COVID-19 levels in Palm Beach County have receded to their pre-July lows, but a strain of the flu and a nauseating stomach illness are spreading, the latest sewage tests show.

Recent wastewater samples from the Jupiter-area Loxahatchee River District show the lowest coronavirus concentration since summer started. But sewage testing also reveals the spread of the flu and norovirus infections.

“It appears the increase in COVID trends that began in July have dropped back down,” district Information Services Director Bud Howard said Tuesday by email. “However, the concentrations indicate that there is certainly still COVID circulating in the community.” Viral particle counts are more than twice as high as spring 2021, Biobot data shows.

Wastewater samples from the Jupiter-area Loxahatchee River District had about 313 coronavirus particles per milliliter, testing from Sept. 18 shows. It’s the lowest level since June 28, around the time the latest surge started, save for a one-time dip July 5. Boston-based private laboratory Biobot Analytics conducted those tests.