A Greater Shepparton City Council spokesperson said the staff member worked at Aquamoves on Tuesday, August 4 and the morning of Wednesday, August 5.
"The affected staff member is now in self-isolation as are other Aquamoves staff that may have been in contact with their colleague," the spokesperson said.
"Council has closed Aquamoves today to all staff with a deep clean of the facility to be undertaken."
Aquamoves has been closed to patrons since Thursday, August 6 when stage three COVID-19 restrictions were enforced.
The spokesperson said the staff member contracted the virus outside of Aquamoves, and "acted immediately and responsibly", and had "minimal" close contact with Aquamoves patrons.
"In performing their role, the staff member has had minimal close contact with patrons attending Aquamoves on August 4 and 5," the spokesperson said.
"A “close contact” is defined as being anyone who has been in close proximity with an affected person for 15 minutes in the same room for two hours.
"Contact tracing is now being undertaken by GV Health who will make direct contact with anyone they believe may be at risk of contracting the virus as a result of attending Aquamoves at the identified time.
"Council takes the health, safety and wellbeing of its staff and community extremely seriously and is following the Chief Medical Officer’s direction in dealing with a positive on-site case."
Greater Shepparton reported 12 active cases of COVID-19 on Tuesday, and an update on the number of active cases is expected later today.
Victoria recorded 410 new cases, and 21 deaths today.