LIFTED: Lake Alert for Lake Arnold

Entered on: February 01, 2019

UPDATE: The water quality in Lake Arnold has returned to acceptable standards and the Lake Alert has been lifted. Please resume all normal lake activities.

February 8, 2019 - Lake Alert Remains in Effect for Lake Arnold

City Stormwater staff continue to detect microcystins (toxins) in Lake Arnold at potentially unsafe concentrations in isolated pockets where algae is present. The toxin levels in these areas may be potentially unsafe for humans and pets. Please continue to refrain from swimming, recreating, and irrigating from the lake until further notice.

City staff are monitoring and evaluating Lake Arnold on a weekly basis. This evaluation period will help determine the best course of action moving forward.


February 1, 2019 - Lake Alert Issued for Lake Arnold

On February 1, 2019, the City took water samples in Lake Arnold to determine the presence of microcystins (toxins) resulting from an algae bloom in the lake.  It was determined that potentially unsafe concentrations of toxins are present in Lake Arnold.  As a precaution, we are advising everyone to refrain from swimming, recreating and irrigating in/from Lake Arnold until further notice.

 For reference, cyanobacteria/blue-green algae are always present in the water. These blooms are caused by low-flowing, warm water and excessive nutrients that can come from a combination of fertilizers, septic tanks, yard waste and pet waste. Blue-green algae can pose a health concern based on its ability to produce toxins. Toxicity is hard to predict because a single species of algae can have toxic and non-toxic strains.  Even blooms caused by known toxin-producing species may not produce toxins or may produce toxins at undetectable levels.

Because of the potential for harm to humans and pets, the City will begin performing weekly microcystin testing until the algae appears to have died. Please encourage your neighbors to register for the Lake Alert at so they too will get important information about Lake Arnold directly.

In the meantime, as we stated above, the City would advise refraining from swimming, recreating and irrigating in/from the lake until further notice. Please be aware that as the algae dies, a “musty” or other unpleasant odor may occur.

For more information on blue-green algae blooms, visit the Florida Department of Health page

If you should have additional questions, please email us at