WSP07035

• File Number: 8509
• Description: San Luis Valley
• State: CO
• Basin: Rio Grande
• Water Division: 3
• Date: 12/1/1969
• Title: Irrigation Water Management Study of the San Luis Valley Colorado - PART 1 of 2
• Water Supply Pro - Doc Type: Report/Study

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Since then recharge by canal leakage, applied irrigation water,
and uncontrolled fla.v fran artesian wells has filled the
valley fill of the Rio Grande fan to within 5 to 20 feet
of the land surface.

The unconfined a<:X1Uifer underlying the Rio Grande fan helps
to regulate the water supply in the closed basin. Ground
water withdrawn during periods of la.v surface-water supply
is replenished during periods of abundant supply....

The settlement at San Iuis (the oldest t= in Colorado) led to
the construction of ditches and the oldest court decree (April 10,
1852) for irrigation in Colorado. By 1900 sare 1,800 miles of
canals and ditches had been constructed. 'Ihe average annual
delivery of irrigation water in the San Luis Valley, Colorado,
is about 1 million acre-feet to about 600,000 acres of land.
Developrrent since 1900 has largely been confined to inprovements
in existing systems and installation of many irrigation wells -
both artesian and purrped.

THE RIO GRANDE CXlMPACl'

The Rio Grande Catpact provisions limit the arrount of water all=ated
to Colorado, and require that a varying percentage of streamfla.v
be available at the Colorado-NEW Mexico boundary for da.vnstream
users in NEW Mexico, Texas and Mexico. During the past 2-3 years
Colorado has released to the dCMlstream users more water than
required on an annual basis by the Compact. Late priority water
for Colorado users has been shut off at times in the San Iuis
Valley and passed c:lc:Mn stream to rreet Catpact requirements
resulting in hardship to sare Colorado users.

NEW arrangements for rreeting this problem have been worked out
between the Colorado State Engineer and water users in the valley.

Compact provisions restrict use of storage reservoirs in part of
the San Luis Valley. Where restrictions apply, the Catpact provides
that (1) Colorado may not increase the arrount of water in storage
in reservoirs constructed after 1929 whenever there is less than
400,000 acre-feet of water in Elephant Butte Reservoir, and (2)
in N:Jvember of any year Texas or NEW Mexico may demand release
of water fran storage reservoirs constructed after 1929 to the
arrount of the accrued debits of Colorado.

The State Engineer of Colorado interprets the Catpact restrictions
for storage reservoirs as not applying to streams entering the San
Luis Valley from the east which do not reach the Rio Grande River,
and tributaries to the closed basin.

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