The Swedish Defence Research Agency (FOI) and the Swedish Mapping, Cadastral, and Land Registration Authority (Lantmäteriet) have developed a draft risk assessment method, MEGS, to evaluate the impact of making geodata available as open data on Sweden's security. This work, Method for Risk Assessment of Geodata when Making them Available as Open Data, undertaken between 2024 and 2025, aligns with the Open Data Act, which came into effect in 2022. The law requires that risk assessments account for aggregation, where potential combinations are infinite. Risk assessments often rely on evaluating probability and consequences. However, for complex risks, this approach is not applicable since there is no data to assess the probability. Since the security of Sweden is involved, with no clear criteria or defined consequences, the method introduces relevance instead of probability. For assessing consequences, the project has tested developing consequence levels based on interpretations of Sweden's security. Relevance, consequence levels, and their criteria for Sweden's security are used in the proposed risk assessment method, MEGS. The report outlines MEGS's development and design considerations, with a separate publication detailing its application Proposed Process Support for Risk Assement of Geodata when Making them Available as Open Data - A Collaborative Effort by Government Agencies