Spring rains fill Flathead Lake

March was warm and wet in the Flathead Basin. Precipitation accumulation was 7.48 inches, 223 percent of normal and temperatures were 1.9 degrees warmer than normal. March’s water supply into the Flathead was monstrous, (297 percent of average as compared to historical data from 1981-2010). April looks to be very wet as well, with the water supply forecast currently 154 percent of normal. The current Snow Water Equivalent (SWE) for the Flathead is 109 percent of normal. For all intents and purposes, spring runoff has begun and it was earlier than expected. March’s ending lake elevation was 2,887.2 feet. The lake is filling and the project is being operated under channel restriction. Current inflow is 26,000 cubic feet per second (cfs) and outflow is approximately 23,200 cfs. By the end of April, the lake will have filled another foot. Refill will continue through May with an end target elevation of 2890 feet. The lake will be full by the end of June (between 2892.5 and 2892.9 feet) for summer recreation.