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<br />WATER QUALITY
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<br />Area of ongoing
<br />mapping
<br />oGolden oDenver
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<br />PRODUCTS
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<br />EXPLANATION
<br />NITRATE CON-
<br />CENTRATION
<br />AS NO). IN
<br />MILLlGRAMS
<br />PER LITER
<br />010.0--19.9
<br />e20.0--29.9
<br />.30.0-49.9
<br />.50.0-70.0
<br />
<br />A comprehensive review of exist-
<br />ing water-quality analyses is being con-
<br />ducted to define the chemical quality of
<br />the shallow ground water in the area of
<br />ongoing mapping, The work expands
<br />on that of previous studies (Dennehy
<br />and others, 1995; Shelton and Rogers,
<br />1987), which have indicated that land
<br />use, depth to water table, and rate and
<br />direction of ground-water movement all
<br />can affect shallow grouud-water quality,
<br />Potential constituents and sources of
<br />contamination to the shallow aquifer
<br />include heavy metals from urban and
<br />industrial areas, and nitrates (fig, 5),
<br />ammonia, phosphorus, manganese, and
<br />pesticides from urban and agricultural
<br />sources, A water-quality data base is
<br />planned,
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<br />REFERENCES
<br />
<br />Products of the water activities
<br />in the Front Range Infrastructure
<br />Resources Project will consist of
<br />published reports, geospatial data
<br />available through the U,S. Geological
<br />Survey web sites, and data layers for
<br />use in a project decision-support system,
<br />Two reports are in print (Robson, 1996;
<br />Robson and others, 1998), and others are
<br />planned, Geospatial data from the two
<br />published reports are available through
<br />the U,S, Geological Survey project web
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<br />· 0 1 2 3MILES
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<br />o 1 2 3 KILOMETERS
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<br />Figure 5. Nitrate concentrations in the
<br />shallow aquifer vary from site to site
<br />because the aquifer is easily recharged
<br />and some land use produces high nitrate
<br />recharge (Shelton and Rogers, 1987),
<br />
<br />site at http://webserver.cr.usgs.gov/frirp/.
<br />Additional geospatial data will be
<br />released as reports and meta data
<br />are completed. Data layers for the
<br />decision-support system will be similar
<br />to those on the web site, The decision-
<br />support system will enable users to
<br />access project results for all or part of
<br />the demonstration area, to combine or
<br />manipulate various layers of infonna-
<br />tion, and to display the results in a form
<br />they find useful
<br />
<br />
<br />User-designed maps
<br />showing infrastructure
<br />resources information.
<br />
<br />
<br />Dennehy, KF., Litke, D,W, McMahon, P,B"
<br />Heiny, 1.S" and Tate, CM" 1995, Water-
<br />quality assessment of the South Platte
<br />River Basin, Colorado, Nebraska, and
<br />Wyoming-Analysis of available nutrient,
<br />suspended-sediment, and pesticide data,
<br />water years 1980-92: U,S, Geological
<br />Survey Water-Resources Investigations
<br />Report 94-4095, 145 p,
<br />
<br />Hurr, R.T., Schneider, P.A., Jr., and Minges,
<br />DR, 1975, Hydrology of the South Platte
<br />River Valley, northeastern Colorado: Colo-
<br />rado Water Conservation Board, Water
<br />Resources Circular 28, 24 p.
<br />
<br />HUff, R.T., Schneider, P.A., Jr., and others,
<br />1972, Hydrogeologic characteristics of the
<br />valley-fill aquifer in the Brighton reach of
<br />the South Platte River Valley, Colorado:
<br />U.S. Geological Survey Open.File Report,
<br />2 p" 6 plates, scale 1:62,500,
<br />
<br />Robson, S.G" 1996, Geohydrology of the
<br />shallow aquifers in the Denver metropolitan
<br />area, Colorado: U.S, Geological Survey
<br />Hydrologic Investigations Atlas HA-736,
<br />5 sheets, scale 1:50,000,
<br />
<br />Robson, S,G" Van Slyke, George, and
<br />Graham, Glenn, 1998, Structure, outcrop,
<br />and subcrop of the bedrock aquifers along
<br />the western margin of the Denver Basin,
<br />Colorado: U.S, Geological Survey Hydro-
<br />logic Investigations Atlas HA-742,
<br />5 sheets, scale 1:50,000,
<br />
<br />Shelton, D,C., and Rogers, WP" 1987,
<br />Environmental and engineering geology
<br />of the Windsor study area, Larimer and
<br />Weld Counties, Colorado: Colorado Geo-
<br />logical Survey, Environmental Geology 6,
<br />11 sheets,
<br />
<br />Stollar, RL, 1969, Applications of geophysics
<br />in hydrogeology-Boxelder Creek Valley,
<br />Colorado: Fort Collins, Colorado State Uni-
<br />versity, Master's thesis, 140 p.
<br />
<br />-S,G, Robson and J.S, Heiny
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