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Blue-green algae closes Cherry Creek swim beach

The beach will be closed until algae levels are safe again.

DENVER, Colorado — The swim beach at Cherry Creek State Park has temporarily closed after Colorado Parks and Wildlife (CPW) said they have detected a high level of algae. 

The blue-green algae, also called cyanobacteria, can harmful to both humans and dogs, CPW said.

They were found at the swim beach as well as other areas of the park where CPW said they have put up signs warning visitors not to let kids or dogs play in the water. CPW also recommends avoiding contact with the algae. 

The algae have not been detected in the stream at the off-leash dog area in the park, CPW said.

RELATED: Be cautious of potentially harmful blue-green algae this summer

Blue-green algae is a bacteria found in non-flowing freshwater that can be fatal to animals if ingested. The algae naturally occurs in aquatic ecosystems and can appear rapidly – especially during the summer with hot weather and in slow-moving water bodies, such as lakes, according to the Colorado Department of Public Health and Environment (CDPHE). 

"Some algal blooms can contain cyanobacteria –often referred to as blue-green algae," the city said. "While the vast majority of algae often seen in ponds and lakes during summer months are not toxic, cyanobacteria can produce toxins, which can be harmful to dogs and humans at elevated levels." 

>Watch above: Toxic blue-green algae a growing threat to dogs

At lakes and ponds where dogs are allowed to enter the water, people should practice caution if algae are present. 

The city said Anglers should also exercise caution and follow state recommendations to clean any caught fish thoroughly and to discard guts appropriately.

According to the CDPHE, harmful algae blooms often have the following characteristics: 

  • May look like thick pea soup or spilled paint on the water's surface. 
  • Can create a thick mat of foam along the shoreline.
  • Usually are green or blue-green, although they can be brown, purple or white. 
  • Sometimes are made up of small specks or blobs floating just at or below the water's surface

Harmful algae blooms are not:

  • Long, stringy bright green grass strands that feel either slimy or cottony.
  • Mustard yellow (this probably is pollen).

The swim beach will reopen once tests show that the conditions are safe, according to CPW.

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