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Colorado health officials warn about toxic algae blooms as 4 water sites show dangerous concentrations

While algae is an important part of aquatic food webs, some types can produce toxins that may cause negative health impacts for humans and pets, according to health experts
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Posted at 11:55 AM, Aug 01, 2023

DENVER – State health officials are asking Coloradans to be aware of toxic, blue-green algae when recreating in reservoirs and lakes this summer as the warmer weather is producing blooms that could be harmful to people and their pets.

Already this year, three water sites across the state have been temporarily closed to recreation due to dangerous concentrations of these toxic, blue-green algae blooms, according to the Colorado Department of Health and Environment (CDPHE). Eight other sites are awaiting confirmation from a state lab about potential blooms in their water.

Swimming, paddleboarding and wading are currently not allowed near the marina and West Shades area of Cherry Creek Reservoir due to elevated levels of microcystin, an algal toxin, a spokeswoman for Colorado Parks and Wildlife (CPW) said Sunday. Boating and fishing were still allowed.

Recreation is also currently prohibited at Barr Lake, Dewesee and Road Canyon reservoirs, data from the CDPHE shows.

Reservoirs across the state, including Jumbo, North Sterling, Jackson, Stagecoach, Beaver Creek, La Jara, and Vega were among the sites with a potential bloom reported, according to the CDPHE. Blue Haron Lake was the only lake as of Tuesday that was also awaiting test results for algal toxins.

If you'd like to check for algae bloom concentrations at any of these sites for yourself, click here and select the "Recent conditions" tab.

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The map above shows recent toxic algae conditions for select water bodies in the state.

At Vega Reservoir, in Colorado’s Western Slope, visitors were encouraged to avoid any activities in the water where algae was visible, and to be especially mindful when walking pets near the reservoir and not let them drink the water or lick/ingest dried scum along the shoreline, as the blue-green algae can be toxic to pets.

“If accidental exposure does occur, do not let your pet lick their fur or paws. Rinse them thoroughly with potable water and wear gloves for your own protection if possible,” CPW officials said.

Coloradans will be able to tell if an algal bloom is harmful if it meets the following criteria, according to state health officials:

  • Resembles thick pea soup or spilled paint on the water.
  • Looks discolored — generally green, red, gold, or turquoise but typically not stringy or mustard yellow (the latter is probably pollen).
  • Has foam, scum, or algae mats.
Toxic algae is closing some Colorado bodies of water. Is this normal?

What to do you if you or your pet comes into contact with blue-green algae

Algae are an important part of aquatic food webs, but some types of blue-green algae (also called cyanobacteria) are capable of producing toxins that may cause negative health impacts for humans and pets at elevated concentrations, CPW officials said.

If your dog gets into a harmful bloom, health officials advise that you rinse your pet off immediately with fresh, clean water. If you, a friend or a family member come contact with the bloom, immediately wash with soap and water.

If your pet has been poisoned by the algae, it’ll show symptoms anywhere from 15 minutes to several days, including diarrhea or vomiting, weakness or staggering, drooling, difficulty breathing and convulsions or seizures, according to health officials.

If your pets are exposed to the water and experience those symptoms, contact your veterinarian immediately, as these toxic algae can kill your pet.

Humans poisoned by the algae could develop a skin irritation, diarrhea, stomach pain, fever, headache, and a sore throat. Exposure to these toxins can also harm a person’s liver and kidneys and affect their neurological systems, according to the U.S. Centers for Disease Control and Prevention (CDC).

How you can play your part to mitigate toxic algae blooms

While algal blooms are common in the summer when water temperatures rise, there are some things you can do to not make them worse, state health officials say.

Picking up after your pet and properly disposing of their waste prevents nutrients found in excrement (such as nitrogen and phosphorus) from entering waterways, which contribute to algae blooms.

Refraining from using too much fertilizer is also one way in which algal blooms can be kept at bay.

If using de-icers, make sure they don’t contain urea (this information will be on the de-icer bag), health officials said.

To learn more about blue-green algae, head to the CDPHE’s website.

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