Cayuga Lake is back to normal after beginning the season with low water levels. The New York State Canal Corporation, which is responsible for lake levels, was prepared for a heavy runoff as the large snowpack melted, according to Bill Kappel, a hydro-geologist at the United States Geological Survey. That didn’t happen. Instead, Kappel pointed out that temperatures stayed low, melting the snow slowly and even allowing it to trap some of the rain that fell on top of it.
With most of the snow finally gone, the next goal is to raise the lake level for summer. The Canal Corporation reported that the water control gates at Mudlock at the north of Cayuga Lake were closed on Mar. 27, leading to an increase of 2.3 feet by last Wednesday. At that time the Canal Corporation planned to let lake levels rise another 1.2 feet in order to reach normal navigation level. They foresee no problems that might interfere with the opening of the navigation season on May 1.
“People think this is a bathtub,” said Kappel. “You just pull the plug and the water level goes down. But it doesn’t happen that way.” As the lowest of the Finger Lakes, Cayuga takes water from the Keuka and Seneca Lake watersheds as well as its own. “It’s a very fast-reacting system to fill and a very slow-reacting system to drain,” said Kappel.
An inch of rain across the Cayuga Lake watershed can potentially raise lake levels by a foot within a couple days, but each day only a tenth of a foot can drain through the Mudlock control structure at the lake’s north end, according to a USGS fact sheet. Remember the rise of 2.3 feet over 12 days? The lake level could have only been lowered by about 1.2 feet in those 12 days. Since lake levels can change much more quickly than managers can react, the Canal Corporation must anticipate water events.
Unfortunately weather forecasts are only accurate out to a few days. So the Canal Corporation uses rule curves, target levels that change throughout the year. Flooding is an obvious danger of high lake levels, but low lake levels could impact navigation and water supplies. The target levels get very low in the spring when there is a large snowpack because there is no way to predict how the snow might melt.
To add to the complexity, there are times that the water on the other side of the Mudlock control structure is higher than the water in Cayuga Lake. Opening the water control gates would then lead to lake levels rising rather than falling, which could have happened during the major flooding event in 1996 when rain and snow raised the lake level four feet in just a few days.
Input from other lakes is another wild card. The Canal Corporation said that Seneca Lake, operated by the Seneca Falls Power Corporation, has recently started discharging significant amounts of water into Cayuga, which the Canal Corporation will have to account for in their management plans. “The barge canal folks need a crystal ball,” said Kappel.
Nancy Ahlers and her husband moved onto the lake in the 1970s. She remembers approaching the carport one night and seeing water reflect back their headlights. They had ducks swimming in their carport and eight inches of water in their boathouse. They have had less problems with low water, which mostly affects their deep-keeled sailboat. Her husband would frequently call the women who was then in charge of lake levels so that he could move their sailboat before the water got too low for the winter.
Some of the speed with which Cayuga Lake can fill is our own doing. Kappel said that he found barge canal reports from 150 years ago that acknowledged water was reaching the lake faster because of the way people were changing the land. Destroying wetlands and improving drainage for farming or other land uses meant less water was retained by the land when rain fell and snow melted.
There are options for property owners looking to slow down the runoff from their land. The Stormwater Coalition of Tompkins County educates the public as well as municipalities about water runoff. Angel Hinickle, the program coordinator, said that even programs on erosion and sediment control usually contain a segment on how to increase infiltration and retention of water. She recently spoke at the Tompkins County Cooperative Extension about rain gardens and rain barrels. Other techniques include permeable pavements and bioswales.
“Anything that folks can do to reduce the amount of water that quickly gets into stormwater pipes is good,” said Kappel, but “eventually all water flows downhill.” The Canal Corporation is currently working on an 8.5 million dollar project to build a Canal Flood Warning and Optimization System that will encompass three river basins, including the Oswego basin in which Cayuga Lake is located. They estimate the web-based system will be operational this year, providing water level information and flood warnings.