23 CFR § 777.9 - Mitigation of impacts.
(a) Actions eligible for Federal funding. There are a number of actions that can be taken to minimize the impact of highway projects on wetlands or natural habitats. The following actions qualify for Federal-aid highway funding:
(1) Avoidance and minimization of impacts to wetlands or natural habitats through realignment and special design, construction features, or other measures.
(2)Compensatory mitigation alternatives, either inside or outside of the right-of-way. This includes, but is not limited to, such measures as on-site mitigation, when that alternative is determined to be the preferred approach by the appropriate regulatory agency; improvement of existing degraded or historic wetlands or natural habitats through restoration or enhancement on or off site; creation of new wetlands; and under exceptional circumstances, preservation of existing wetlands or natural habitats on or off site. Restoration of wetlands is generally preferable to enhancement or creation of new wetlands.
(3) Improvements to existing wetlands or natural habitats. Such activities may include, but are not limited to, construction or modification of water level control structures or ditches, establishment of natural vegetation, re-contouring of a site, installation or removal of irrigation, drainage, or other water distribution systems, integrated pest management, installation of fencing, monitoring, and other measures to protect, enhance, or restore the wetland or natural habitat character of a site.
(4) Mitigation banks. In accordance with all applicable Federal law (including regulations), with respect to participation in compensatory mitigation related to a project funded under title 23, U.S. Code, that has an impact on wetlands or natural habitat occurring within the service area of a mitigation bank, preference shall be given, to the maximum extent practicable, to the use of the mitigation bank, if the bank contains sufficient available credits to offset the impact and the bank is approved in accordance with the Federal Guidance for the Establishment, Use, and Operation of Mitigation Banks, or other agreement between appropriate agencies.
(b) Mitigation banking alternatives eligible for participation with Federal-aid funds including such measures as the following:
(1)Mitigation banks in which mitigation credits are purchased by State DOTs to mitigate impacts to wetlands or natural habitats due to projects funded under title 23, U.S. Code, including privately owned banks or those established with private funds to mitigate wetland or natural habitat losses.
(2) Single purpose banks established by and for the use of a State DOT with Federal-aid participation; or multipurpose publicly owned banks, established with public, non-title 23 Federal highway funds, in which credits may be purchased by highway agencies using title 23 highway funds on a per-credit basis.
(c) Contributions to statewide and regional efforts to conserve, restore, enhance and create wetlands or natural habitats. Federal-aid funds may participate in the development of statewide and regional wetlands conservation plans, including any efforts and plans authorized pursuant to the Water Resources Development Act of 1990 (Pub. L. 101-640, 104 Stat. 4604). Contributions to these efforts may occur in advance of project construction only if such efforts are consistent with all applicable requirements of Federal law and regulations and State transportation planning processes.
(d) Mitigation or restoration of historic impacts to wetlands and natural habitats caused by past highway projects funded pursuant to title 23, U.S. Code, even if there is no current federally funded highway project in the immediate vicinity. These impacts must be related to transportation projects funded under the authority of title 23, U.S. Code.