The amount of salt brine used on Iowa's 9,400 miles of state and interstate highways has more than tripled during the past decade, rising from about 4.6 million gallons in 1998-99 to 15.3 million gallons last winter, said Dennis Burkheimer, winter operations administrator for the DOT. The growth is a reflection of expanded use of salt brine statewide.The 15.3 million gallons last winter was applied to roads before winter storms and on bridge decks when frost was forecast.

The figure also includes salt brine sprayed on dry rock salt before it was spread during storms to jump-start melting. Brine also helps rock salt stick to pavement, reducing the amount blown away or swept to the roadside.