CONCORD — The New Hampshire Department of Environmental Services has announced the schedule for the annual fall drawdown of the lakes and ponds controlled by state-owned dams.
The earliest local lake on the schedule is Suncook Lakes in Barnstead, which will be drawn down five feet from full lake — not from the current level — on Sept. 30.
Due to changing ice and hydrologic conditions, the lake levels can vary throughout the winter. Since the hydrologic conditions and recreational uses of the water bodies vary, the degree and date of the start of drawdown for each lake also varies, and could be affected by the amount of rainfall during the period.
The actual date at which the drawdown will begin could vary by a few days, based on operational constraints.
Most of the other local drawdowns will occur on Oct. 14: Barnstead Parade will be drawn down 1.5 feet from full lake level; Crystal Lake in Gilmanton, down three feet; Newfound Lake in Bristol, two feet; Shellcamp Pond in Gilmanton, two feet; Squam Lake in Ashland, 2.5 feet; Sunset Lake in Alton, seven feet; and Webster Lake in Franklin, two feet.
Lake Kanasatka in Moultonborough will be drawn down 1.5 feet on Nov. 5.
Unlike other lakes, Lake Winnipesaukee is not purposely drawn down in the fall. Instead, after 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. This year the reduction will begin on October 14.
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 the same 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.
Lake drawdowns are conducted each fall to reduce winter ice damage to shoreline properties and to reduce spring flooding. Drawdowns also give property owners an opportunity to conduct any necessary repairs to their waterfront property, provided they first secure a permit from the state Wetlands Bureau at 603-271-2147.