GAGES-II: Geospatial Attributes of Gages for Evaluating Streamflow

This dataset, termed "GAGES II", an acronym for Geospatial Attributes of Gages for 
Evaluating Streamflow, version II, provides geospatial data and classifications for 9,322 
stream gages maintained by the U.S. Geological Survey (USGS). It is an update to the 
original GAGES, which was published as a Data Paper on the journal Ecology's website 
(Falcone and others, 2010b) in 2010. The GAGES II dataset consists of gages which 
have had either 20+ complete years (not necessarily continuous) of discharge record 
since 1950, or are currently active, as of water year 2009, and whose watersheds lie 
within the United States, including Alaska, Hawaii, and Puerto Rico. Reference gages 
were identified based on indicators that they were the least-disturbed watersheds within 
the framework of broad regions, based on 12 major ecoregions across the United States. 
Of the 9,322 total sites, 2,057 are classified as reference, and 7,265 as non-reference. 
Of the 2,057 reference sites, 1,633 have (through 2009) 20+ years of record since 1950. 
Some sites have very long flow records: a number of gages have been in continuous 
service since 1900 (at least), and have 110 years of complete record (1900-2009) to date.
			  
The geospatial data include several hundred watershed characteristics compiled from 
national data sources, including environmental features (e.g. climate – including historical 
precipitation, geology, soils, topography) and anthropogenic influences (e.g. land use, 
road density, presence of dams, canals, or power plants). The dataset also includes 
comments from local USGS Water Science Centers, based on Annual Data Reports, 
pertinent to hydrologic modifications and influences. The data posted also include 
watershed boundaries in GIS format. 
			  
This overall dataset is different in nature to the USGS Hydro-Climatic Data Network 
(HCDN; Slack and Landwehr 1992), whose data evaluation ended with water year 1988. 
The HCDN identifies stream gages which at some point in their history had periods which 
represented natural flow, and the years in which those natural flows occurred were identified 
(i.e. not all HCDN sites were in reference condition even in 1988, for example, 02353500). 
The HCDN remains a valuable indication of historic natural streamflow data. However, the 
goal of this dataset was to identify watersheds which currently have near-natural flow 
conditions, and the 2,057 reference sites identified here were derived independently of the 
HCDN. A subset, however, noted in the BasinID worksheet as “HCDN-2009”, has been 
identified as an updated list of 743 sites for potential hydro-climatic study. The HCDN-2009 
sites fulfill all of the following criteria: 
	(a) have 20 years of complete and continuous flow record in the last 20 years 
(water years 1990-2009), and were thus also currently active as of 2009, 
	(b) are identified as being in current reference condition according to the GAGES-II classification, 
	(c) have less than 5 percent imperviousness as measured from the NLCD 2006, and 
	(d) were not eliminated by a review from participating state Water Science Center evaluators.
			  
The data posted here consist of the following items:- This point shapefile, with summary data 
for the 9,322 gages.- A zip file containing basin characteristics, variable definitions, and a more 
detailed report.- A zip file containing shapefiles of basin boundaries, organized by classification 
and aggregated ecoregion.- A zip file containing mainstem stream lines (Arc line coverages) for 
each gage.

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Organization: Department of the Interior