Whenever (1) a school district that is not a member of a learning community suffers a reduction in the taxable valuation of the real property within the district by reason of the purchase or appropriation by the United States or any instrumentality of the United States of land in the district for any defense, flood control, irrigation, or war project, (2) the number of children who are five through twenty years of age residing in the district increases by reason of the use by the United States of the land so purchased or appropriated for such purposes, and (3) such increase in the number of pupils who will be eligible to attend school in the district does or will require a levy of taxes for general school purposes in excess of the average levy for general school purposes of school districts of the same class in the county, the State Committee for the Reorganization of School Districts shall change the boundaries of the existing district to exclude all land purchased and appropriated by the United States and all land which by reason of its use or ownership is exempt from state taxation under the United States Constitution and the statutes of the United States. When the United States, by the appropriate officer, does not accept or has not accepted exclusive jurisdiction over land so excluded, the state committee shall form a new school district embracing land thus excluded.