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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.

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