Pugneys Country Park in Wakefield have advised dog owners to take the "precautionary measure" as "small amounts" of algae had been found.
The lake at Pugneys is frequently hit by the issue.
The lake was closed off in 2019 due to high levels of bacteria.
High levels of bacteria were also found in the water during routine testing in 2018.
Green algae can cause rashes and irritation in humans, and can be toxic if ingested by animals, even in small quantities.
The group warned that symptoms of exposure can appear within a few minutes or hours, depending on the type of toxin ingested.
Symptoms include vomiting, diarrhoea, drooling, disorientation, trouble breathing, seizures and blood in faeces.
If left untreated, it can cause liver damage and ultimately be rapidly fatal.
Daniella Dos Santos, junior vice president of the association, said at the time: “We know that some dogs enjoy nothing better than a paddle in a cool lake while on a walk during summer months, but my advice to pet owners would be to keep your dog on a lead during walks near water confirmed to have toxic algal blooms.
"While not all blue green algae are poisonous, it is impossible to tell the difference visually, so it is better to be safe than sorry.
“There is currently no known antidote for the toxins, so prompt veterinary treatment is essential to tackle their effects and ensure a good chance of recovery.
"If you suspect your dog has been exposed to blue green algae, rush it to your local vet
A statement on the Pugneys Facebook page read: "We have small amounts of algae present in the water. As a precautionary measure its advised that dog owners do not allow their animals into the water.
"We do encourage visitors to keep their animals on leads for wildlife and other park users.
"We do now have a dog walking area where dogs can be unleashed."