glare

adjective, N. Amer., (esp. of ice) smooth and glassy (COD)

“If the ice was good and glare, it wouldn’t take long [to cross the lake], but sometimes it would be deep slush.”

“Was there a specific area where you guys would get the best ice?”
“Well, wherever it was glare, eh? Up there, sometimes it come in rough, and we had to put it in the spot where it was glare. Clear blue ice. No snow in it.”