If any bill shall be enacted by the United States appropriating moneys to assist the states in protecting the health of mothers and children, and if the Department of Health and Social Services is doing such work at the time the federal aid becomes available, the Department of Health and Social Services shall designate and authorize to be spent such portion of its appropriation as may be necessary to meet the offer of the federal government, if the Department of Health and Social Services shall be recognized by the federal body administering the act as the state body with which it will cooperate. Only such an amount of the Department of Health and Social Services' appropriation may be designated and spent for the purposes described in this section as will leave at least $15,000 annually for the execution of the duties of the Department of Health and Social Services under this subchapter, other than those which conform with such a federal act which may be enacted.