Water Safety Plan and Risk Assessment for Norrvatten from Catchment Area to Raw Water Intake

Sammanfattning

This thesis explores the implementation of Water Safety Plans (WSPs) and risk evaluation methodologies, with a specific focus on Norrvatten's water management practices in the Upplands-Bro municipality catchment area in Sweden. The study area is only partially covered by the existing water protection area boundary, yet it is crucial as the water flows into the Görväln drinking water treatment plant in Lake Mälaren, given that the catchment area for Lake Mälaren is extensive, with a smaller area covered by the current water protection area zone. The study combines a comprehensive review of World Health Organization (WHO) guidelines, an overview of global WSP examples, and a case study of the Upplands-Bro area to assess current practices and identify opportunities for improvement in water safety management. While Norrvatten's practices align significantly with WHO guidelines, there is potential for enhancement, especially in formalising the WSP approach and refining risk assessment methodologies. This research explores the comparative effectiveness of WSPs, the EU Directive 2020/2184, Swedish legislation, and current Norrvatten practices highlighting the challenges such as the complexity of accurately identifying and quantifying the study area’s microbiological and chemical risks and the difficulty of prioritising risks based on their impact to Norrvatten’s raw water source. Key findings underline the necessity of continuous improvement in WSP implementation, improved data collection and analysis, and effective public communication in water safety management. The thesis concludes with recommendations for Norrvatten, offering suggestions for future research, such as developing advanced risk assessment tools using quantitative microbial risk assessment (QMRA) and implementing water safety plans and risk matrices for other catchment areas that are feeding Norrvatten’s raw water. Moreover, evaluating the long-term impacts of WSP implementation on water quality and public health outcomes using a proactive approach and handling future threats such as climate change, urbanisation and environmental changing conditions. Additionally, the current water protection area boundaries should be expanded to incorporate the study area catchment and to address the misalignment between the administrative boundaries and the hydrological realities. Finally, to strengthen collaboration with stakeholders, related authorities and consumers.