Horseshoe Lake Property Owners Association (HLPOA)

Facilitating Algal Bloom Identification,  Reporting and Communications


Normally blue-green algae are not visible in the water, but when conditions are favourable, algal populations can rapidly increase to form a large mass or scum in the water called a bloom. Blooms most commonly occur during the warmer weather of late summer and early fall.


Blue-green algae thrive in areas where the water is shallow, slow moving and warm, but they may also be present in deeper, cooler water. One key factor affecting the growth of blue-green algae is the amount of available nutrients such as phosphorus and nitrogen. In the Haliburton Highland water bodies, phosphorus tends to be the nutrient that controls how much algae can grow.

What Can You Do To Help?

While some of this information has been presented above, the impact of Algal Blooms or Blue Green Algae Blooms on all of us is so significant that it bears repeating.  It is also a reminder that only together can we ensure the health of our lake and protect it from dangers such as Algal Blooms.

HOW CAN BLUE-GREEN ALGAL BLOOMS BE REDUCED OR PREVENTED? Human activities can promote the growth of blue-green algae. For instance, agricultural, urban and stormwater runoff, effluent from sewage treatment plants and industry, and leaching from septic systems can elevate the levels of nutrients in water bodies, which can promote algae growth. Reducing or eliminating nutrient inputs from these sources is a proactive way to reduce the occurrence of blue-green algal blooms.

Take these simple steps to prevent the growth of blue-green algae:

  • use phosphate-free detergents, personal care and household cleaning products
  • avoid using fertilizers on lawns, especially fertilizers that contain phosphorus
  • maintain a natural shoreline on lake and riverfront properties
  • reduce agricultural runoff by planting or maintaining vegetation along waterways and minimize fertilizer use, and
  • check septic systems to ensure they do not leak into the water source.

Ontario is taking action to reduce blue-green algal blooms. The Clean Water Act, Great Lakes Strategy, Lake Simcoe Protection Act, and other programs promote actions that will reduce the amount of nutrients entering Ontario water bodies. Ontario will continue to work to better understand and reduce harmful and nuisance algal blooms. Find more information on source and lake protection programs in Ontario at

Be Cautious and If you suspect a blue-green algal bloom, assume toxins are present and :  

What To Do If You Suspect a Blue Green Algae Bloom

1. Take pictures

2. Notify MOECP Peterborough office directly | 705-755-4300 or the general tip line at 1-866-663-8477

3. Notify the HLPOA at so that we can let members on the lake know

4. Notify your municipal government

5. Tell your neighbours

 6. Do not swim in the lake or let pets or any animals swim or drink from the lake until assessment is complete through the MOECP

 7. Do not allow water from the lake to enter your house/cottage

  • Most water treatment systems will not safely treat water with a blue green algae bloom
  • Boiling or chlorinating the water can release toxins into the air
  • Even UV filters will not safely treat water which contains a blue green algae bloom
  •  Purchase forms of spring water for personal use

8. Stop using the water and seek medical attention if symptoms such as skin, eye or throat irritation, allergic reactions or breathing difficulties occur while in contact with untreated surface waters.

9. Do not eat fish caught in the water body.

10. Avoid activities that increase exposure to toxins during algal blooms; call the local Health Unit for information and follow their advice.

Blue Algae - The Good, The Bad and The Ugly - video presentation

Algal blooms are of concern to all Horseshoe and Mirror Lake property owners.  Environment Haliburton recently sponsored an Enviro-Cafe on the subject.  Dr. Elizabeth Favot, PhD, Assistant Lake Stewardship Coordinator, Federation of Ontario Cottagers' Associations (FOCA) gave the presentation on February 9th.  Participants had the chance to ask questions.  

Check out this link to a YouTube recording of the presentation:

Horseshoe Lake Property Owners Association
P.O. Box 3, Minden, Ontario K0M 2K0

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The HLPOA acknowledge the lands and waters on which we meet, are the traditional homelands of the First Nation, Métis and Inuit peoples. Our beautiful lakes are fed from the north and flow to the south. We therefore acknowledge the Algonquin and Mississauga peoples as well as the governance of the Williams Treaties. We wish to express gratitude to Mother Earth, the resources we are using, and honour all Indigenous people who have been and continue to live on these lands.


Horseshoe Lake Property Owners association is committed to fostering a culture of diversity and inclusion in which every member, their family and friends are treated with respect and dignity.

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