Water Quality FAQ

The Charleston Lake Association receives many inquiries about water quality each year.   Here is a sample of some of the questions along with our response.

1.  WHAT IS BLUE GREEN ALGAE AND WHAT ARE THE HEALTH RISKS?

Blue-green algae are microscopic, plant-like organisms that occur naturally in rivers, lakes and streams. Exposure to this algae can cause rashes, skin and eye irritation, allergic reactions and gastrointestinal upset. 

 

Blue-green algae are not normally visible in the water, but populations can rapidly increase to form a large mass called a bloom when conditions are favourable.   Blooms most commonly occur in late summer and early fall and thrive in areas where the water is shallow, slow moving and warm.  Algae blooms also pose a risk to fish and other aquatic species, because as algae dies off it sinks to the bottom and decomposes.  This decomposition process reduces oxygen levels in the water, limiting the available habitat for aquatic life.  Simple steps to prevent the growth of blue-green algae are:

  • use only phosphate-free products

  • avoid using natural or store-bought fertilizers on lawns

  • reduce runoff by maintaining vegetation 20 meters from the  shoreline

  • Pump out the septic tank every 3-5 years and inspect regularly​

Charleston Lake has had only one documented incident of Blue Green Algae.

This happened in 2000 in Charleston Village and was small and short lived.


We are now seeing Filamentous Green Algae. This algae although unsightly is

not Blue Green Algae and not harmful.  These billowing green blobs are usually 

seen in the spring and early summer, found just below the surface of the water

and eventually sinking to the lake bottom.

2. HOW DO ZEBRA MUSSELS AFFECT WATER QUALITY? 

Zebra mussels are an invasive species that has spread throughout the great lakes and most inland lakes in Ontario.  These mussels cause damage to the lake ecosystem plus their sharp shells can easily cut bare feet. To further reduce the risk of introducing additional mussels to the lakes, boats, fishing gear, and other recreational equipment entering from a different water body should always be cleaned and inspected before entering the lake.

3. WHAT ARE THE MAIN SOURCES OF PHOSPHOROUS IN THE LAKE? 

Most phosphorus in a lake comes naturally from the soil, plants, animals and precipitation in and near the lake. But human activity can significantly contribute extra phosphorus to a lake.   The common sources of phosphorus, which can be controlled or influenced by lake residents:

  • Fertilizers: neither chemical nor natural fertilizers (manure) should be used near the lake or other water such as creeks. These fertilizers contain phosphorus as one of their components.

  • Soaps and cleaners: many soaps and cleaners contain phosphorus (ie. phosphate). Buy only phosphate-free products. 

  • Septic tanks: Maintain your septic system and remember to have your tank pumped out every 3 to 5 years. 

  • Stormwater and erosion: Make sure that your property has as little hard surface as possible.  Maintain vegetation like trees, flowers and shrubs within 20 meters of the shoreline to absorb rainwater runoff before it enters the lake. 

The phosphorous levels in Charleston Lake have improved, which means now that Charleston Lake is
categorized as an Oligotrophic lake.  For clarification:

  • Eutrophic Lakes are a nutrient enriched lake high in phosphorous and nitrogen; poor in clarity and little

  • or no deep water oxygen.

  • Mesotrophic Lakes are moderately enriched in nutrients.

  • Oligotrophic Lakes are nutrient poor lakes; deep, clear, cold, oxygen enriched.