Here is an excerpt of the DES press release regarding the 2004 fall drawdown of the lakes.
Not included in this schedule is Lake Winnipesaukee. Unlike the other lakes in this schedule, Lake Winnipesaukee is not purposely drawn down in the fall. Instead, each year on Columbus Day, the releases from Lakeport Dam are reduced from a normal minimum of 250 cubic feet per second (cfs) to a flow between 30 and 50 cfs for a period of up to two weeks to allow for maintenance of the dams and hydropower facilities on the Winnipesaukee River. The flow of 30 to 50 cfs is the minimum flow needed to maintain the downstream aquatic life during this period.
By the middle of the fall, Lake Winnipesaukee is, on average, 15 inches below its springtime full level due to evaporation and releases from the lake that have occurred over the course of the summer. As a result of the reduction in the amount of water released from the dam after Columbus Day, the lake level does not drop for the remainder of the month of October and is generally maintained at this level through the month of December. Depending on the amount of snow on the ground in the winter, the lake level may be lowered further beginning in January to a depth of two feet below the normal full level.
DES Press Release