Water levels in the Great Lakes, which reached historic lows earlier this year, have recovered substantially because of heavy snowfall and spring rains, government scientists said. Lakes Michigan and Huron saw a 20-inch rise this year—nearly twice the normal amount, said Keith Kompoltowicz, who monitors the lakes for the Army Corps of Engineers. Levels remain below long-term averages in some of the lakes, and it is hard to predict whether the gains will hold, said Drew Gronewold, a hydrologist with the National Oceanographic and Atmospheric Administration.