Julie Geiser, director of the nursing service, would not release the identity, age or gender of the victim, or the date of the death, citing medical privacy laws.
Deputy Coroner Kevin Rogers said his office had no report of any salmonella-related deaths.
Geiser said it was not known how the deceased contracted salmonella.
But the strain of salmonella found in the victim was the same as that found in the city's water supply, according to tests by the Colorado Department of Public Health and Environment.
During the outbreak, the use of tap water for drinking was banned for 24 days, until the state confirmed April 11 that the city's water system had tested clean for salmonella and other bacteria.
Since health officials received news of the first illness March 6, there have been 411 reported salmonella cases and 112 confirmed through laboratory testing. The outbreak also has led to 18 hospitalizations, although Geiser did not know how many victims remain in the hospital.
Dr. Bill Briton, the epidemiologist for the San Luis Valley region, said the number of daily reported salmonella cases dropped dramatically following the city's chlorine treatment of the water system, although health officials continued to receive up to three reports per day of people with symptoms that could be related to salmonella.
Health officials reiterated the need for proper hygiene to prevent the spread of the illness through person-to-person contact.
Those practices include thorough hand-washing, especially after using the bathroom or changing diapers. Cutting boards and utensils also should be disinfected before use with a second food item.
The county nursing service advised anyone with symptoms, which include loose stools, should not prepare food for others. Restaurant and health-care workers should not return to work until at least 24 hours after symptoms have stopped. Babies and young children should not be taken to child-care centers or attend school until at least 24 hours after diarrhea ceases.