mitigation measures that can be applied if adverse impacts are unavoidable.