9326

• UCREFRP Catalog Number: 9326
• Author: U.S. Fish and Wildlife Service.
• Title: Draft Biological Opinion for Ute Water/Plateau Creek Pipeline Replacement Project, Mesa County, Colorado.
• USFW Year: 1996.
• USFW - Doc Type: Denver.
• Copyright Material: NO

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potentially habitable by endangered fishes for use in spawning, nursery,
feeding, and rearing or corridors between these areas. Biological environment
includes food supply, predation, and competition.
Water Ouantitv h~,'l~2 Z i.
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The environmental baseline for the Pro' ct includes all historical depletions
in the Upper Colorado River Basin, de etions resulting from projects which
have previousl under one sec 7 onsultation, and depletions resulting
from projects contemporaneous with this consu tation. The projects included
in the baseline and their associated depletions are listed in the Biological
Assessment, Appendix B, Table 3.8.
The baseline for water quantity calculated as average monthly flows for each
month of the period of record is incorporated in the hydrological analysis
tables in the Biological Assessment, Appendix 6, Attachment E, Column 3.2,
labeled "Adjusted Historic Flow At Top Of Reach". This baseline is also
represented in the figures in Attachment F where it is labeled "Adjusted
Historic Flow".
Water Ouality
Water depletions, by reducing dilution effects, have increased the
concentrations of heavy metals, selenium, salts, PAHs, pesticides, and other
contaminants in the Colorado River. Selenium is of particular concern because
of its documented effects on fish (and wildlife) reproduction. Recent United
States Geological Survey data collected in the Colorado River from 1990 to
1996 show that selenium concentrations under existing conditions (current
level of development, not section 7 baseline) have been as high as 2 ug/L in
the 15-mile reach and as high as 6 ug/L below the 15-mile reach. In 1995,
Colorado's Water Quality Control Commission reduced the chronic selenium
standard from 17 ug/L to 5 ug/L,~ The Service recommended the level be lowered
to 2 ug/L. ~ .
Physical Habitat ~ 5~~.
Water depletions, by affecting the quantity and timing of flows, have reduced
the ability of the river to create and maintain habitats and have reduced the
frequency and duration of availability of certain habitats.
Habitat Formation
The formation of a variety of channel habitats, including gravel/cobble bars
and substrates used by Colorado squawfish for spawning, is essential to ensure
the availability of the range of habitats required by all endangered fish life
stages to fulfill daily requirements (foraging, resting, spawning, avoiding
predation, etc.) under various flow conditions. The number and distribution
of these channel habitats can be described as channel habitat complexity,
diversity, or heterogeneity. Osmundson and Kaeding (1991) found that adult
Colorado squawfish in the Grand Valley prefer river segments with a complex
morphometry over those that are simple.