ETC DI REPORT 2025/05 Ongoing initiatives for once-only publication of High-Value Datasets

This report examines the ongoing European initiatives and technical alignment efforts supporting the once-only publication of High-Value Datasets (HVDs). It focuses on environmental data-sharing frameworks, primarily those established under the INSPIRE Directive, and compares them with the data sharing requirements set out in the High-Value Datasets (HVD) Implementing Regulation adopted under the Open Data Directive. Following the initial reporting deadline in the scope of the HVD Implementing Regulation in February 2025, the study presents a detailed preliminary analysis of environmental HVDs submitted by Member States focusing on the noise (END), marine (MSFD), and water (WFD) domains. It incorporates comparative metadata searches conducted in April and October 2025 to monitor implementation progress and track data fluctuations within the European Data Portal (EDP). The report identifies key factors that hinder data discoverability, including inconsistent metadata practices and the heterogeneous use of keywords. It also sets out strategic recommendations, such as adopting harmonised metadata guidance and promoting the consistent use of standardised vocabularies and directive-specific keywords, to support a unified, interoperable approach to publishing environmental HVDs across Europe.