On September 28, 1931, the United States Department of Commerce told the CFA that the tall columns were a risk to aviation. The Commerce Department said that the columns would seriously interfere with air traffic using Hoover Field, and demanded that the CFA either eliminate the columns or floodlight them brightly. The Washington Board of Trade added its opposition to the columns on September 29. Grant agreed that, should an investigation show a hazard, the columns would have to be eliminated. The CFA agreed that street lights should be placed alongside the roads on Columbia Island both as an aid to vehicular traffic and as a means of warning air traffic. But the CFA was adamantly opposed to floodlighting the memorial columns, for they would compete with the softer lighting illuminating the Lincoln Memorial and Arlington House in Arlington National Cemetery. William Kendall, however, was so adamant about retaining the memorial columns that he personally wrote President Hoover (who technically chaired the AMBC) in early October 1931 outlining his reasons for keeping the columns and telling Hoover to move the airport if they interfered with flight.