Robert M Hirsch

My main interest is improving the analysis of hydrologic data, particularly streamflow data and surface water quality data.  My major recent contributions are the EGRET software (Exploration and Graphic for River Trends) and the publication of "Statistical Methods in Water Resources" 2020.  The pdf and the hard copy of this text are available at


I am a research hydrologist.  The focus of my research is the description and understanding of long-term variability and change in surface-water quality and streamflow.  I develop and apply new statistical tools to help characterize these changes to gain the best possible understanding of the nature of the change and its implications from a policy perspective (for example with respect to water quality improvement, ecosystem restoration, flood hazard mitigation, water supply planning, or provision of in-stream flow).  I am the lead developer  of a software package called EGRET (Exploration and Graphics for RivEr Trends) which is now an approved USGS model (written in R - an open source computer language).  It is available from CRAN and is described on our EGRET project web page at  The statistical method (Weighted Regressions on Time, Discharge, and Season - WRTDS) has been used in a number of studies of water quality trends in the US (Chesapeake Bay Watershed, Mississipi River Basin, Lake Champlain Basin, and elsewhere) to describe and better understand changing concentrations and fluxes of nutrients in river systems.  There are also tools in the package and on the web page for analysis of long term trends in daily streamflow.  

My other major recent contribution is the publication of "Statistical Methods in Water Resources" the 2020 edition.  The authors are Dennis Helsel, myself, Karen Ryberg, Stacey Archfield, and Ed Gilroy.  This text book builds on the sucess of the 1992 version authored by Dennis Helsel and myself.  In addition to the book being available free from the USGS as a pdf ( it is also available in a printed version of Statistical Methods in Water Resources as a hard back book at  In addition to the pdf and the printed book, the text has on-line resources which include all of the data sets used as examples in the book, all of the R code used in the analysis of those data, and all of the R code used to produce the graphics in the book.  We hope the book will be used in many university courses and USGS courses on statistical analysis of water data.


Recent Accomplishments


B.A. in Geology from Earlham College, 1971

M.S. in Geology from the University of Washington, 1974

Ph.D. from the Johns Hopkins University Department of Geography and Environmental Engineering, 1976.

Professional Studies/Experience

I am a Research Hydrologist Emeritus with the U.S. Geological Survey (USGS) located at the USGS headquarters in Reston, Virginia. I began my USGS career in 1976 and has conducted research on water supply, water quality, pollutant transport, and flood frequency analysis. My work involved significant involvement in teaching statistical methods to USGS hydrologists (an effort that continues to the present), it also involved development of concept for a National Water Quality Assessment (NAWQA) Program and working within the federal government and with stakeholders to launch that effort.  In 1993-1994 I served as Acting Director of the USGS.  From 1994 through 2008, I served as the Chief Hydrologist of the USGS. In this capacity, I was responsible for all USGS water science programs. These programs encompass research and monitoring of the nation’s ground water and surface water resources including issues of water quantity and quality.  In 2008 I returned to a research position and since that time I have focused efforts on describing long-term changes in streamflow and river water quality.  This includes exploring century-scale trends in flooding nationwide.  It also includes the development and applications of new methods for characterizing trends in river water quality in many regions of the US.  I have published applications of these methods to issues including nutrients and salinity in the watersheds of Chesapeake Bay, Lake Erie, Lake Champlain, and the Mississippi River. This research has provided important insights on causes of the observed trends and has also resulted in the development of software (the EGRET R-Package “Exploration and Graphics for RivEr Trends”) to help scientists analyze long-term water quality and quantity records.  I retired from the USGS in 2018 but continue to collaborate with colleagues inside and outside the USGS as a scientist emeritus.


Professional societies/affiliations/committees/editorial boards

I have served on three different study committees of the Water Science and Technology Board of the National Academies of Science, Engineering and Medicine.  I am currently serving as a member of the Water Science and Technology Board.  I also served for 8 years on the Science and Technical Advisory Committee (STAC) of the Chesapeake Bay Program.