Understanding Sources of Phosphorus and Trophic State in the Forbes Lake Water Supply

近年来，在加拿大大西洋地区的几个湖泊和水库中发生的蓝藻水华引起了公众的极大关注。 蓝藻水华频率明显增加可能是由于一些因素，包括气候变化和酸沉降水平下降。然而，增加的营养负荷仍然被认为是影响水华潜力的一个核心因素。 磷是淡水系统中典型的限制性营养物质，识别和控制湖泊流域内的磷源是防止蓝藻水华的关键第一步。 新格拉斯哥镇自来水公司的饮用水来自一个72公顷的水库，称为福布斯湖。 该湖从未经历过藻华，但最近对水处理厂操作的改变导致磷基腐蚀控制剂再循环回湖中。 公用事业公司和达尔豪西大学正在进行这项研究项目，以更好地了解与湖泊中额外的磷有关的风险，以及是否需要采取缓解措施来去除这种磷源。这项研究将涉及一个实地采样计划，旨在表征目前的磷水平和营养状态的福布斯湖，和流域模型的发展，以了解磷的各种来源的湖泊。这项研究的结果将指导公用事业公司做出与水源湖和水处理过程管理相关的关键决策。

The occurrence of cyanobacteria blooms in several lakes and reservoirs in Atlantic Canada in recent years has generated significant public awareness and concern. The apparent increasing frequency in cyanobacteria blooms could be due to a number of factors, including climate change and decreased levels of acid deposition. However, increased nutrient loading is still recognized as a central factor influencing potential for blooms. Phosphorus is typically the limiting nutrient in freshwater systems, and identification and control of phosphorus sources within the lake watershed is a critical first step in preventing cyanobacteria blooms. The Town of New Glasgow Water Utility sources their drinking water from a 72 ha reservoir called Forbes Lake. The lake has never experienced an algal bloom but recent changes to water treatment plant operations have resulted in the recycling of phosphorus-based corrosion control agents back into the lake. The Utility and Dalhousie University are undertaking this research project to better understand the risk associated with this extra phosphorus addition to the lake, and if mitigative steps need to be taken to remove this source of phosphorus. The research will involve a field sampling program aimed at characterizing current phosphorus levels and trophic state of Forbes Lake, and the development of a watershed model to understand the various sources of phosphorus to the lake. Outcomes from this research will guide the utility in making critical decisions related to management of both the source water lake and water treatment process.