NHS Tayside has issued a warning that potentially deadly bacteria could strike local waterways.
With Easter holidays still ongoing, the health board has released an alert that hazardous blue-green algae could appear in the city’s most popular sunspots.
The bacteria, which can kill dogs and cause “severe” symptoms in humans, emerged at popular beauty spot Clatto Reservoir last June.
Dr Jackie Hyland, consultant in public health medicine for NHS Tayside, said: “We routinely monitor levels of blue-green algae over the warmer months because of the potential health risk to people and to animals.
“Canoeists, wind surfers and swimmers who come into contact with the algal scum or who accidentally swallow affected water can suffer from complaints such as skin rashes, eye irritation, vomiting, diarrhoea, or pains in muscles and joints.
“These symptoms are usually mild, but in some cases, can be severe.
“The risk to small animals like dogs is significant over the summer months as they tend to drink more water in the heat and may eat shoreline algal crusts.
“Dog owners should keep an eye on their pets, especially if they come into contact with water which could be affected.
“The public should be reassured that public water supplies are always treated to prevent any harmful effects to health due to blue-green algae.”
Blue-green algae are tiny organisms which develop naturally in lochs, ponds, reservoirs, rivers and in the sea.
“They are a common seasonal occurrence and waters which have been affected by agricultural, domestic or industrial discharges are most at risk of developing the algae.
The algae can multiply during the summer and discolour the water which then appears green, blue-green or greenish brown and, occasionally, they clump together to form a scum on the surface of the water.
At the shoreline, algal crusts may appear brown to almost black.
The algae have been a recurring problem at Clatto Reservoir for several years. The site used to attract more than 95,000 visitors annually and had a thriving watersports scene, but now receives fewer than 35,000 people a year.
NHS Tayside confirmed that a number of sites across Courier Country are being monitored for the algal blooms.
Areas under scrutiny include Backwater, Clatto, Den of Ogil, Glenogil and Lintrathen.