https://chroniclingamerica.loc.gov/lccn/sn85038531/1918-04-30/ed-1/seq-1/

Ice is the latest product to be in short supply. Government has imposed restrictions on the use of ammonia to develop artificial (as opposed to blocks cut from lakes) ice. Prohibition laws continue to reduce the availability of alcohol as New Hampshire ends sales. 

Source: "Possibility of Serious Ice Shortage Foreshadowed," Chattanooga News, Chattanooga, Tennessee, April 30, 1918. Page 1, Column 3.