The New Year's Day storm of 1997 was the most severe in recent history, with a total inflow of 1 million acre feet (equal to the entire capacity of Folsom Lake) over a 5-day period. However, this time the Bureau of Reclamation was able to limit releases to less than . The 1997 storm was a classic example of a "rain on snow" event, during which a warm tropical storm melted existing snowpack at lower and middle elevations, effectively doubling the volume of runoff. Prior to the New Year's storm, the winter of December 1996 had also been one of the wettest ever recorded, saturating the ground and depositing a considerable amount of snow.