The board of county commissioners, with the approval of the tax commissioner, may abate any assessments made by irrigation districts if application therefor is approved by the board of the irrigation district. In case such assessments are made for the purpose of meeting payments due to the United States or any department or agency thereof or to the state water commission, the application shall not be granted unless it also bears the approval of an authorized representative or agent of the United States or of such department or agency, or of the state water commission, as the case may be. In case bonds or improvement warrants are deposited with a trustee under a trust agreement or trust indenture, the consent of such trustee shall be obtained before abating any assessment for such bonds or improvement warrants. The application for the abatement may be made by the board of the irrigation district instead of by individual taxpayers and any number of tracts of land may be included in a single application.