Cherry Creek State Park officials announced the presence of toxic blue green algae on Cherry Creek Reservoir Saturday, warning people to be careful about contact with the water, but some people on social media said the warning should have been posted earlier and some reported getting sick.

Officials made the announcement on social media Saturday, warning that the algae can cause illness in people and pets. The Facebook post was met with several comments claiming the algae was on the water days before state park officials made any announcements. Other commenters claimed they had been told the water was safe when algae was present, only to get sick later. 

Commenter Ashley Armour said state park officials should have posted a week prior, saying she was at the reservoir on Wednesday and “it was disgusting.” 

Another poster using the moniker Kia Abdool called the timing of the post “extremely disappointing,” adding that a ranger told her on the day the post was made that the water was safe.

“I asked the ranger (Saturday) and he said and I quote – ‘the water was tested and there was no bacteria’,” Abdool wrote in the comments. 

Christie Vasquez said in the post comments that her family got “very sick” after going to the reservoir Thursday. 

“I wish someone would’ve given us a warning when we entered the park … We got all set up and as we were walking towards the water, it was the most awful smell,” Vasquez wrote in the comments. “I had no idea it wasn’t safe to swim in and my oldest, myself and my son have been very sick since Saturday.”

The Denver Gazette attempted to reach the authors of those social media posts, but they did not reply for comment. 

Colorado Parks and Wildlife spokesperson Kara Van Hoose said a test of the algae blooms on Thursday did not show any toxins, but staff put up signs near the two places where algae was seen — Dixon Grove and West Shades — as a precaution telling people not to swim.

Cherry Creek Reservoir is currently at a yellow, or caution, status, Van Hoose said, meaning water recreation is allowed at ones’ own risk and the bloom is not emitting toxins. 

However, people should not drink or swim in the water and, if contact with the water is made, people are urged to shower thoroughly afterward, officials said on Facebook.

Current information about the water quality can be found on the Colorado Department of Health and Environment’s website. 

Algae blooms are common during the summer because they are caused by warming water temperatures and lack of water movement, Van Hoose said. When water sits still, bacteria forms as algae, she added. 

While not all algae blooms are toxic, humans and pets should take precaution around them regardless.