After treating its water against the parasite Cryptosporidium, Burger's Lake has reopened for the first time since July 16, NBC5 reported.
Workers at the popular swimming hole completed the hyperchlorination process recommended by health officials, a park worker said. Hyperchlorination involves "shocking" the water with a concentrated dose of chlorine.
As of Wednesday, the department had confirmed 20 cases of cryptosporidiosis. Symptoms include diarrhea and nausea.
Crypto, which is resistant to normal chlorine levels, is the most common cause of waterborne illness in the United States.
The source of the outbreak was likely feces from an infected person.