7370

• UCREFRP Catalog Number: 7370
• Author: Platania, S. P.
• Title: Biological Summary of the 1987 to 1989 New Mexico-Utah Ichthyofaunal Study of the San Juan River.
• USFW Year: 1990.
• USFW - Doc Type: Albuquerque, New Mexico.
• Copyright Material: NO

1987 to 1989'Study Area
while the scope of this report required the inclusion of
data from throughout the San Juan River Sub-basin, the emphasis
of the 1987 to 1989 study was the 198 mile (319 km) reach between
Farmington, New Mexico and Piute Farms Marina, Utah (Figure -6).
The New Mexico portion of the study area was the section of
the San Juan River from Farmington, New Mexico (RM 198)
downstream to the U.S. Highway 160-Bridge (RM 136) in Montezuma
County, Colorado, a reach of about 100 km (62 mi). The Utah
portion of the study area was the San Juan River from the U.S.
Highway 160 Bridge (RM 136) in Colorado downstream to Piute Farms
Marina (RM 0) on Lake Powell, Utah.
New Mexico: RM 198 to RM 136
In New Mexico, the San Juan River bisects a large,
relatively low-relief intermontane plateau composed primarily•of
Mesozoic and Cenozoic strata. River elevation was 1,609 m (5,279
ft) at Farmington (RM 198), 1,524 m (5,000 ft) at the geologic
formation known as the Hogback (RM 177), 1,478 m (4,849 ft) at
Shiprock (RM 166), and 1,423 m (4,669 ft) at the U.S. Highway 160
Bridge (RM 136) near Four Corners. Average gradient from
Farmington to the Hogback was 2.5 m/km (13.2 ft/mi) and 1.7 m/km
(9.0 ft/mi) from the Hogback to Four Corners. The river was
generally restricted to a single channel between Farmington and
Shiprock, but was often braided between Shiprock and Four
Corners.
Upland vegetation in the vicinity of the river was composed
primarily of grama (Bouteloua spp.) and galleta (Hilaria spp.)
(Morain et al. 1977). Riparian vegetation consisted mainly of
introduced salt cedar (Tamarix chinensis) and Russian olive
(Eleagnus angustifolia) and native cottonwood (Populus fremontii)
and willows (Salix spp). Below Shiprock, cottonwoods and willows
were scarce and the banks were lined with dense stands of salt
cedar and Russian olive.
The floodplain from Farmington to Shiprock was largely
privately owned and was modified for agriculture. Uplands to the
north are mixed federal, state, and private land while that south
of the river was part of the Navajo Indian Reservation. From
Shiprock to Four Corners, the floodplain and uplands are
completely within the Navajo Indian Reservation and grazing was
the primary land use.
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