LST P111 Risk sensitivity load — GIS support for small sewers

In order to assess the sensitivity of a recipient to phosphorus loads, the Water Agency’s calculated condition for those receiving waters that do not achieve good ecological status with respect to the nutrient quality factor is set in relation to the proportion of the total phosphorus load on the receiving waters coming from small sewers. The method is based on expert judgement and is a way of applying the EQS for surface water. Of approximately 22 000 water bodies in Sweden, about 2000 has a phosphorus treatment. By using the source distribution of the phosphorus load, a certain balance of equity is included in the risk assessment. Will 25 % or more of the load from small sewers be judged to be able to contribute to meeting the environmental quality standard, high performance requirements for sewage. The purpose of the GIS support is to create conditions at a national level for a reasonable, legally certain and more consistent assessment of the level of protection under Chapter 2, Section 3 of the Environmental Code when examining small sewers. The GIS support consists of maps showing the risk of impact on recipient/exposure point due to load from a drain. The maps have been produced through risk assessments based on the legislator’s instructions on criteria for assessing the high/higher level of protection for the entire surface of Sweden.