Elliott B. Nelson, the assistant to the city manager, is leaving for a similar position in Champaign, Ill.
City Manager Sharon A. Addison said she has not decided how she will replace Mr. Nelson, who has worked in City Hall since January 2010.
His last day is Sept. 27.
During his three years at City Hall, Mr. Nelson, 27, worked under three different city managers, first under Mary M. Corriveau until she retired in April 2012, then with interim City Manager John C. Krol and finally with Ms. Addison for the past 15 months.
I learned the organization under three different city managers, he said, adding he is thankful for the experience.
To save money, the Watertown City Council left the position empty for 18 months after Bryan L. White left to become Canandaiguas assistant city manager.
Mr. Nelson was hired by Ms. Corriveau.
He will be leaving for a city with a population of 82,000 residents and 24,000 students at the University of Illinois. He also will be about three hours away from his father and brother.
And hell be closer to his beloved Chicago Cubs and Milwaukee Brewers, teams hes followed since growing up in Michigan.
I will be living in Illinois when the Cubs win the World Series, he said.
Mr. Nelson, who came from Central Michigans master of public administration program soon after graduating, will be a supervisor overseeing a staff in the city managers office, something he has not done in his position here.
His new annual salary will be $57,000.
Its a real big step for my career, he said. Its the next logical step for my career.
In his stint here, Mr. Nelson tried to figure out how to rid the city of its pesky crow population of 20,000 birds, helped with the transition when Ms. Addison was hired and oversaw putting together meeting agendas.
Ive learned more about crows than I ever thought I would, he said.
Mr. Nelson stressed he likes Watertown and will miss Northern New York.
Hes done a fabulous job, Ms. Addison said. Its a big loss for the city.