Shown is the Lake water budget for Wawasee and Syracuse Lakes combined for 2012 drought year, including inflows and outflows, irrigation outflow refers to residential irrigation systems pulling water directly from the lake. Net groundwater flows vary from net inflow (positive value) to net outflow (negative value). All values in millions of cubic meters.
A research study on Wawasee and Syracuse lake levels during the drought of 2012 has been completed and Kosciusko Lakes and Streams has released its findings.
In short, “Lake levels were likely affected by residential irrigation in 2012, though groundwater inputs to the lake likely compensated for some of the losses.”
Dr. Nate Bosch, director of Kosciusko Lakes and Streams, Grace College, released the report last week. The study was done by Bosch, Margaret Lee, Amy Bloemendaal and Anna Burke.
“Many Lake Wawasee and Syracuse lake residents contacted us with questions and concerns after the drought we experienced in 2012 and the low lake levels. We produced a figure showing the historical record for lake levels as well as a fact sheet about lake levels to give context to the 18-inch lake level drop … it became clear we needed to conduct a research study on the lake levels and we were encouraged to have several Wawasee and Syracuse lake residents make donations to make the research possible,” said Bosch.
The conclusion to the study notes main causes of changing lake levels are uncontrollable and cannot be controlled by lake managers and property owners, nor can these individuals control how much water leaves the lakes and enters the atmosphere through evaporation. But lake levels can be controlled, such as dam operations when water can go over the spillway.
“Lake property owners have control over water lost from the lake due to residential irrigation systems. For future drought events, it may be effective to limit irrigation systems during times of lower lake levels.
“The expansion of agricultural irrigation systems,” according to Bosch, “is something to continue to monitor. If these irrigation systems widely increase, they may start to have a measurable influence on lake levels during drought conditions as well.”
Water budgets for the lakes and watershed were developed. Results show the total inflow into the lakes decreased by 28 percent from 2011 to 2012, while outflow decreased by only 19 percent over the same time. Precipitation was the largest inflow, 42 percent, in 2011 and groundwater was the largest, 51 percent, in 2012. For outflows, Syracuse dam was the largest, 54 percent in 2011 and evaporation was the largest, 54 percent in 2012.
Residential irrigation outflow directly from the lakes was about 11 percent of the total outflow in 2011 and increased to 22 percent of the total outflow in 2012.
Industrial and agricultural irrigation in the watershed was only 1 percent of the outflow in 2011.
“Implications for this study include management consideration of human-controlled lake level influences of the dam outlet and irrigation usage, especially during drought years. However, while humans can control these outflows, inflows of precipitation and stream inputs are uncontrollable such that lake levels can never be fully managed.”
Study Discussion
Inflows to the lakes were higher in 2011. The 2012 rainfall amount was half the annual precipitation of 2011. With little snow in winter, or rain in the spring, the lake was not able to replenish water lost through evaporation, irrigation and dam outflows. The lack of rain in 2012 also affected stream inlets. The streams delivered less than half the water in 2012 than in 2011.
The study did find lake outflows increased 23 percent in 2012 compared to 2011. “The lakes had less water entering and more leaving, that led to low lake levels.” Evaporation and irrigation took more water out of the lake in 2012 than in 2011. The evaporation increased because of warmer temperatures including the lake not freezing in the winter of 2012.
The full Wawasee and Syracuse Lakes Water Budget Report can be see at water.grace.edu under news.