Idaho Code § 43-306
Any irrigation district now organized, or which may hereafter be organized, under the laws of the state of Idaho, shall have authority to construct drainage works for the purpose of draining, or reclaiming, any land, or lands, within such irrigation district, which authority shall be exercised by the board of directors in its discretion.
The board of directors before levy as hereinafter provided, shall determine by resolution spread on the minutes thereof if any of the lands within an irrigation district are in need of drainage, and should be drained to protect said land or other lands within said district from damage from seepage or other waters, subterranean or otherwise, then the board of directors of such district shall have the power and authority, at the time provided by law for levying assessments for the operation and maintenance of said irrigation district in addition to such assessments, to also levy an assessment against the lands of said irrigation district for drainage purposes, said levy not to exceed in any one (1) year forty per cent (40%) of the total amount levied for operation and maintenance purposes. Such assessment for drainage shall in all respects be levied and collected at the same time and in the same manner as assessments for operation and maintenance.
All funds collected for drainage purposes under the provisions hereof shall be kept in a separate fund to be known as "Drainage Fund" of said irrigation district, and the moneys in said "Drainage Fund" from time to time may be expended by the board of directors of said irrigation district.
Idaho Code § 43-306