Fifty years ago this month, the city of Stillwater was one waterlogged battleground.

During Holy Week of 1965, the town saw its worst flood in history. Hundreds of teenagers joined adults and state prison inmates on the city's riverfront to fight the rising St. Croix River. Worried that the floodwaters would wash away their town, residents sandbagged tirelessly around the clock to build an 8-foot-high and nearly mile-long dike for protection.

Flooding was so bad that year that on the nearby Mississippi River and its tributaries, floodwaters swamped hundreds of houses and businesses and overran major highways and bridges, eventually driving about 19,000 Minnesotans from their homes. Members of the Red Cross and the National Guard were called in to help. President Lyndon B. Johnson declared 45 of Minnesota's 87 counties disaster areas.

Sue Ames-Lillie, 67, of Luck, Wis., was 17 and a junior at Stillwater High School when the St. Croix swelled and overran its banks. She and her classmates, along with students from other cities, went downtown to help build the temporary dike — marked with a sign that read "teenager's dike" — that saved downtown from being overrun.

"I just started kneeling in the sand and filling sandbags," Ames-Lillie said recently, adding that she started sandbagging in the afternoon and kept at it until the wee hours of the morning.

"When the Red Cross showed up I said, 'Ham sandwiches and coffee never tasted so good in my life!' " she recalled, chuckling at the memory.

Fifteen-year-old Doug Webster, right, was one of hundreds of teenagers who carried sandbags down the levee, decorated with Easter lilies. They staked their claim to that portion of Stillwater’s defense against the river.

The image of the "teenager's dike" sign would later be placed on a bronze medallion to honor the students who worked on it.

State officials also honored the teenagers with an engraved award in 1965, which was put on display in the governor's office.

Ames-Lillie, who still has her medallion, was so moved by her experience with the Red Cross during the flood that she later joined the organization as a volunteer.

"I want to be on the giving end of it … I want to go in and help, especially as I get older," she said.

The river crested at a record 694.07 feet above sea level on Easter Sunday 1965. Had the dike not been built, all of the buildings on Main Street would have flooded, said Roger Peterson, a City Councilman at the time.

Peterson, now 78, was in his first year in office when the flood hit. He said city officials didn't anticipate the river rising so fast, and the situation quickly turned into a "crisis."

In the days leading up to the flooding, city officials met with downtown merchants to make plans to build the dike.

Peterson was on duty at Stillwater City Hall when the flood crested. He and other council members traded 12-hour shifts at City Hall, while the mayor and the city administrator worked on the dike.

"Everyone worked well to get it done, the retailers, the buildings owners, the kids, even the convicts did what they had to do and we got the dike built and it held," Peterson said.

The flood caused hundreds of thousands of dollars in damage in Stillwater. In the years since, a permanent dike was built and new city codes were enacted requiring buildings to be built above the record crest level, Peterson said.

"What [the city has] done over the period of time hopefully will correct the situation," he said.

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