By Deb Patterson
SYRACUSE — Results after 2½ years of the Wawasee Inlets Nutrient Study have provided eye-opening information for the Wawasee Area Conservancy Foundation.
“For the first time we have street scientific defensible lines in the sand that you can use to tell if you’re making progress,” said Dr. Jerry Sweeten, president of Ecosystems Connections Institute, who is spearheading the study.
Sweeten’s presentation was part of the WACF’s annual Lake Celebration Saturday, July 31. The event was held at the WACF Ruddell Pavilion on the WACF Educational Center property.
Sweeten’s presentation provided some information that was not known about Wawasee before the WINS study began. There is now two years of data available and the study is halfway through the third year.
Sweeten spoke of why nutrients and sediments matter, the measuring and accuracy of the amount of nutrients and sediments entering and leaving the lake. “If you have too much entering, then you have to deal with the consequences and how the lake responds. The response may not be what you like …,” Sweeten stated.
From the automatic water samplers located on the lake and the analysis of the samples, started in 2019, a report for 2020 has been finished. “Every year is different,” he stated.
He noted in 2020 one of the largest rain events was recorded with 4 inches of rainfall in May. Photographs of large sediment plums entering the lake were shown and captured by the automatic samplers. From the data collected it was learned 2019 had 40.5 inches of rain, but in 2020, in spite of the big rain event, there was 30.7 inches. “That has a huge effect on nutrient process entering and leaving,” he said.
Hydraulic retention information was provided. He noted in 2019, 43% of the water was replaced in Lake Wawasee and it would take 2.2 years to replace all the water in the lake. “In 2020 that number was cut in half. The flushing rate was about 28 percent. The retention time is 3.5 years for all water to be replaced … suggesting is this is a moving target, every year is different … beauty of the study is it gives us a glimpse of the dynamic nature of the lake through numbers like this.”
Sweeten announced Turkey Creek and Dillon Creek accounted for 68 percent of the phosphorous entering the lake in 2020. But Martin Creek contributed the most phosphorous per pound even though it has the smallest watershed. “The pounds per acre from Martin Creek turned out to be the highest amount.”
Sweeten added the phosphorous reduction increase in 2020 was 135% from 2019. He explained 2020, despite the one major rain event in May was a dry year and a lot of stuff didn’t get flushed through the system. Further explaining he said phosphorous reduction needs to take place to bring the lake back.
He also noted the sediment increased 60% in 2020 from 2019. He equaled that to 103 Chevy Suburbans full of sediments or 25 tri-axle dump truck loads entering the lake. “We know from the data what sub-water should be the focus of the attention to begin the process to reduce that amount. For the first time, we have street scientific defensible lines in the sand that you can use to tell if you’re making progress. We know for sure when going to funding agencies or have conversations with stakeholders… scientific defensible (data) with this project.”
Sweeten also talked about what is next for WACF which would be turning “off the nutrient and sediment tap … you’ve got to be in it for the long haul.” He mentioned the strategic things which could be done, one of which WACF has begun – a directive of where to help with “turning the tap off.” He noted the data will provide leverage toward grants, building relationships. He noted the importance of periodic assessments to indicate if things are better, worse or the same.
“The data use for that purpose will tell you one thing for the future generations of the lake and the health of the lake.”