WSP11716

• File Number: 8507
• Description: Rio Grande Project
• State: CO
• Basin: Rio Grande
• Date: 7/1/1997
• Title: Water Management Study: Upper Rio Grande Basin part 1
• Water Supply Pro - Doc Type: Report/Study

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Major Physical, Legal, and Institutional Characteristics

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1950

1960

1970

1960

1990

Figure 1.1.-Natural flows of Rio Grande at Otowi Bridge in New Mexico (index supply).
Source: ECONorthwest with dam from the Rio Grande Compact Commission (1939-94).

between 1,587,000 and 536,000 af(Hydrosphere Inc. 1993). The lower end
of this scale, 536,000 af, demarcates a low-flow year in this reach of the
Rio Grande. Records for 1950(1993 indicate that low flows occurred in 1950,
1951, 1953(56, 1959, 1963, 1964, 1972, 1974, 1977, 1980, and 1981. Barring
unforeseen events, 1996 also will prove to be a low-flow year.

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About two-thirds (on average, 700,000 af/yr) of the water entering the Middle
Rio Grande reaches Elephant Butte Reservoir, which serves as the
measuring point for determining the amount of Rio Grande water New
Mexico delivers to Texas (Rio Grande Compact Commission 1991).3 The
balance, approximately 350,000 aflyr, is consumed by agriculture and
municipal users or "lost" through seepage and evaporation as the river water
moves through the Middle Rio Grande area. Agricultural users account for
about half of the water used or "lost", and municipal users and transporta-
tion each account for about one-quarter. In 1990, agricultural users in the
Middle Rio Grande, on average, diverted 404,000 af and consumed 181,600 af
(Wilson 1992). The area's municipal users diverted 155,000 af and consumed
82,200 af(Wilson 1992). Transportation and evaporative losses accounted

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3 The Rio Grande Compact defines the minimum fraction of the water passing Otowi
Bridge that must reach Elephant Butte Reservoir. See the discussion ofthe Compact that
follows.

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