• Main Stem Integrator Sites:
  The Colorado River near the Colorado-Utah State line is the integrator site for the entire study unit and represents what is exported from the basin. The Gunnison River near Whitewater is the integrator site for the major tributary within the study unit and represents approximately 40 percent of the flow at the State line. Both sites were previously a part of the National Stream Quality Accounting Network (NASQAN). The Gunnison River below the Gunnison Tunnel and the Gunnison River at County Road 32 represent the inflow and outflow from the National Park Service (NPS) Curecanti Recreation Unit. The sites were selected to assist NPS personnel in the management of resources within the recreation area by describing the temporal variation in water-quality conditions. The Gunnison River below the Gunnison Tunnel serves as a baseline site for the lower Gunnison River basin. The Gunnison River at County Road 32 is an integrator site of the upper Gunnison River Basin.

The Dotsero site is just downstream of the mouth of the Eagle River. The Eagle River basin is currently (2001) undergoing rapid urban development to support recreational land use.

Reference Sites The Upper Colorado River Basin is contained within two major physiographic provinces: Southern Rocky Mountains and Colorado Plateau. One reference site was established in each of these provinces. The reference sites provide data on relatively unimpacted water-quality conditions.
	The Colorado River below Baker Gulch site was located within Rocky Mountain National Park, approximately 10 miles north of Grand Lake, Co., and was the reference site for the Southern Rocky Mountains province. The Colorado Plateau reference site was located on Dry Fork, a tributary to Roan creek, 4 miles northwest of De Beque, Co.

• Indicator Sites
  Three water-quality concerns defined by the UCOL Liaison Committee were impacts due
  to urban/recreation, mining, and agriculture. Two indicator sites were selected for each of these land uses.
  
  
  1. Urban/Recreation
     Sites on Gore Creek and East River were selected for indicators of urban/recreation land use. Gore Creek flows through the town of Vail and empties into the Eagle River. The East River drains the Crested Butte area. These sites are within the Southern Rocky Mountains province where most of the concentrated recreational activity occurs. Both of these areas experience extreme increases in population during the ski season. Hydrologically, the ski season is a period when the streams may be least able to assimilate water-quality impacts. Additionally, the first flush of snowmelt from the towns and lower valleys may significantly load streams on the rising limb of the annual hydrograph.

  2. Mining
     Many areas within the Upper Colorado River Basin are impacted from historic metal mining activity. These areas are found throughout the mineral belt of the Southern Rocky Mountain province. The Uncompahgre River and French Gulch sites were selected to represent impacts from mining. Constituents measured at these sites will include trace elements. The French Gulch site, the smaller of the two basins, has generated intense local interest. The Uncompahgre River site represents a larger basin and many different mining activities.

  3. Agriculture
     One of the major interests to the NAWQA program and to the UCOL Liaison Committee is the effects> of agriculture land use on water quality. There are two major agricultural areas in the UCOL Study Unit; the Grand Valley, which lies along the Colorado River near the city of Grand Junction, and the Uncompahgre- Gunnison near the towns of Delta and Montrose. A basic fixed site was selected in each of the agricultural areas. Both of these areas lie within the Colorado Plateau Province. Agricultural land use within the study unit, with the exception of pastures and hay meadows, is mostly located within the Colorado Plateau. There are currently salinity control and selenium investigation projects run by the Colorado District, Bureau of Reclamation, Colorado State University and other agencies in the two major agricultural areas. The Reed Wash site overlies the Mancos Shale, which is a major contributor of salinity and selenium to surface waters. The Dry Creek at Begonia Road site overlies the Dakota Sandstone, which is not a major contributor of salinity or selenium.

• Introduction
  NAWQA intensive fixed sites are a subset of the basic fixed site network. The UCOL Study Unit operated 2 intensive fixed sites during the 1997 water year. The agricultural indicator site Reed Wash near Mack and the Urban/Recreation indicator site Gore Creek near Minturn were the UCOL intensive fixed sites.

• Objectives and Approach
  The primary objective of the intensive fixed sites is to further define the temporal variation of water-quality impacts due to agricultural and urban/recreational land use. Sampling frequency was related to the growing season, resulting in 23 samples for major ions, nutrients, pesticides, and suspended sediment at Reed Wash. At Gore Creek the sampling frequency was increased during the mid-winter through summer recreation period, resulting in 27 samples for major ions, nutrients, and suspended sediment. Specific conductance was continuously monitored at the intensive fixed sites.

• Introduction
  Surface water synoptics were designed to further define the occurrence and distribution of water quality within the UCOL and to relate water quality conditions to specific types of land use.
  
  
• Trace Elements in the Blue River Basin
  A study of trace-elements in bed-sediment, water-column, and suspended sediment was implemented during low flow conditions of October 1995 and high flow conditions of May 1996. Results of the study are presented in:
  Apodaca, L.E., Driver, N.E., and Bails, J.B., 2000, Occurrence, Transport, and Fate of Trace Elements, Blue River Basin, Summit County, Colorado: An Integrated Approach: Environmental Geology v. 39, no. 8, p. 901-913.
  
  
• Water quality conditions of the Slate and East Rivers
  A synoptic to investigate the nutrient and algal characteristics of the Slate and East Rivers during the winter recreational season was designed and implemented in water year 1997. Data were collected at 4 sites on the Slate River and 2 sites on the East River for a 24 hour period during the Christmas-New Year holiday period. Results of this study are presented in:
  Spahr, N.E., and Deacon, J.R., 1998, Water-Quality Characteristics of the Slate and East Rivers, Colorado, During the Winter Recreational Season, December 1996: U.S. Geological Survey Open-File Report 98-279, 9 p.
  
  
• Water quality in agricultural areas of the UCOL
  Water quality samples were collected from 44 streams and agricultural drains in the Grand Valley and Uncompahgre River Valley during May 1998. Samples were analyzed for major ions, nutrients, pesticides, and suspended sediment. Results of the pesticide portion of this synoptic are presented in:
  Bauch, N.J., and Spahr, N.E., 2000, Pesticides in Surface Waters of the Upper Colorado River Basin, Colorado, 1996-98: U.S. Geological Survey Water-Resources Investigations Report 00-4005, 46 p.

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