HydroClient is a free web application for searching for, viewing, and downloading environmental time series data submitted by researchers around the world and maintained by CUAHSI's Water Data Center (https://www.cuahsi.org/wdc). Users can search for data by type, location, data source (e.g. U.S. Geological Survey), and time ranges. Users can view the data results with the Data Viewer Tool or download the data as a .csv to their local computer.