Preparing for Fall Blooms (The Scummy Ones!)

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Harmful Algal Blooms

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Waterfowl Hunting Season and What it Means for Your Pooch

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The estimated 45,000 Wisconsin waterfowl hunters whose favorite hunting partner has four legs, a tail, and doesn’t mind swimming in cold water may want to take some water safety precautions for their furry friend this fall. While not widespread, toxicity from blue-green algae is still a concern for waterfowl hunting dogs in September and October.

Can blue-green algae still form blooms in the fall?

Blue-green algae are infamous for making a fall exit by forming blooms during warmer days and lake turnover events. Lake turnover is a natural phenomenon that occurs in the spring and fall when the cooler top and warmer bottom layers of a lake switch positions, causing the water to mix. Deeper water containing less oxygen and more decaying matter rises to the surface. While this temporary environment may be stressful to many aquatic organisms, blue-green algae near the surface can thrive because of their preference for warm water and ability to photosynthesize, produce oxygen, and fix their own nitrogen. With this advantage, blue-green algae can still form blooms in the fall.

Why should hunters be concerned about their dogs?

Hunting dogs might retrieve an animal from a location in a river, lake, or pond where higher concentrations of blue-green algae and their toxins are present. As dogs are retrieving from surface water, they may ingest impacted water incidentally as they carry a carcass while swimming, or intentionally as their thirst grows from rigorous activity.

What can hunters do to protect their dogs?

Hunters should:

  • Be on the lookout for potentially unsafe water conditions and avoid water that looks like green “pea soup,” appears to have spilled latex paint on the surface, is discolored, or has surface scum, foam, or algal mats.
  • Bring along a supply of clean, fresh water for their dogs to drink.
  • Prevent their dogs from submersing themselves in water that is clearly discolored or has surface scum, foam, or algal mats.
  • Stop their dogs from licking algae or scum off their fur after they swim.
  • Wash their dogs off thoroughly with fresh, clean water if they swim in discolored or scummy water.

After a potential exposure, hunters should watch their dog for signs of lethargy, loss of appetite, vomiting, diarrhea, or seizures. If their animal shows any of these symptoms, they should contact their veterinarian immediately.

Local health and tribal agencies can share this fact sheet with hunters to promote education about blue-green algae and dog safety.

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Below are popular questions the DPH HAB Program has been receiving this summer. We’re happy to share our standard answers.

Q: We’re planning on visiting Lake X this weekend with our kids and pets. Can you tell me if it has blue-green algae?

A:  Blue-green algae are a natural part of all water bodies in Wisconsin. They are of concern when they grow to noticeable levels, called blooms. There is no comprehensive list or map of water bodies with blue-green algae blooms in Wisconsin. The best thing you can do to keep yourself, your kids, and your pets safe is to look for and avoid high concentrations of blue-green algae, which may resemble green “pea soup” water, spilled latex paint, floating scums and mats, or otherwise discolored water. Always choose the clearest water possible to swim in. Remind kids not to swallow water while swimming, and bring along fresh, clean water for pets to drink. Visit this fact sheet to learn more.

Q: The temperature of the lake water was reading X degrees. Will blue-green algae form blooms in that temperature?

A: Blue-green algae can form blooms in a wide range of temperatures and have even bloomed under ice in winter in Wisconsin. While there isn’t one specific temperature that blue-green algae prefer, they typically form blooms during warm and sunny summer days when higher temperatures warm the water and plentiful sunlight leads to higher rates of photosynthesis. Other factors besides temperature can influence the formation of blooms as well, including rainfall and levels of available nutrients in the water. Since blooms can occur at any time, it’s important for lake-goers to be familiar with what blooms look like and avoid them. Visit this fact sheet to learn more.

Let's Get Social!

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This issue’s sample post and suggested accompanying photo:

It’s almost duck-hunting season! Did you know that Wisconsin has about 75,000 waterfowl hunters—the third highest number in the U.S.? About 60%, or 45,000, use dogs to retrieve their harvested ducks and geese. With blue-green algae still capable of forming blooms in the fall, hunters can keep their dog’s safety in mind by becoming familiar with potentially harmful water conditions. Visit this fact sheet to learn more:

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