WSP11103

• File Number: 8240.300.10
• Description: San Juan Recovery Implementation Program
• Basin: San Juan/Dolores
• Date: 2/1/1995
• Author: SJRIP
• Title: San Juan River Basin Recovery Implementation Program - Program Document
• Water Supply Pro - Doc Type: Publication

I
I
I
I
t
I
,
I
I
t
I
I
I
I
I.
I
I
I
I

3

1.3 BIOLOGICAL BASIS FOR THE RECOVERY PROGRAM

1.3.1 Water development

The San Juan River is a major tributary of the Colorado River
Basin. In 1922, the seven basin states of Utah, Colorado,
Wyoming, New Mexico, Arizona, Nevada, and California signed a
compact dividing the Colorado River between the Upper and Lower
Colorado River basins. In 1948, the Upper Basin states (Wyoming,
Colorado, Utah, and New Mexico), together with Arizona, signed an
agreement apportioning the upper basin share between the states.
Arizona was apportioned 50,000 acre-feet in that agreement. Each
of the States and the Bureau of Reclamation under the authority
of the Colorado River Storage Project Act (CRSP), initiated the
development of the waters of the Upper Colorado River basin. The
passage of the CRSP Act allowed for the construction of many
large mainstem impoundments on the Colorado River and various
tributaries including Navajo Dam on the San Juan, Flaming Gorge
on the Green River and the Aspinall Unit on the Gunnison River.

While the construction of these impoundments was essential for
the development of water storage and flood control and to allow
the Upper Basin States to develop their water resources, their
construction and operation altered natural river ecosystems and,
thereby, the native floral and faunal communities of the Colorado
River. As a result, natural riverine habitats were altered,
migration routes were blocked, and selective chemical treatments
were applied to eradicate native species in favor of non-native
sport fish species.

The physical and biological changes to the environment, such as
the disruption of the natural flow regime and changes in water
temperature and quality, that were brought about by the
construction of these large mainstem impoundments, led to the
endangerment of four native fish species of the Colorado River.
Two of these species, Colorado squawfish and razorback sucker,
inhabit the San Juan River; a third, bony tail, probably occupied
the river; and the fourth, humpback chub, may have historically
occurred in the river.

1.3.2 Other Human Induced Impacts

Other human-induced impacts to the Colorado River System and
specifically to the San Juan River include contamination from oil
and gas development and agricultural return flows which may
contain heavy metals and other forms of contamination. Urban
development in the Basin, with attendant urban runoff, sewage
effluent, and watershed alterations have also affected the
aquatic environments of the San Juan River drainage.

The cumulative effects of these and other possible impacts have
resulted in reduced population levels of the native fish species,