Images of a jampacked pool party at Lake of the Ozarks in Missouri over the Memorial Day weekend prompted St. Louis County to issue a travel advisory and the Kansas City health director to call for self-quarantine of the revelers.
The advisory by the St. Louis County Public Health Department cited news reports of large crowds at Lake of the Ozarks, where hundreds of people were recorded squeezed closely together amid the coronavirus epidemic.
"This reckless behavior endangers countless people and risks setting us back substantially from the progress we have made in slowing the spread of COVID-19," Dr. Sam Page, the county executive, said in a statement.
The health department expressed concern in its travel advisory that people from the St. Louis area were at Lake of the Ozarks over the weekend. "Any person who has travelled and engaged in this behavior should self-quarantine for 14 days or until they receive a negative test result for COVID-19," the advisory said.
It also says that employers are already being asked to screen workers for health risks and that they should also ask workers about their recent travel. The Lake of the Ozarks region is about 150 miles west of downtown St. Louis.
Dr. Rex Archer, director of the Kansas City, Missouri, Health Department, also tweeted his dismay.
"Anyone who didn't practice CDC, DHSS, and KCMO Health Department social distancing guidance should self quarantine for 14 days if they have any compassion for others," Archer wrote alongside a video of partying at Lake of the Ozarks.
DHSS is the state Department of Health and Senior Services, whose director, Dr. Randall Williams, said in a Memorial Day warning that the coronavirus that causes COVID-19 can be spread by those who show no symptoms but that when others get it, the virus can have tragic consequences.
The owner of the bar where the pool party occurred had told NBC affiliate KSHB of Kansas City that it would try not to let large groups gather and would try to enforce social distancing, but "we don't know who's in groups, who's in families. We expect them to do that on their own."
Jodi Akins, who attended the bash Saturday, told the station that guests' temperatures were checked and that sanitizer was on hand.
"If you're worried about getting sick, obviously, or you want to distance yourself, it's pretty much to each their own," Akins said.
Akins was identified as being from Blue Springs, Missouri, near Kansas City.
Camden County Sheriff Tony Helms said in a statement Monday that it was a "record weekend" at Lake of the Ozarks but that a lack of social distancing is not a crime and that his department had no authority to enforce it. Public health violations are up to health authorities, he said.
"We expect residents and visitors alike to exhibit personal responsibility at the lake," Helms said in a statement.
I know many people safely enjoyed the Lake this weekend while taking the appropriate safety precautions. But too many did not. And given potential for asymptomatic spread, this behavior creates much more risk for the rest of us. Contact @CityofSTLDOH if you feel you were exposed.
â€” Mayor Lyda Krewson (@LydaKrewson) May 26, 2020
The coronavirus can be spread in crowds, and health experts have stressed that people should keep their distance from others to slow its spread.
As of Monday, there had been more than 12,100 confirmed cases of COVID-19 in Missouri, with 685 deaths attributed to the disease, according to the state health department's website.
Kansas City, Missouri, had 962 confirmed cases and 22 deaths due to COVID-19, according to the city's website.
Download the NBC News app for full coverage and alerts about the coronavirus outbreak
St. Louis County and the city of the same name are at the top of lists when it comes to total cases and deaths in the state. There have been 4,455 cases of COVID-19 with 386 deaths in St. Louis County, and 1,739 cases with 107 deaths in the city.
St. Louis Mayor Lyda Krewson tweeted that many people enjoyed the Memorial Day weekend responsibly, but "too many did not," and she noted that the virus can be spread by those who do not show any symptoms. She asked that anyone who did not socially distance or wear masks to stay home for 14 days.