It was only a trickle.

But for Kaylie Judge and her mother, who roamed the grounds of the Carpenter St. Croix Valley Nature Center last Sunday to see how maple syrup is made, the clear liquid dripping from a tree into a large metal bucket was confirmation that they had hit the sap jackpot.

"It tastes like, kind of sour," the 9-year-old from Hastings said after she placed her fingers beneath the spout to catch a drop and put it to her lips.

Kaylie and her mother, Tammy Judge, were among the 50 or so kids and adults who participated in a two-hour program organized by the nature center to show newcomers and experts how to tap maple trees for the "sour" and watery substance also known as sap.

Every March, several naturalists at the center demonstrate the arduous process of gathering sap and boiling it down to make the sweet delicacy poured over pancakes and waffles.

"It's kind of a ritual of spring, when the snow starts melting and it starts warming up you want to go out there and see if those trees are running," said program director Mayme Johnson, who's been leading the class for more than 28 years.

The center is tucked away in south Washington County, north of Hastings, on more than 700 acres of land. Its naturalists have been tapping the same trees for more than 30 years, Johnson said.

Sunday's program started with a crash course in sap gathering, which Johnson said American Indians started hundreds of years ago, before European settlers arrived in North America.

After about a half-hour, kids and their parents, armed with hand drills and metal buckets, split into groups and headed outdoors to lodge spouts into trees to see if the treasured resource was flowing.

Each group tapped two trees, collected sap from where it was available, and then ended up at an evaporator, also known as the "sugar bush," where everybody was given a sample of maple syrup collected last year.

For many, the outing is a family tradition. Some adults learned to collect sap when they were children, and now bring their own kids.

"I was here when my daughter was a kid many years ago with my mom and dad," said Peggy Katz, of Hastings. "My dad learned how to do it from [the program]."

Hudson native Cara Beausoleil brought her 10-year-old son, Jaece Calkins, to the program, which she said is similar to a class she attended as a child.

"I went when I was in kindergarten," Beausoleil said.

The class offers only a glimpse of the syrup-making process. It takes 86 gallons of sap to make 1 gallon of syrup, Johnson said. Then comes the boiling process, which she said can take several hours to days.

"I don't think some people appreciate it … you have to kind of like it," Katz said, adding that once her father learned how to make syrup, he was hooked. "He used to get bag after bag. He must've got like 2 gallons [of syrup]."

While above-average temperatures in recent weeks have made it easier for folks to get in and out of the woods, Johnson said the warm spell could make it more difficult to gather much of the sticky substance.

"I would expect it to be a much shorter season, which means we're not going to get much sap," she said.

Jerry Jacobson, vice president of the Minnesota Maple Syrup Producers Association, an organization of more than 120 hobbyists and producers of maple syrup in the state, said members are already reporting that the 2015 sap-tapping season has been less than prosperous.

"Last week was not good. It got warm last week … nobody's had any really good runs after that," he said, adding that he hopes lower temperatures in coming days will trigger a sap flow. "The next two weeks will be kind of critical. I think it's going to be an early spring."

Nevertheless, Johnson said she believes some people are tapping their own trees at home, based on the number of spiles, or spouts, the center has sold.

"There's a fair amount [of people] who go out and do their own," she said. "It's fun to hear when people call back and say they've got their finished product."

Blair Emerson is a University of Minnesota student reporter on assignment for the Star Tribune