Updated on May 17, 2022, the CRHQ is a cartographic tool that brings together ecological information and knowledge on aquatic ecosystems in Quebec to support decision-making. It provides a hierarchical framework for mapping and characterizing aquatic ecosystems based on the processes that govern their functioning. First of all, it provides aquatic ecological units (AEUs), which correspond to portions of the surface hydrographic network that present a certain homogeneity in their physical characteristics that condition aquatic biotopes. The CRHQ also includes information on the hydro-geomorphology, hydraulics, physico-chemistry and hydrology of aquatic ecosystems that are associated with reference points distributed on the hydrographic network. To access the files, which are hosted on an FTP site, it is recommended to use either FileZilla (https://filezilla-project.org/) or Internet Explorer.**This third party metadata element was translated using an automated translation tool (Amazon Translate).**