WSP03326

• File Number: 8583
• Description: Rio Grande Decision Support System
• State: CO
• Basin: Rio Grande
• Water Division: 3
• Date: 3/9/1998
• Title: 1997 Calendar Year Report to the Rio Grande Compact Commission
• Water Supply Pro - Doc Type: Report/Study

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Pojoaque Tributary Unit. Nambe Falls Dam and Reservoir

Nambe Falls began 1997 at a storage of 1,346 af (6813.33 ft) and ended with 1,546 af
(6,817.66 ft). During the winter, releases averaged about 1.0 cubic feet per second (fts/s),
to maximize conservation storage as agreed to by the Pojoaque Valley Irrigation District
(PVID) and Indian water users. Winter storage operations caused the reservoir to fill and
spill from March 22 to April 10. Irrigation releases took place from April 10 to 29 which
brought the reservoir down before an above average spring runoff (113%) filled and spilled
the reservoir again from May 9 to July 13. A maximum release of 78 {f/s occurred on June
9. Irrigation releases began again on Jufy 14 and continued off and on throughout the
irrigation season and ended on October 27. A maximum release, during irrigation season,
of 38 fis/s was reached on July 15 and 20. Summer rains again filled and spilled the
reservoir from August 15 to 27. The reservoir then continued to decline for the remainder
of the irrigation season reaching its lowest point of the year on October 27 at elevation
6,809.61 ft (1,185 af). As a result of the reservoir's cyclical operation, a higher than normal
depletion of 1,374 af was computed at Otowi (which was by coincidence the same amount
computed last year). San Juan-Chama replacement water was released in February, July,
August, and December to offset the depletions for Nambe Falls operations in the amount
of 1,402 af (equivalent release from Heron). A summary of the SJ-C water at Otowi is
shown in Table 5 and the Nambe Falls Reservoir operation in Table 6.

Under the Technical Assistance to States Program, Reclamation performed a sediment
survey at Nambe Falls ResElrvoir in July 1997. New area-capacity tables are being
generated by Reclamation and will be available by March 1998.

As part of Reclamation's Native American program, a water measurement device will be
installed on the Rio Nambe upstream of Nambe Reservoir. The device will provide for a
more accurate measurement of the inflow into Nambe Falls Reservoir.

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Sediment Deposition in U.S. Army Corps of Engineers' Reservoirs

At Abiquiu Reservoir, Public law 97-140 authorizes storage of up to 200,000 af of SJ-C
Project water. Adjustments for sediment reduced the available storage allocations to
181,691 af in 1997. See Table 9 for Abiquiu Reservoir operations.

At Cochiti lake, the SJ-C pool was adjusted monthly to compensate for displacement of
SJ-C content by deposited sediment. The maximum allowable surface acreage (including
wetlands) of the SJ-C pool is 1,200 acres.

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San Juan-Chama deliveries to replace losses from the Cochiti lake's permanent recreation
pool are usually performed in accordance with the recommendations made in the Cochiti
lake Re-regulation Interagency Biological Report published in June 30, 1993. There was

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