Ökade stängningar av Göteborgs råvattenintag - En analys av saltvatteninträngning, bakteriehalter och väder

Abstract

Gothenburg’s drinking water supply is highly dependent on raw water from Göta älv, which is a source that is increasingly challanged by climate change, agriculture and urbanization. This study aims to understand the causes and timing of intake closings at Lärjeholm by analyzing raw water quality data from Kretslopp och vatten and metrological data such as temperature and precipitation from SMHI from 2001 to 2025. The main focus on saltwater intrusion, bacterial contamination (particular ly E.coli), and weather-related parameters. By using these data, seasonal patterns and trends were identified and then analyzed. The results show that intake closures are often linked to elevated E.coli levels indicating fecal contamination, or high con ductivity, indicating saltwater intrusion. This study has been able to correlate 85% of the closings to bacteria and saltwater intrusion while 15% remain without clear cause. The findings emphasize the importance of continuous monitoring, further re search and development of solutions to ensure a sustainable drinking water supply for Gothenburg.