Visitors to Howard Eaton Reservoir in North East Township, as well as several other waterways in the area, may have noticed red and white signs with a circled and crossed image of a dog. It’s not a “No Dogs Allowed” sign, but rather a sign warning pet owners that toxins may be present in the water at levels harmful to animals.

Just what is creating the toxins? A tiny organism called Cyanobacteria that creates a blue-green harmful algae bloom, said Breanna Adams, director of Environmental Health Services at the Erie County Department of Health in Pennsylvania.

When the algae breaks down, it releases several toxins, such as microcystin, saxitoxin and anatoxin-A, Adams said.

These toxins sometimes affect the skin. When ingested, they may cause vomiting; they can also affect nerves causing weakness, staggering, convulsing, difficulty breathing and disorientation — or the toxins may affect the liver causing jaundice, liver disease or death. Symptoms can progress with animals very quickly.

Dogs are particularly at risk if they swim in or drink from bodies of water where the blue-green algae is prevalent.

Blue-green algae is a world-wide problem, Adams said. A harmful algal bloom is fairly easy to spot. It looks like spilled paint or pea soup on the surface of the water. “The scary part is that you can’t see the toxin,” Adams said.

Eaton Reservoir and other bodies of water in which the algae has been detected are tested once a week to determine if the toxin levels exceed a dog’s threshhold, Adams said. “A dog has a very low drinking water threshhold for the toxin,” she said.

For dogs, 0.2 parts per billion is considered dangerous, while for adult humans, the threshhold is 1.6 parts per billion. Nevertheless, anyone who is immune compromised or has open cuts or sores should be aware of the risk of toxins in the water.

“Dogs are our best friends and how they use the water is why their threshhold is so low,” Adams said. She noted that not only do dogs drink the water and swim at mouth level, they lick their fur after swimming.

“Any water is drinking water for a dog,” she added. “It is because of the way that dogs use the water, that the signs are up.”

Signs like this are posted at bodies of water where the blue-green algae has been found.

The problem is fairly widespread through the area. The Regional Science Consortium tests the water at 20 sites in Erie County, Pa., but the problem extends beyond state lines. The Chautauqua County Department of Health and Human Services also monitors beaches and bodies of water for harmful algae blooms and posts closures immediately.

The Erie County Department of Health’s website has a link to an interactive Google map that shows beach sampling results, swimming advisories at Presque Isle State Park and Freeport Beach in North East. The map also shows warnings about Harmful Algal Blooms. The Chautauqua County Department of Health and Human Services website has a link to a U.S. Geological Survey map that offers Great Lakes NowCast status for Ohio, Pennsylvania and New York. They also post all beaches in Chautauqua county that have blue-green algae closure notifications.

Adams said the bacteria tends to multiply and create algae blooms when the water heats up or is stagnant. Also, they are impacted by nutrient loading, such as when levels of phosphorus increase.

“We’re checking things that run into the water,” Adams said. “Runoff from farms and other sources are definitely part of the problem. We really need to be aware of what we put into our waterways.”

Eton Reservoir in North East Township, Pa., is a favorite fishing and recreation place. As with many other waterways in the area, blue-green algae has been discovered in its waters.