With winter comes the ice on many Montana lakes and reservoirs, tempting winter anglers to ice fish. Montana Fish, Wildlife & Parks cautions ice anglers that the build up of ice is not a predictable or dependable process. Even as ice firms up, it tends to melt as temperatures fluctuate. That means ice that was safe yesterday can become a death trap by tomorrow. Whatever the weather, it’s best to test ice before venturing onto it. The ice’s thickness depends on currents, inflows from streams, water depth, underwater springs and stumps or other features protruding through the ice, and daily temperatures. Slight changes in any one factor can significantly affect ice conditions from day to day. The best method to determine the thickness of ice is with an ice spud. Trusting the ice is solid because others have used it recently puts you at risk. If you test the ice yourself, you’ll know it is safe.