LONDON, ONT. -- Residents living in the area of three Southwood Lakes ponds are being warned of the possible presence of blue-green algae in the water Saturday.

The algae are microscopic bacteria that occur naturally in fresh water lakes, ponds, rivers and streams in the late summer and early fall.

In warm weather, with the right nutrients (phosphorous and nitrogen) and low wind, they can form a large mass called a bloom, City of Windsor officials say.

These blooms can make the water appear bluish-green, can form solid looking clumps, and may contain toxins that can be dangerous to the health of humans and especially animals.

The ponds in Southwood Lakes were designed as storm water facilities and not as recreational ponds, officials say.

Due to the suspected blue-green algae in the ponds, it is strongly recommended that residents refrain from using the ponds for recreational purposes. Pets and young children are particularly vulnerable to the effects of blue-green algae and should not be permitted to play in or near the water.

Residents in the area are also asked to restrict the use of fertilizers as they contribute to the growth of all types of algae including blue-green algae, the city says

For more information on blue-green algae, visit the Windsor-Essex County Health Unit website.