However, if significant rainfall occurs over a short period of time, flooding could result. This is a secondary factor and can add to rainfall events. Snow water equivalent is the amount of liquid water contained in the snow. Snowmelt alone should not produce major floods. Ice jams can cause increased damage by temporarily blocking rivers and streams and causing higher water levels behind the jam.
Peak flows downstream increase when jams break up and quickly release stored water.
Warm days with freezing night temperatures allow a gradual melting and runoff of the snowpack. A sudden warm up, especially when coupled with significant rainfall, can send large amounts of runoff into rivers and streams. Maine's headwater storage reservoirs typically reach their annual low water levels in March. These reservoirs can moderate downstream flood peaks if rainfall occurs above the storage dams while the reservoir's water levels are down. The reservoir systems have limited ability to moderate flood peaks in the lower parts of the river basins if large amounts of rain fall or if heavy rains fall downstream of the storage dams.