Updated on May 17, 2022, the CRHQ is a cartographic tool that brings together ecological information and knowledge on aquatic ecosystems in Quebec in support of 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 (UEAs) that correspond to portions of the surface hydrographic network that have 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 over the hydrographic network. To access files, which are hosted on an FTP site, it is recommended to use either FilleZilla (https://filezilla-project.org/) or Internet Explorer.**This third party metadata element was translated using an automated translation tool (Amazon Translate).**