People and pets are warned to stay away from blue-green algae being seen along shoreline.

Conditions ideal for blue-green algae intensified Tuesday with watershed experts calling it a “perfect storm” for the menace that manifests as streaks of green slime. The hot, humid weather coupled with a calm that settled on the lake early Tuesday morning fueled the algae bloom reported at shoreline areas all around the lake.

Watershed Manager Kevin Olvany warned people not to swim in the lake where there are algae-bloom conditions. People should also keep pets out of the lake due to algae toxins. Pets are especially vulnerable to blue-green algae since they drink a lot of water when in the lake. The algae also can concentrate on their fur, and they can ingest large quantities when they groom themselves.

Olvany said Tuesday morning there was a “dead calm” on the lake. “At 7:30 when the sun came up it was really popping up at the shoreline,” he said.

Olvany was taking multiple calls from people all around the lake about the bloom. He spent much of Monday out on the lake and inspecting shoreline areas. Tuesday afternoon, he said the north end of the lake around Kershaw Park looked a bit clearer than other areas but people should still use “extreme caution” about going in the water.

Overall on the lake, the bloom is “definitely popping,” Olvany said.

Lab results on sampling last month confirmed some blooms are toxic — so to be safe, people and pets should stay away from any bloom-like signs. Conditions can change very quickly on the lake with wind and temperatures affecting location and intensity of blooms.

The heat was expected to last through Wednesday with a high of 91 degrees. Temperatures are then expected to drop down into the 70s for the rest of the week. The long-term forecast calls for temperatures rising back into the 80s next week.

In mid-August, signs of blue-green algae began appearing in a few isolated locations on both sides of the lake. A blue-green algae bloom reported Friday, Aug. 24, on the lake closed the swim beaches at Onanda and Deep Run parks. Canandaigua Lake Watershed Association confirmed that certain shoreline areas showed concentrations of algae containing the presence of cyanobacteria, the toxin of Harmful Algal Blooms (HAB).

Last Thursday, just in time for the long Labor Day weekend, the beaches got a clean bill of health to reopen. The beaches close after Labor Day, though with the hot weather people will be tempted to swim from areas around the lake and Olvany said that is a concern.

Canandaigua and Seneca lakes experienced their first toxic algae blooms in summer 2015. Algae blooms have continued to be a problem to varying degrees since then on the two lakes, which joined a growing list of waterways nationwide plagued by harmful algae blooms.

Frustration over persistent blue-green algae blooms in the Finger Lakes has numerous organizations and agencies working together on ways to mitigate the problem. Monitoring has also ramped up around the lakes with programs to engage volunteers in collecting water samples for testing. People are urged to report suspected blue-green algae to help in the effort. 

According to the state Department of Health, exposure to any HABs can cause health effects in people and animals when water with blooms is touched or swallowed, or when airborne droplets are inhaled. This is true regardless of toxin levels; some blue-green algae produce toxins, while others do not. Exposure to blooms and toxins can cause symptoms such as diarrhea, nausea or vomiting; skin, eye or throat irritation and allergic reactions; or breathing difficulties. People and pets should avoid contact with blooms, and should rinse off with clean water if contact occurs. For more information, go to www.health.ny.gov/harmfulalgae

To report suspicious blooms on Canandaigua Lake, send photos along with location and description of the conditions you are seeing to: HABs@canandaigualakeassoc.org.