Before modern refrigeration, the ice harvest on freshwater ponds was a staple of Maine winters. Local ice went to use in homes, on fishing boats, and, of course, in making ice cream. Most icehouses eventually disappeared, but not Thompson Ice House. In 1826, Asa Thompson dammed a small brook in South Bristol and started harvesting ice. More than a century and a half later, his great-grandson donated the property to a nonprofit organization that today operates a tiny museum, and once a year, still hosts a harvest. Volunteers saw off chunks of ice and float them to the icehouse, where more volunteers use pike poles to stack the 300-pound blocks. This year’s harvest, complete with hot chocolate and chili for visitors, is scheduled for February 19 — and some of that ice will then end up making ice cream for a social in July.