Cosmo Dog Park in Gilbert

Algae on the lake at Cosmo Dog Park in Gilbert has pet owners upset. The Town says the water is safe, but some owners say they won't let their dogs near it.  

“Filthy,” “disgusting” and “gross” are some of the words people are using to describe the lake at Cosmo Park, named after Gilbert’s first police dog.

The entire 17-acre park built in 2006 near Ray Road and Loop 202 caters to man’s best friend with amenities such pet drinking fountains, dog washing stations and a dog beach with a dock that canines can jump from into the man-made lake.

“Water is so nasty at Cosmo,” wrote one woman on a social media site that generated over 70 comments last week about the lake’s condition. “Foamy and all green.... sure don’t want my dogs getting sick from that water so we haven’t been in a long time.”

Echoed another woman who said she doesn’t take her dogs there either: “It isn’t worth risking our dogs’ lives.”

The flurry of comments came after someone posted an August news video of three women who lost their pets after they had separately visited Lady Bird Lake in Austin, Texas. The dogs played in the lake and died shortly after coming into contact with the toxins from blue-green algae in the water.

The man addressed the post to “Cosmo Dog Park goers” and asked for their thoughts.

Gilbert, however, stood behind the lake’s safety.

“To this date, the Cosmo Lake has shown no levels of any of these substances, which are known to be harmful to animals,” said town spokeswoman Jennifer Harrison. “We are committed to keeping all lakes as safe as possible.”   

At the lake last week, opposite from the fenced dog-play areas, the water was nearly blanketed with a green-hued growth.

“Typically, the matter on top could be other types of algae, other biological materials, debris, etc,” Harrison said after she viewed photographs taken by Gilbert Sun News. “There is ‘algae’ in the lake but it is important to note that there are different types of algae; the blue-green algae is the one typically causing problems with pets.”

Not all algal blooms are harmful and less than 1 percent of algal blooms actually produce toxins, according to the National Oceanic and Atmospheric Administration.

Blue-green algae can vary in color and appearance and may look like pea soup or spilled green paint on the surface of the water, green or yellow streaks or scum on the surface of the water or green globs or streaks floating below the surface.

“Regardless of blue-green algae, Cosmo Lake is filthy,” one man wrote on the social media site. “Think about it this way, would you swim in the water and risk ingesting it? I understand dogs have a stronger system to fight off some things humans can’t (but) I just choose not to risk it.”

Harrison said the town’s lakes, use reclaimed water in a park and are professionally maintained and treated by the company H2Ology.

“H2Ology is on site at Cosmo twice a week to clean and test the levels of PH, nitrates, algae and general bacteria in the lake,” Harrison said.

“The results of the test are sent to the town of Gilbert within a week, and the vendor works with our parks and recreation staff for any additional treatments needed,” she added.

She noted that H2Ology also uses an aquatic sunscreen that blocks the UV rays and slows down algae growth.

Periodically when the lake is treated, it is barred from use for a minimum of three days, according to Harrison.

“During that period, we tape the lake off with caution tape and place signs at the lake and other places around the park,” she said.

She noted the town was proud of the fact that Cosmo Park has over 600,000 visitors annually and was named by Phoenix Magazine as the Valley’s best dog park on multiple occasions.

Cosmo Park also includes amenities for humans such as armadas with barbecue grills, a play area and a lighted basketball court.

Although it may not be blue-green algae and the water is deemed safe by the town, one man claimed his 3-month-old yellow Labrador Retriever got sick a year ago from the water with coccidia, an intestinal parasite.

Haven’t gone back to that sh**hole (literally) since,” he wrote.

A woman said her dog got sick with coccidia from the lake as well.

“I’ve heard of dogs getting sick from bacteria in the water at Cosmo so I haven’t taken them,” wrote another while still another warned dog owners not to take their pets to the dog park’s lake.

“My dog thankfully didn’t die from that water but he got extremely sick and almost did,” she wrote, “It’s so gross.”

The lake’s appearance apparently is not a recent phenomenon.

A Chandler resident wrote on Yelp last year that she loved Cosmo Park but no more.

“They rarely clean the water portion to the point where every time my dog goes swimming she’s sick now,” she wrote. “I truly only came here for the water area but now I have to stay on the dry side so my dog’s not sick for a week after. They used to really take care of this place and now it’s basically a dump.”

Not everyone, though, has had a bad experience with the lake.

“I have taken my purebred Rottweiler to Cosmo dog park lakeside 25 or so times over the last couple years…and he has been healthy besides a small cold once,” wrote one woman, adding:

“Why would they have a dog park specifically designed for dogs and not check the lake consistently? I might be naive but if there was a legitimate problem, it would get shut down.”

Town Councilwoman Brigette Peterson also attested to the lake’s safety.

“The water at Cosmo is circulated and tested on a regular basis,” she wrote. “I let my dog swim there... she’s a 2-plus year old Golden Retriever. The lake at Cosmo was designed specifically for dogs to use, humans are not allowed.

“There are times of the year that the water looks horrible and it’s due to other factors but still regularly tested and safe,” Petersen.

The Texas deaths of the dogs from blue-green algae weren’t the only cases reported this year, although none have been reported in Arizona.

Two women in North Carolina reportedly took their three dogs into a pond near their home in August for some fun time but within hours the dogs got sick and died, poisoned by blue-green algae, according to a veterinarian.

And a Georgia woman, also in August, reported her dog was left brain-dead after coming into contact with blue-green algae at a lake.

Blue-green algae or cyanobacteria is most likely to thrive in bodies of fresh water — lakes, streams and reservoirs — when the weather is over 75 degrees and sunny and is incredibly toxic for pets and pose risks to humans, according to experts.

Currently, no government agency publicly tracks toxic algae outbreaks nationally, according to The Environmental Working Group, which has been monitoring and mapping news stories of toxic algae blooms across the country since 2010.

The nonprofit reported many bodies of water nationwide are being threatened by algae blooms, which have surged between 2010 and 2019, fueled largely by polluted runoff from farms and exacerbated by climate change.

In 2014, toxic algae bloom reportedly left 500,000 residents in Toledo, Ohio without drinking water for three days

Arizona Department of Environmental Quality, which monitors the state’s recreational lakes for algal toxins and when algal blooms are reported, recommends people stay away from algae and scum — and especially keep children and pets away from algae in the water or on the shore.