On November 21, the shore of Lodi Lake was abuzz with activity.

The fifth-graders in Mrs. Martina Ruiz’s class at Needham Elementary School were there to work alongside Barbara Transon of Lodi Unified School District, Watershed Program Coordinator Kathy Grant of the City of Lodi, and U.S. Fish and Wildlife biologists Donnie Ratcliff, Kes Benn and Erin Gleason.

The goal for the day: To process the leaf packs they had created and set out in Lodi Lake, the Mokelumne River, Cattail Creek and Pigs Lake in October, braving the pouring rain for science.

Back in October, the students placed the leaf packs at eight sites, then got a tour of the Lodi Lake Nature Area and Discovery Center.

Last week, it was time to find out if any macroinvertebrates had moved into the leaf pack homes the students created.

Processing the leaf packs had several steps. The students opened each pack, then rinsed the leaves to shake loose any macroinvertebrates — bugs that, in healthy bodies of water, make their homes in leaves and detritus collected among rocks and fallen tree branches. Or, as the students hoped, in man-made leaf packs.

Once the leaves were rinsed, the water they had used was poured through a strainer, and the students used small, soft pits of screen to scoop out crawly critters. Then they used keys at each table to identify all of the macroinvertebrates and sort them.

The students shouted with excitement as they found the bugs they’d been looking for.

“I love the crayfish! That one’s my favorite!” one student said. Another was thrilled that the little bugs were alive. As Ruiz encouraged a group of girls to pick up some stonefly larvae that the biologists had brought from the American River to show the class, they shrieked — then picked the bugs up anyway, and showed them off to the adults.

Transon, Grant and the Fish and Wildlife biologists were on hand to help as needed. Students also had the chance to use magnifying glasses and microscopes to see the smallest creatures.

The goal of the leaf pack project was to get some data on the health of Lodi Lake and the Mokelumne. A wider variety of bugs in the leaf packs signals that the water is a healthy ecosystem.

A couple of the leaf pack sites in Cattail Creek, which runs through the nature area, and Pigs Lake became the homes of a wide variety of macroinvertebrates. However, others showed a sparser population. A pack by the boathouse had a lot of the tiny creatures, but mostly just one type.

Still, the results don’t necessarily mean the lake or river are unhealthy or healthy. The cool, rainy weather may have had an effect on the packs, along with “pulses” of water flowing from upriver. And to get a better sense of the data, the leaf pack experiment should be conducted several times, not just once. More Lodi EEI classes are hoping for a chance to test the Lodi area’s water in the spring.

In the meantime, the kids got a firsthand look at how scientists test water from rivers and lakes — and to share their findings with the Leaf Pack Network as citizen scientists.