VALLEY — Pursuant to a temporary agreement with the Rio Grande Water Users Association and the State and Division Engineers, as part of its planned rehabilitation of Rio Grande Reservoir the San Luis Valley Irrigation District has begun and will continue to evacuate water from the reservoir to ensure that by mid-October the reservoir is effectively empty except for a small quantity of water behind the temporary coffer dam.
Approximately 6,000 acre-feet of water to be released is so-called “compact water” that was stored at the direction of the Division Engineer during past irrigation seasons. This is water that if not stored would have been delivered in the Rio Grande to the Colorado-New Mexico state line as a delivery under the Rio Grande Compact, not diverted by ditches on the Rio Grande. The Division Engineer directed the storage of this compact water to assist him in efficiently administering the compact and minimizing excess deliveries. Some of the compact water has already been moved to Santa Maria, Continental and Beaver Reservoirs, but stream flows were too low to allow all of it to be moved to other reservoirs.
There has been no compact curtailment of water rights on the Rio Grande in 2018 due to the very low stream flows. The Division Engineer projects that even without any curtailment for compact purposes, the Rio Grande will meet, and likely exceed its 2018 scheduled delivery under the compact. The delivery of the compact water from Rio Grande Reservoir to the state line in 2018 would result in an even greater over-delivery and a loss of some of that water to evaporation in Elephant Butte Reservoir before it could be reclaimed by Colorado.
To save this water for future use on the Rio Grande in Colorado, under the temporary loan agreement, the irrigation district estimates that it will release the remaining compact water from Rio Grande Reservoir at rates of 50-100 cfs and divert that water into the Farmers Union Canal between now and early October.
The district will replace the water in Rio Grande Reservoir in the following years when the reservoir has been repaired and can again store water. The parties to the agreement have agreed that this is the best way to ensure the water remains available to benefit water users in Colorado in future years.
The repair work at Rio Grande Reservoir will include modifying the outlet works, bypassing the existing gate chamber, and providing flow control at the downstream end of the outlet tunnel. Initial preparation has begun and will continue during this summer and fall. Construction will begin on November 1. The work will continue through April 1, 2020, when it is scheduled to be completed.
Because the reservoir will not be able to store water until February or March 2019, water that it would have otherwise been stored will be released from the reservoir and when delivered to the state line will help meet the Rio Grande’s compact schedule and accounted against the amount of compact water the irrigation district must repay.
For more information please contact Rob Phillips, superintendent of the San Luis
Valley Irrigation District at (719) 754-2254. More information of the rehabilitation of Rio Grande Reservoir is available at the irrigation district’s website: