In tests taken Wednesday, the average level of bacteria for Rehoboth Beach over the past 30 days was about 27 colonies per 100ml. That level was 1,313 per 100ml. In Bethany, the bacteria level was much higher at 3,873 colonies per 100ml. Bacteria was far less elevated in Dewey, with 160 per 100ml.

Yes, bacteria are naturally present in the waters of Rehoboth Beach, Delaware, and are monitored strictly by the DNREC Recreational Water Program. The primary indicator tested is Enterococcus, a bacterium found in the intestines of humans and warm-blooded animals. While the ocean water at guarded beaches is usually safe for swimming, high levels can occur, particularly after heavy rainfall which washes wildlife waste and urban runoff into the sea. In such cases, DNREC issues swimming advisories to alert the public of potential risks like gastroenteritis. As of 2026, Rehoboth Beach remains a popular, guarded destination where water quality is tested regularly from May through September. Visitors should look for the color-coded flags at the Beach Patrol headquarters: a high bacteria count or dangerous surf may result in a caution flag. Those with compromised immune systems are advised to avoid submerging their heads, especially in the nearby "Inland Bays" where water circulation is slower than on the Atlantic coast.