The Sprayground at Seneca Lake State Park closed August 15, following the onset of illnesses.
Officials are still investigating how cryptosporidium was found in two storage tanks that supply water for the park near Geneva.
"We recognize this is a significant outbreak and our priority is to continue working with counties to increase public awareness about the precautions everyone should take to stop further spread of illness," says state Health Department spokesman Jeffrey Hammond.
Dr. Andrew Doniger, Monroe County's health director, says that more reported illnesses are coming from those who had contact with sick children.
Cryptosporidiosis is very infectious and can cause symptoms including diarrhea, nausea, vomiting and fever.
The Centers for Disease Control and Prevention says that a similar outbreak affecting nearly 5,500 people occurred in 1995. In another incident, more than 400,000 people became sickened in 1993 after consuming contaminated drinking water in the Milwaukee area.
