Beach monitoring means checking the water quality at swimming beaches to make sure it’s safe for people to swim in, helping reduce the risk of recreational water illnesses. Monitoring agencies test water samples for bacteria, such as E. coli, which tell us that germs that can cause illness might be in the water.

Remember: Water conditions can change quickly, so beach monitoring results don’t always reflect what the water is like right now. Because samples cannot be taken constantly, they only show what the water was like at the moment the water was sampled.

How often a beach is tested – and the criteria for posting advisories or closing beaches – can differ between programs. Check the monitoring program’s website to see how often they test the water and when they decide to issue an advisory or close a beach.