What levels of phosphorus are safe for plants and animals that live in Canadian waters?
Total phosphorus (TP) levels vary widely in Canadian fresh waters. Some systems naturally have very low TP levels and may be described as oligotrophic (low nutrient status). Other systems naturally have high TP levels and are described as eutrophic (high nutrient status). Because of the wide variability of natural phosphorus levels in freshwater systems, it is not possible to establish a single meaningful guideline for phosphorus. Instead, a guidance framework has been developed to allow site-specific management of phosphorus. The framework uses trigger ranges, which are ranges of desired phosphorus level for a specific freshwater system. The appropriate trigger range is determined according to baseline data and management objectives or goals for the system. If phosphorus levels in the system exceed 50 percent of the baseline level or the upper limit of the trigger range, there may be an environmental problem and further investigation is triggered. The trigger ranges for Canadian lakes
