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

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15

characterized by large spring peaks and low base flow.
Typically, spring runoff began in March, peaked in mid-May to
early June and ended by the first week of July. Flow the
remainder of the year was characteristically low, punctuated by
large, short duration peaks caused by summer and fall storm
events.

Since the completion of Navajo Dam in 1962, flows below Navajo
Reservoir have been largely controlled and stabilized. Spring
peak flows have been significantly reduced in magnitude, base
flows have been increased and stabilized, and late winter flows
have increased markedly to provide storage space in the reservoir
for the spring runoff. In addition to moderating natural flows,
hypolimnetic releases from Navajo Reservoir have decreased mean
annual water temperature and diminished temperature fluctuations
of the San Juan River downstream to near the confluence of the
Animas River.

From Navajo Dam to Lake Powell, the river is supplemented by
perennial and ephemeral tributary streams, arroyos, and washes,
and diverted for use by industry, municipalities, and
agricultural irrigation. The inflows below Navajo Dam provide
the main variation in flow, including thunderstorm peaks and a
typically shaped but reduced magnitude spring runoff.

2.2.2 Development and Depletions

There are many points of water diversion, including a number of
pumps on the San Juan River between Navajo Dam and its confluence
with Lake Powell. Downstream of the dam, water is diverted for
the Hammond Canal, Farmers Mutual Ditch, Fruitland Irrigation
Canal, San Juan Power Plant, Jewett Valley Ditch, Four Corners
Power Plant, Hogback Canal, Cudei Ditch, and a few lesser water
users. A portion of the diversion for the Four Corners Power
Plant is returned to the San Juan River via Chaco Wash.
Additional return flows enter the San Juan River from irrigation
and municipal diversions, the Animas River, the La plata River,
the Mancos River, McElmo Creek, and Montezuma Creek. Irrigation-
return flow from Dolores River diversions enters the San Juan
River via Mancos River and McElmo Creek, augmenting the natural
flows of the San Juan River.

There are six diversion structures in New Mexico on the mainstem
San Juan River, five of which are downstream of Farmington. Each
is a potential impediment to fish movement, particularly during
low flow periods. The diversion structures range from soil and
boulder dikes to concrete and metal weirs over which the entire
river flows. The most upstream of these obstructions is a levee
at the head of the Hammond Canal, upstream of the confluence with
the Animas River. The second is located just above the
confluence of the San Juan and La Plata rivers that diverts water
into Fruitland Irrigation Ditch. The San Juan Power Plant