Health and Human Services Secretary Robert F. Kennedy Jr. says he took a Mother's Day dip in Washington, D.C.'s Rock Creek Park with his grandchildren – despite long-standing warnings that high bacterial levels make the water unsafe.

Kennedy announced the Sunday outing in a social media post that included several pictures, including one in which he appears submerged in the creek, a tributary of the Potomac River.  

“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,” the post reads.

The National Park Service says, “swimming and wading are not allowed due to high bacteria levels,” according to The Hill newspaper. 

Swimming has been prohibited in most of D.C.’s waterways since the 1970s, largely because of contamination from the District’s aging sewer system, the newspaper also reports.

Health and Human Services has not responded to The Hill’s request for comment on Kennedy’s swim or concerns about the water’s contamination.