After closing Lake Ballinger Tuesday, the City of Edmonds on Wednesday urged lake visitors to use “extreme caution” due to the possibility of toxic algae that may make the lake unsafe for people and pets.

City of Edmonds spokesperson Kelsey Foster said it is recommended that recreational users:

– Do not swim or boat in areas of scum

– Do not drink the lake water

– Keep pets out of the water

Fishing is not advised, she added.

According to Foster, a drone was flown around the shoreline of the entire lake Tuesday, and staff reviewed the footage Tuesday and Wednesday. “The bloom does not appear to be all that extensive or heavy, but this could change quickly, especially this time of year,” she said.

“There are two small locations where it appears that floating algae was present,” she said. “Algae blooms in the heart of the summer tend to be dominated by diatoms and green algae, but in the transition from summer to fall, blue-green algae (AKA cyanobacteria) often dominate algal populations prior to the lakes de-stratifying, typically in October/November.

“We will continue to monitor for increasing densities of those species of blue-green algae that are known to produce biotoxins, with anabaena flos-aquae and microcystis being the most common,” Foster added. Updates will be provided to the public as they are available.