Health and Human Services Secretary Robert F. Kennedy Jr. shared photos of himself submerged in Washington, D.C.'s Rock Creek with his grandchildren, despite longstanding warnings that high bacterial levels make the Potomac River tributary unsafe.

       "Mother's Day hike in Dumbarton Oaks Park with Amaryllis, Bobby, Kick, and Jackson, and a swim with my grandchildren, Bobcat and Cassius in Rock Creek," RFK Jr. wrote alongside four photos from the outing posted to X on Sunday.

       The photos show the 71-year-old member of President Donald Trump's administration both sitting in the water and completely submerging in the shallow creek.

       Mothera？？s Day hike in Dumbarton Oaks Park with Amaryllis, Bobby, Kick, and Jackson, and a swim with my grandchildren, Bobcat and Cassius in Rock Creek. pic.twitter.com/TXowaSMTFY

       — Robert F. Kennedy Jr (@RobertKennedyJr) May 11, 2025

       Longstanding warnings from the National Park Service (NPS), however, say to stay out of the water because of high bacteria levels.

       "Rock Creek has high levels of bacteria and other infectious pathogens that make swimming, wading, and other contact with the water a hazard to human (and pet) health," the federal agency warns on a webpage for the park.

       Staying out of the water also helps to protect the natural landscape from erosion and negative impacts to wildlife as well, according to the NPS.

       Washington, D.C., has banned swimming in waterways for over 50 years because of the widespread contamination.

       According to the Environmental Protection Agency, Rock Creek has been found to have "fecal contamination" from sewage and high levels of bacteria, including E. coli.

       Despite the federal warnings and signs in the area detailing the risks, people have been known to still swim or wade in the water.

       ABC News has reached out to Robert F. Kennedy Jr. for a comment.