For the purpose of this chapter:

(1) The term “Committees” means the Committee on Merchant Marine and Fisheries and the Committee on Natural Resources of the House of Representatives and the Committee on Environment and Public Works and the Committee on Energy and Natural Resources of the Senate.

(2) The term “designated unit” means a unit of the National Wildlife Refuge System designated by the Secretary under section 3911(a)(2) ¹ of this title.

(3) The term “hydric soil” means soil that, in its undrained condition, is saturated, flooded, or ponded long enough during a growing season to develop an anaerobic condition that supports the growth and regeneration of hydrophytic vegetation.

(4) The term “hydrophytic vegetation” means a plant growing in—

(A) water; or

(B) a substrate that is at least periodically deficient in oxygen during a growing season as a result of excessive water content.

(5) The term “wetland” means land that has a predominance of hydric soils and that is inundated or saturated by surface or groundwater at a frequency and duration sufficient to support, and that under normal circumstances does support, a prevalence of hydrophytic vegetation typically adapted for life in saturated soil conditions.