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6 Water-Quality Characteristics and Ground-Water Quantity of the Fraser River Watershed, Grand County, Colorado, 1998-2001
<br />of the USGS in collecting the surface-water-quality data.
<br />Thanks also are extended to Lori Apodaca and Daniele Chafin
<br />for technical review of the manuscript, Mary Kidd for editorial
<br />review, Sharon Powers for illustrations, John Evans for cover
<br />design, and Alene Brogan for manuscript preparation and lay-
<br />out.
<br />Data Collection and Analysis
<br />at well 3 was discontinued after 1999 because it represented a
<br />ground-water resource that was sufficiently represented by
<br />other wells in the same area. Wells were located in fractured
<br />granite (one well), in the sedimentary Troublesome Formation
<br />(four wells), and in alluvium (six wells) and ranged in depth
<br />from 18 to 295 ft. The single surface-water site (site 12, Fraser
<br />River below Crooked Creek at Tabernash) was selected to rep-
<br />resent the integration of the effects of natural and human factors
<br />on surface-water quality in the Fraser River watershed upstream
<br />from Tabernash.
<br />Water-quality data were collected from August 1998
<br />through September 2001 at 1 1 ground-water sites, including
<br />2 sites that were sampled for only a portion of the study, and
<br />1 surface-water site (fig. 1, table 1). The 1 I ground-water sites
<br />were selected to represent different aquifers, different land-use
<br />settings, and varying depths to ground water within the Fraser
<br />River watershed. Well selection was based on well availability,
<br />location in areas with historical or new ISDS use or non-ISDS
<br />use, and areal distribution throughout the study area. Well 1,
<br />currently in a nonurban and non-ISDS area, was added to the
<br />sample-collection network in 2000 upon the request of the
<br />cooperator, the Grand County Board of County Commissioners,
<br />because of impending development in the area. Data collection
<br />Ground-water quantity was evaluated for the surficial allu-
<br />vial aquifer and the Troublesome Formation aquifer. The areal
<br />extent of the aquifers was derived from geologic maps of
<br />Colorado (Green, 1992; Tweto, 1979). Information on aquifer
<br />thickness was gathered from lithologic well logs obtained at the
<br />Colorado Division of Water Resources. Aquifer properties were
<br />derived from available aquifer-test information as well as com-
<br />parison to similar aquifer systems. A more detailed discussion
<br />of the estimation of ground-water quantity, or the amount of
<br />water available to be withdrawn by wells, in the alluvial and
<br />Troublesome Formation aquifers can be found in the "Ground-
<br />Water Quantity" section of this report.
<br />Table 1. Description of 11 ground-water wells and one surface-water sampling site in the Fraser River watershed,
<br />August 1998-September 2001.
<br />[USGS, U.S. Geological Survey: ft, feet, ISDS, individual septic disposal system; CFC, chlorotluorocarbon; M. monitoring; Muni, municipal; D, domestic; Fm.
<br />Formation; NU, nonurban; U, urban]
<br />
<br />Site
<br />number
<br />
<br />(fig. 1)
<br />
<br />USGS station
<br />number
<br />Alti-
<br />tude
<br />
<br />(ft)
<br />
<br />Well
<br />type
<br />
<br />Aquifer Well
<br />depth
<br />below
<br />land
<br />surface
<br />(ft)
<br />
<br />Land
<br />use
<br />Loca-
<br />tion in
<br />ISDS
<br />area
<br />CFC esti-
<br />mated
<br />recharge
<br />date2
<br />Data-
<br />collection
<br />period for
<br />well
<br /> Ground-water-quality wells
<br />1 395623105481000 8,619 M Alluvial 18 NU No 31989 2000-01
<br />2 395658105485400 8,568 Muni Troublesome Fin 110 U No 1983 or 1998-2001
<br /> Younger
<br />3 395642105500700 8,685 D Troublesome Fm 145 U Yes 1968 1998-99
<br />4 395657105495300 8,610 D Alluvial 85 U Yes 1980 1998-2001
<br />5 395750105515800 8,665 D Troublesome Fm 120 NU Yes 1979 1998-2001
<br />6 395921105472300 8,531 D Alluvial 75 NU No 1991 1998-2001
<br />7 395942105502000 8,332 D Alluvial 65 U Yes 1969 or 1998-2001
<br /> younger
<br />8 395937105500500 8,342 D Alluvial 25 U Yes 1990's 1998-2001
<br />9 395929105510300 8,320 M Alluvial 28 U No 1976 1998-2001
<br />10 395928105533500 8,592 D Troublesome Fm 295 NU No 1968 1998-2001
<br />11 395907105540100 8,582 D Precambrian granite 105 NU No 1955 1998-2001
<br /> Surface-water-quality site
<br />12 09033300 8,270 Station name: Fraser River belo w Crooked Creek at Tabernash, Colorado
<br />From Tweto (1979) and Green (1992).
<br />'From Apodaca and others (2000), unless otherwise noted
<br />`From Apodaca and others (2002).
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