Columbia's Stephens Lake Park opened its gates for public swimming last week, but bacteria testing of that water doesn't begin until later this month.
The Columbia/Boone County Health Department said it waits until the temperature stays consistently warm to start weekly tests. This usually occurs around Memorial Day.
That way, there is an accurate picture of what the water quality is at that time.
ABC 17 News was unable to contact the Parks and Recreation Department as to why it opens before testing. The Health Department said there isn't an immediate health threat this early into the summer.
"It's so much of a roller coaster still in the beginning of May than it is the last week of May, Memorial Day time. It's usually hot and going to stay hot for the next few months," said Andrea Waner of the Boone Co. Health Dept.
The Department simply collects a bottle of water from a location and tests it at its in-house lab.
The level of E. Coli is monitored, which the Missouri Department of Natural Resources said is an indicator of the overall level of bacteria in the water.
"We can test it three times, and if it's high and over that EPA level three times in a row, that's when we'll post that public notification and contact the responsible parties if appropriate."
The Health Department does not, however, have the power to close a beach off. The health Department contacts the proprietor of the body of water, such as Parks and Rec or a specific Neighborhood Association.
The tests are educational and are done as a public service, according to Waner.
"We want to empower people to learn more about their environment, where they're going to swim and spend their time, that way they can make the appropriate decision for themselves and their families."
The Department doesn't voluntarily test every body of water in the city.
Waner said if people want to have a lake or pond near them tested to see if it's safe to swim in, they can contact the department to test it.