Keuka Lake Water Level ABCs-Peter Landre, Cornell Cooperative Extension
The water level in Keuka Lake is often a topic of conversation and debate around the lake. I often hear from lakeshore owners the "lake is too high!" or the "lake is too low!", sometimes in the same day! Why do people have different perceptions of where the lake should be? Hard to say, but many people seem to reflect on previous years or at what level they set their dock that spring.
To determine whether the lake is in fact too high or too low, people need to compare the current day's lake level with the "Keuka Lake Level Guide" or guide curve. The guide curve (published weekly in the local papers and on the KLA’s website) is the official guide used by the Keuka Lake Outlet Compact (KLOC) to manage lake levels. The guide curve illustrates the maximum and minimum desirable lake levels for the entire year. Ideally, the lake level on any given day should fall between the maximum and minimum. During the summer, the maximum desirable level is 714.2 and the minimum is 713.7 feet above sea level. On July 8 for example, the water level was 714.0; an acceptable level between the minimum and maximum. Currently the Keuka Lake Association and the KLOC are looking at installing a voice mail system so that people can call anytime to get the current lake level, desired levels and the gate settings for that day.
Who manages the lake level and how do they do it? The KLOC, a committee consisting of representatives from the eight municipalities around the lake, has ultimate responsibility for management of water levels and upkeep of the outlet gates. The recommended process for daily operation and management of the gates is outlined in the "Reservoir Regulation Manual-Keuka Lake Outlet", which describes the purpose and the procedures for maintaining the lake level. The Chair of the KLOC and the Director of Penn Yan Muncipal Utility Board (contracted to operate the outlet gates) consult on a regular basis to determine if the gate settings need to be changed to increase or decrease the outflow or discharge of water from the lake.
The primary objective of the KLOC is to use the six outlet gates to prevent flooding around the perimeter of Keuka Lake. The manual prescribes specific gate settings (and water discharge amounts), depending on where the level is in relation to the desired levels for that day. For example, if the lake were above the maximum desired level, the manual prescribes opening all of the gates to lower the lake until it reaches the desired level.
To minimize the risk of downstream flooding, the manual limits the discharge rate to 1,000 cubic feet per second (cfs). However, since this rate is not achieved until the lake reaches 716.03 feet above sea level or higher with all 6 gates open, gate capacity may be fully used to correct high water situations without significantly jeopardizing downstream property. The manual also prescribes that a minimum of 15 cfs is needed to safely operate the Penn Yan sewage treatment plant.
The six control gates are located at the Main Street bridge in Penn Yan. The three "main" gates were installed in 1993 and are made of steel with openings of 6'x7' each. There are also two "Andrews" Gates (4.5'x4.5') and one Birkett Gate (5.4'x4.0'). The "main" Gates are the primary control gates during higher water events. However, the Andrews Gates are used during high and low flow periods. At the current time, the Birkett Gate, because of its age and condition, is not normally used, except during extreme events.
Why isn't the lake level always kept within the desired levels? The water level obviously is highly dependent on the weather. During very wet or very dry periods, nature has more control and influence on the lake level than can be controlled by gate settings. If there is an extreme event, such as the 1996 or the 1972 flood, the gates simply cannot let enough water out of the lake to keep up with inflows. The KLOC is continually striving to improve and fine-tune gate settings during moderate rainfall events to minimize the "bumps" in the water levels. Close adherence to gate settings prescribed in the Operation Manual is critical to the success of keeping the level within the desired levels.
To help improve the effectiveness of lake level management, the KLA and the KLOC are currently investigating the possibility of installing two full service weather stations with lake level recorders on the lake (connected to a larger regional network) for more accurate weather assessment and forecasting. This system would allow more advanced warnings and "real-time" data for decision-making. The data would also be available to the public via the KLA’s website.