WSPC12741

• File Number: 8064.200.A
• Description: Indian Water Rights - Gallup-Navajo
• Date: 9/3/2004
• Author: USDOI/BOR
• Title: Biological Assessment, Navajo Gallup Water Supply Project - Report and Appendices
• Water Supply Pro - Doc Type: Publication

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5.3 Fish

The San Juan River has been the subject of intensive recovery efforts on behalf of the
endangered Colorado pikeminnow and razorback sucker. To facilitate coordination among
studies, the river has been divided into study reaches. These reaches are presented in Figure 5.1
and are referred to in discussions of each species that occurs in the San Juan River.

5.3.1 Zuni Bluehead Sucker (Catostomus discobolus varrow/)

The Zuni bluehead sucker is a subspecies of the bluehead sucker historically found in the
headwaters of the Linle Colorado River. It is a candidate for protection under the ESA and an
NESL Group 4 species. This subspecies is not known to occur in the San Juan River, and would
not be affected by project water withdrawals.

5.3.2 Colorado Pikeminnow (Ptvchocheilus lucius)
The Colorado pikeminnow is protected as endangered under the ESA and NESA.

This large (up to 6 ft and 100 lbs), piscivorous fish is the largest member of the minnow family.
Adult fish inhabit large to medium rivers and are found in turbid, deep pools with a strong
current and rocky or sandy substrate. Juvenile fish use backwater and side channel habitats with
silt or sand substrates and consume insects and crustaceans (NMGFD 2000). Pikeminnows
spa'\\'n from early July through mid August. Preferred spawning sites are riffles with gravel to
cobble substrates (Lamara et al. 1985). The Colorado pikeminnow is endemic to the Colorado
River basin and historically inhabited the main river channels. It is now found in small numbers
only in limited ponions of the upper Colorado basin in Colorado, Utah and New Mexico,
occupying about 25 percent of its former range. Within the San Juan River the Colorado
pikeminnow has been collected from RM 0 to RM 177.1 (Ryden 2oooa; Ryden 2ooob).

Critical habitat has been designated for this species from ~eskahai Canyon in Lake Powell
(approximate low water confluence with the San Juan River) to the confluence of the Animas
and San Juan Rivers at RM 180.

Mark recapture estimates place 19 wild adult Colorado pikeminnow in the San Juan River from
Ry! 136.6 to &"1 119.2 (95% c.!. 10-42; Ryden 2000a). Radio tagged adults appear to have
relatively small home ranges and primarily use habitats from RM 109 to RM 142. The exception
to this trend was one fish that consistently used habitats immediately downstream of Bluff, UT
(Ryl 80; Ryden 2000a). Spawning has been documented in a region of high channel complexity
characterized by shifting gravel bars from &\1 133.4 to RM 129.8 (Ryden 2000a). Additional
suitable spawning habitat has been identified at RM 178.7 and 168.4 (Bliesner 2003). Drift data
from 1995 suggested a spawning site considerably downstream ofRM 129 (platania, et al. 2000)
but its location was not identified. Prior to spawning, adults stage at the mouth of the Mancos
River. Spawning dates (back calculated from larval drift) range from July 8 to August 12
(Platania et al. 2000). Larval and juvenile pikeminnow have been collected from low velocity
shoreline and pocketwater habitats downstream of &"1130 (Ryden 2oooa).

BIOLOGICAL ASSESSMENT
NAVAJO GALLUP WATER SUPPLY PROJECT
September 3. 2004

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