Public Health Madison & Dane County

Keeping up with ever changing beach conditions is a full-time job for our environmental health lab in the summer.

During the summer months, staff visit area beaches, conducting visual inspections and collecting water samples to test for E. coli bacteria and cyanobacteria (blue-green algae). If a blue-green bloom is present or test results show elevated bacteria levels, we close beaches and post signs to reduce the potential toxin exposure and to prevent people from becoming ill.

Once a beach is closed, weekday follow-up occurs until bacteria levels are acceptable. This summer, the 20 beaches we monitor have been closed for a total of 143 days since monitoring began on Memorial Day. This is more than double last year’s beach closure rates at this time.

Blue-green algae blooms, that can be toxic to people and pets, have been the main beach closing culprit this year. Nutrients like phosphorus and nitrogen contained in storm water run-off, combined with hot days with calm winds make the perfect environment for blue-green algae to grow to blooms. Thankfully, they can dissipate when weather changes.

On top of collecting and testing water samples, our lab staff are answering a lot of questions about lake water quality and current conditions. By our current count, we have appeared in 19 media stories with tips on how to stay healthy while swimming and keep our water safe.

If you would like to know more about current beach conditions or monitoring practices, visit our Beaches, Lakes, & Pools webpage, and remember, before swimming, always take an overall look at water conditions since conditions can change quickly, and testing results may not always reflect real-time water quality.