USGS celebrates 15 years of WRTDS for water-quality science and management

First published WRTDS applications across continents and countries, highlighting its global adoption. Colors are used to clarify the boundaries between neighboring countries. Sources/Usage: Zhang et al. 2026, ES&T, CC-BY 4.0.

Since its inception in 2010, the Weighted Regressions on Time, Discharge, and Season (WRTDS) method has grown into a state-of-the-art tool informing water-quality science and management worldwide. The free R package EGRET (Exploration and Graphics for RivEr Trends) makes WRTDS analysis easily accessible and has been downloaded more than 80,000 times by users across the U.S. and worldwide. The flexible, data-driven framework of WRTDS accounts for factors like streamflow variability and seasonality. Two recent publications co-authored by scientists at the USGS, the University of Maryland Center for Environmental Science, and the Chesapeake Bay Program reflect on advancements in WRTDS over the last 15 years, including its growing application to water-quality science and management challenges worldwide. For more information, contact University of Maryland/Chesapeake Bay Program scientist Qian Zhang or USGS emeritus scientist Robert Hirsch.