One hundred ninety Yellowstone National Park employees and concessions employees all tested negative in the latest round of COVID-19 testing. The tests were conducted on June 17 & 18.

Initially, one concession employee tested positive and was immediately isolated. The employee was retested twice more, and both tests came back negative. The initial test was listed as a "false positive" and the employee was allowed to return to work. According to the county health officer, a small percentage of "false positives" are normal in widespread surveillance testing.

That makes 577 Yellowstone-employee tests given since late May and all have been negative, which the exception of 162 tests conducted the week of June 22, which are pending.
This surveillance testing will continue throughout the summer as part of the park's reopening plan. The tests target employees who are first responders and/or work directly with the public.
Additionally, the park sampled wastewater systems in Gardiner, Mammoth Hot Springs, and Old Faithful between June 13 and 16. Lab results indicated 0% prevalence of COVID-19 in those systems at the time they were sampled. Additional samples were taken at Mammoth Hot Springs and Old Faithful between June 27 and 29, but those results have not come in yet.