WSPC02454

• File Number: 8283.200
• Description: Colorado River Basin-Colorado River Computer Models-Colorado River Decision Support System
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 12/1/1995
• Title: San Juan River Basin Modeling-San Juan Special Water Right Operations
• Water Supply Pro - Doc Type: Report/Study

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SAN JUAN-CHAMA PROJECT

The San Juan-Chama Project was developed by the U.S. Bureau of Reclamation (USBR) as
a participating project of the Colorado River Storage Project (CRSP). The project diverts water
from tributaries of the San Juan River in the Colorado River basin for delivery to the Rio Grande
basin. The water is used for municipal, domestic and industrial purposes in central New Mexico
and also provides a supplemental irrigation supply to approximately 92,500 acres. The San Juan-
Chama Project was designed to yield an average of about 110,000 acre-feet per year.

There are three principal diversion facilities on tributary streams in Colorado's Irrigation
Division 7. The Blanco Diversion Dam (WOlD 294667) diverts from Rio Blanco and delivers the
water into the Blanco Tunnel. The Blanco Tunnel, with a design capacity of 520 cfs, carries the
water 8.64 miles from Rio Blanco to the Little Navajo River. The Little Oso Siphon carries the
water under Little Navajo River and into the Oso Tunnel. Additional water from the Little Navajo
is diverted at the Little Oso Diversion Dam IWDID 774636) and is added to the flow of the Oso
Tunnel.

The Oso Tunnel, with a capacity of 550 cfs, carries the water 5.05 miles from the Little
Navajo River to the Navajo River. The Oso Siphon carries the water under the channel of the
Navajo River and into the Azotea Tunnel. Additional water from the Navajo River is diverted at
the Oso Diversion Dam (WOlD 774635) and is added to the flow through the Azotea Tunnel. The
Azotea Tunnel, with a capacity of 950 cfs, carries the water 12.8 miles from the Navajo River to
Azotea Creek in the Rio Grande basin.

The cumulative diversions at the three diversion dams represent an ~ from the
Colorado River basin. There are no return flows to the San Juan River drainage. Records of the
monthly diversions at the three diversion structures were obtained from the USBR for Water Years
1971 through 1993. The average annual diversions for this 23-year period are shown below:

Rio Blanco (WDID 294667)
Little Navajo (WDID 774636)
Navajo River IWDID 774635)
TOTAL

38,880 ACFT
4,370 ACFT
46.030 ACFT
89,280 ACFT

The authorizing legislation for the San Juan-Chama Project places additional limitations on
the diversions from the Colorado (San Juan) River basin. Diversions cannot exceed 1,350,000
acre-feet in any period of ten consecutive years and cannot exceed 270,000 acre,feet in anyone
year. Diversions by the Project are also subject to minimum bypass requirements at each of the
diversion structures. These bypass requirements (cfs) are set forth below:

MONTH RIO BLANCO LITTLE NAVAJO NAVAJO RIVER
January 15 4 30
February 15 4 34
March 20 4 37
April 20 4 37
May 40 27 88
June 20 27 55
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