|
the status and trends in the quality of the Nation's
<br />surface- and ground-water resources and to provide an
<br />understanding of the natural and human factors that
<br />can affect the quality of these resources (Leahy and
<br />others, 1990). The program, which consists of 60
<br />study units, is interdisciplinary and integrates
<br />chemical, physical, and biological data to assess the
<br />Nation's water quality at local, regional, and national
<br />levels (Meador and Gurtz, 1994). In 1991, the USGS
<br />began full implementation of the NAWQA program.
<br />The Upper Colorado River Basin (UCOL) study unit
<br />was in the second group of 20 NAWQA study units
<br />selected in 1994 for implementation of the program.
<br />The overall goals of the NAWQA program are to
<br />(1) provide a nationally consistent description of
<br />current water-quality conditions for a large part of the
<br />Nation's water resources; (2) define long-term trends
<br />in water quality; and (3) identify, describe, and
<br />explain, to the extent possible, the major factors that
<br />affect water-quality conditions and trends.
<br />The program focuses on a broad spectrum of
<br />constituents ar..d sampling approaches for surface
<br />water, including information on (1) biological investi-
<br />gations (algae, macroinvertebrate, and fish communi-
<br />ties); (2) stream habitat characterization (Gurtz, 1994);
<br />and (3) trace-element and organic contaminants in
<br />organism tissue and bed sediment. This information is
<br />integrated, as much as possible, with the surface-
<br />water-quality data that include discharge, specific
<br />conductance, temperature, pH, dissolved oxygen and
<br />concentrations of suspended sediment, inorganic
<br />constituents (major ions, nutrients, and trace
<br />elements), radionuclides, and organic contaminants in
<br />water.
<br />The ecology of biological communities and
<br />contaminants in organism tissue and in bed sediment
<br />are two biological components used in the NAWQA
<br />program to provide multiple lines of evidence
<br />(chemical, physical, and biological) for the assessment
<br />of water quality. By linking the various components
<br />of water quality at various spatial scales, the NAWQA
<br />program can provide the kinds of information needed
<br />to generate policies and management actions that
<br />improve the Nation's water resources (Meador and
<br />Gurtz, 1994). The resulting information then can be
<br />used to design biological sampling strategies to fill in
<br />gaps in the biological and contaminant data and to
<br />effectively address critical water-quality issues in the
<br />UCOL study unit.
<br />Biological components are useful indicators of
<br />water quality because biota respond to a variety of
<br />natural and human environmental effects, including
<br />stresses from point and nonpoint sources, toxic
<br />effluents, enriched organic effluents, extreme flows,
<br />and habitat degradation. Biota also provide spatial
<br />and temporal information and, in many studies, are
<br />more sensitive indicators of environmental change
<br />than are other media (Gurtz, 1994). Biological
<br />communities, including algae, macroinvertebrate, and
<br />fish communities; habitat characterization; and
<br />contaminants in organism tissue and in bed sediment
<br />are factors assessed by the UCOL study unit. The first
<br />step in the implementation of the biological
<br />component of the NAWQA program for the UCOL
<br />study unit is an inventory of existing biological and
<br />contaminant information.
<br />Purpose and Scope
<br />This report (1) identifies sources of biological
<br />and contaminant information in the UCOL study
<br />unit; (2} broadly summarizes existing information
<br />about biological and contaminant investigations;
<br />(3) discusses gaps in biological and contaminant
<br />information for the basin; and (4) categorizes this
<br />information according to the environmental setting.
<br />The data source for this report was a subset of
<br />references compiled from a computerized biblio-
<br />graphic search of 21 data bases (Bauch and Apodaca,
<br />1995). Additional information was provided by
<br />several Federal and State agencies, including the
<br />U.S. Fish and Wildlife Service, U.S. Environmental
<br />Protection Agency, National Park Service, Bureau of
<br />Reclamation, Colorado Division of Wildlife, Colorado
<br />Water Resources Research Institute; and by local
<br />universities.
<br />Description of Study Unit
<br />The UCOL study unit has varied climate,
<br />geology, topography, and hydrology. The study unit
<br />has a drainage area of about 17,800 mil. The primary
<br />river in the study unit, the Colorado River, originates
<br />in the mountains of central Colorado and flows about
<br />230 mi southwest into Utah (fig. 1). The headwaters
<br />of the Colorado River and most of its tributaries
<br />originate in the mountains that form the eastern and
<br />Summary of Biological and Contaminant Investigations Related to Stream Water Quality and Environmental Setting In the
<br />Upper Colorado River Basin, 1938 95
<br />
|