For the purposes of this chapter, the following terms shall mean:

The “Secretary”—the Secretary of Agriculture of the United States.

“Works of improvement”—any undertaking for—

(1) flood prevention (including structural and land treatment measures),

(2) the conservation, development, utilization, and disposal of water, or

(3) the conservation and proper utilization of land,

in watershed or subwatershed area not exceeding two hundred and fifty thousand acres and not including any single structure which provides more than twelve thousand five hundred acre-feet of floodwater detention capacity, and more than twenty-five thousand acre-feet of total capacity. No appropriation shall be made for any plan involving an estimated Federal contribution to construction costs in excess of $25,000,000, or which includes any structure which provides more than twenty-five hundred acre-feet of total capacity unless such plan has been approved by resolutions adopted by the appropriate committees of the Senate and House of Representatives: Provided, That in the case of any plan involving no single structure providing more than 4,000 acre-feet of total capacity the appropriate committees shall be the Committee on Agriculture, Nutrition, and Forestry of the Senate and the Committee on Agriculture of the House of Representatives and in the case of any plan involving any single structure of more than 4,000 acre-feet of total capacity the appropriate committees shall be the Committee on Environment and Public Works of the Senate and the Committee on Public Works and Transportation of the House of Representatives, respectively. Each project must contain benefits directly related to agriculture, including rural communities, that account for at least 20 percent of the total benefits of the project. A number of such sub­watersheds when they are component parts of a larger watershed may be planned together when the local sponsoring organizations so desire.

“Local organization”—any State, political subdivision thereof, soil or water conservation district, flood prevention or control district, or combinations thereof, or any other agency having authority under State law to carry out, maintain and operate the works of improvement; or any irrigation or reservoir company, water users’ association, or similar organization having such authority and not being operated for profit that may be approved by the Secretary; or any Indian tribe or tribal organization, as defined in section 5304 of title 25, having authority under Federal, State, or Indian tribal law to carry out, maintain, and operate the works of improvement.