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<br />consists of streams with steep gradients; cobble and boulder sub-
<br />strate; and cool, clear, forested headwaters traversing crystalline
<br />bedrock at high altitudes that have extended periods of ice and snow
<br />cover. Lower gradient streams of the Colorado Plateau physio-
<br />graphic province consist of sand and silt substrate; sparse vegeta-
<br />tion; and warmer, more saline water that flows through sedimentary
<br />rocks. Distinct biological communities are associated with the
<br />two physiographic provinces, principally because algae, macro-
<br />invertebrates, and fish of the UCaL vary with altitude and physical
<br />habitat. In general, the predominant biological communities in the
<br />Southern Rocky Mountains province consist of green algae and
<br />diatoms; caddisfIies, mayflies, and stoneflies; and cold-water fish
<br />species, including trout. The predominant biological communities
<br />in the Colorado Plateau province consist of blue-green, golden-
<br />brown, and green algal species; aquatic worms, dobsonflies, and
<br />crayfish; and warm-water fish species, including carp, catfish, and
<br />suckers.
<br />
<br />LAND-USE EFFECTS
<br />
<br />Mining activities have severely altered aquatic life and habitat
<br />in many of the headwater reaches of the Colorado River and its
<br />tributaries (Colorado Water Quality Control Division, 1989). As
<br />tributaries with different water chemistry converge and mix, precipi-
<br />tation of metals can occur. This precipitation can directly affect
<br />certain biological communities and habitat by coating the substrate
<br />with toxic constituents. The coating decreases habitat availability
<br />and provides a mechanism for contamination.
<br />
<br />Urbanization in the UCaL study unit has become increasingly
<br />important in its effects on water quality and its associated effects
<br />on biological communities. Development and construction activities
<br />can increase sedimentation, which adversely affects water quality
<br />and, therefore, affects algae, macroinvertebrate, and fish life by
<br />decreasing light, decreasing habitat availability, and having the
<br />potential of increasing contaminant loads in streams.
<br />
<br />Agricultural activities also affect water quality in the study unit.
<br />Nutrients derived from fertilizers can indirectly cause detrimental
<br />effects on'aquatic fauna by overstimulating the growth of various
<br />algal species. Pesticides commonly are used in agricultural areas in
<br />the study unit and can cause damaging effects on the biota because
<br />of acute or chronic toxic exposure. Studies conducted on the water
<br />quality of irrigation return flows in the study unit have indicated
<br />adverse effects on biota from pesticides and selenium, a naturally
<br />occurring element in the soil.
<br />
<br />SAMPLING DESIGN
<br />
<br />The biological component of the NA WQA program consists of
<br />characterizing algal, macroinvertebrate, and fish communities and
<br />habitat at each surface-water sampling site and analyzing fish tissue
<br />and bed sediment for trace-element and organic contaminants. The
<br />resulting information can be integrated with physical and water-
<br />chemistry data to provide multiple lines of evidence for the assess-
<br />ment of water quality in the UCaL study unit. A more detailed
<br />description of surface-water sampling sites in the study unit is in
<br />Spahr and others (1996).
<br />
<br />The sampling design for the biological component in the UCaL
<br />study unit is enhanced by the inventory of existing biological and
<br />contaminant information. This information also can be useful in the
<br />selection of sampling sites for future studies and for avoidance of
<br />duplicative studies. Identified gaps in the biological data can be
<br />addressed to meet national needs of the NA WQA program and local
<br />needs in the study unit. The biological inventory can be used to
<br />select biological sampling sites; design sampling strategies; and
<br />integrate physical, chemical, and biological information for the
<br />UCaL study unit.
<br />
<br />April 1997
<br />
<br />UPPER COLORADO RIVER '. 106n
<br />BASIN STUDY UNIT l:''..._,~.1... '"
<br />~COLORADO ~ J'
<br />~ 10?:.J.,! _~"~ .J
<br />400-;;("""
<br />
<br />~080 \ ~.,~t.I..., <%. \ )
<br />o ".,--......... ""rlJ.. cagte "%
<br />1 09 '. J . . ...... ..... GI!!,nw:>-,_..- ....~~ ~".
<br />( Colo,ada \? \.4.-
<br />... \ ~.. ,,--~
<br />\ _".. ...J
<br />I .~~ jSOUTHERN
<br />"'.\>~ROCKY
<br />" - MOUNTAINS
<br />
<br />I ) ,
<br />f ... I
<br />I ~
<br />I \
<br />;1 ._ Ounl'uaon ':...
<br />-------
<br />COLORAD~...... '~r;
<br />PLATEAU "'-1'"1 '< I .
<br />'<..;J/i. . 0 20
<br />380'~ C I I I I
<br />~ f\ ,,...~ 0 20 40 KILOMETERS
<br />EXPLANATION ....... ~
<br />
<br />
<br />40 MILES
<br />I
<br />
<br />...
<br />
<br />Physiographic province boundary
<br />Study unit boundary
<br />Biological sampling sites
<br />
<br />Location of Upper Colorado River Basin study unit. physiographic
<br />provinces, and biological sampling sites.
<br />
<br />REFERENCES CITED
<br />
<br />Apodaca, L.E., Driver, N.E., Stephens, V.c., and Spahr, N.E.,
<br />1996, Environmental setting and implications on water
<br />quality, Upper Colorado River Basin, Colorado and Utah:
<br />U.S. Geological Survey Water-Resources Investigations
<br />Report 95-4263, 33 p.
<br />Colorado Water Quality Control Division, 1989, Colorado nonpoint
<br />assessment report-l 989 addendum: Denver, Colorado
<br />Department of Health, 189 p.
<br />Deacon, J .R., and Stephens, V.c., 1996, Summary of biological and
<br />contaminant investigations related to stream water quality
<br />and environmental setting in the Upper Colorado River Basin,
<br />1938-95: U.S. Geological Survey Water-Resources Investiga-
<br />tions Report 96-4172, 37 p.
<br />Gurtz, M.E., 1994, Design of biological components of the National
<br />Water-Quality Assessment (NA WQA) program, chap. 15 of
<br />Loeb, S.L., and Spacie, Anne, eds., Biological monitoring
<br />of aquatic systems: Boca Raton, Fla., Lewis Publishers,
<br />p. 323-354.
<br />Spahr, N.E., Driver, N.E., and Stephens, V.c., 1996, The Upper
<br />Colorado River National Water-Quality Assessment program
<br />surface-water-monitoring network: U.S. Geological Survey
<br />Fact Sheet 191-96,4 p.
<br />
<br />Information on technical reports and hydrologic data related to the
<br />NA WQA program can be obtained from:
<br />
<br />Upper Colorado River Basin NA WQA Manager
<br />U.S. Geological Survey
<br />Denver Federal Center
<br />Mail Stop 415, Box 25046
<br />Lakewood, ca 80225
<br />(303) 236-2101 ext. 224
<br />
<br />email: nedriver@usgs.gov
<br />
<br />
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