Longtime Stoughton Mayor Helen Johnson — who shepherded the city through the aftermath of a 2005 tornado and firmly supported bringing a controversial Wal-Mart Supercenter to town — will resign her post next week.

Johnson, 72, whom a colleague described as a "tiger" when it came to running the city, said Tuesday she's leaving to spend more time with family members who are ill.

"I certainly enjoyed working for the city," said Johnson, whose term ends in April 2010.

The Stoughton City Council decided Tuesday to call a special council meeting likely to be held next week to discuss the three options for how to fill Johnson's role until the end of her term. City Clerk Luann Alme said the council could decide then to allow the council president to assume the position, to appoint someone to the role for the remainder of the term or to call a special election to fill the position through April 2010.

Considered by many as feisty and no-nonsense, Johnson ran council meetings efficiently.

"It's a real blow … to the city to lose her," said Paul Lawrence, who has served on the City Council for 10 years.

"She comes across as very mellow and very sweet and she is … but when the chips are down you don't want to count her out," he said.

She was first elected mayor in 1990 after a landslide victory over Myron Wilcox in which she received 86 percent of the vote. She served until 1998, when she was elected to the Dane County Board for two terms. She returned to the mayor position after running unopposed in 2002 and is currently in her second consecutive term.

Among the highlights of her tenure, Johnson cites adding to the city's library; purchasing buildings for the senior center, utilities and emergency medical services; and establishing youth activities.

"The Wal-Mart, that was probably the biggest challenge," she said of the topic that divided the council for years.

Johnson also remembered the week of the Stoughton tornado, which happened the day after the city's Christ Lutheran Church and Martin Luther Christian School were destroyed by fire, as a particularly tough time for the city.