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Closed Basin Project


The Reclamation Project Authorization Act of 1972 was passed on October 20th, 1972 and gave authorization to the U.S. Bureau of Reclamation to construct, operate and maintain the Closed Basin Division in a series of five stages. The Closed Basin Division is located in Alamosa and Saguache Counties.

Click here to view a map of the Closed Basin Project.

The large section of the San Luis Valley, north of the Rio Grande between Del Norte and Blanca does not have a surface outlet into the Rio Grande and is what coined the term “The Closed Basin Area.”  At the southern end of the Closed Basin area is a hydraulic divide that separates the internal drainage area of 2,940 square miles from the Rio Grande mainstream.   Although the Closed Basin area waters are still tributary waters, as dictated by laws set by the State of Colorado and the United States, they have been “duly appropriated for the project by the Rio Grande Water Conservation District (RGWCD).”


The purpose and first priority of the Closed Basin Project is to deliver water to the Rio Grande to assist the State of Colorado in meeting its delivery requirements under the Rio Grande Compact of 1939 and the Rio Grande Convention of 1906.  The second priority of the project is to maintain the Alamosa National Wildlife Refuge (NWR), provided, that the amount of project salvaged water delivered to the NWR and The Blanca Wildlife Habitat Area (WHA) shall not exceed 5300 acre feet annually.  The third priority is to apply to the reduction and the elimination of any accumulated deficit in deliveries by Colorado and is no longer applicable since the spill of Elephant Butte in 1985.  The fourth and final priority is for irrigation or other beneficial uses in Colorado.   The project also delivers mitigation water to San Luis Lake complex and its recreational facilities.                                                        
The Closed Basin Project obtains its water from the salvaged unconfined aquifer groundwater within the Closed Basin and is delivered to the Rio Grande by a 42-mile conveyance channel.  The RGWCD owned the rights of up to 117,000 acre feet of water per year from the water that is salvaged from the Closed Basin Project. Due to inadequate water supply the RGWCD voluntarily reduced the right to 83,000 acre feet per year. Approximately 43,000 Acre Feet has been decreed absolute and the remaining 40,000 acre feet are still a conditional right. As of 2000 the total project delivery (amount of water delivered to the river and refuges (BLM and USFWS) has averaged approximately, 17,300 acre feet per year.  

Salvage Wells

When the project was constructed 170 water salvage wells were completed and comprised the core of the Closed Basin Division.  Currently, there are only about 110 to 120 water salvage wells that are pumping due to draw downs, water quality and iron bacteria. These wells pump from the unconfined aquifer and range from about 85 to 110 feet in depth and do not penetrate the “Blue Clay” layer.  The original wells are enclosed in concrete vaults below ground and pump 50 to 400 gallons per minute.  Even though all existing 170 wells are in a vault; there have been numerous wells re-drilled, putting the well–head above ground due to bio fouling issues in the original wells.

Observation Wells

Currently, there is a network of over 132 wells that are used to measure water level or pressure data from both the confined and unconfined aquifers.  The data that is retrieved from these measurements is used to operate the Closed Basin Project within the limits that are prescribed by the authorizing legislation.

Pipeline Laterals

There are about 115 miles of pipeline laterals within the Closed Basin Project.  These laterals operate under low pressure and transport the salvaged water from the salvage wells to the conveyance channel.

Conveyance Channel

The conveyance channel is about 42 miles in length and a width that has a design capacity increasing from 45 ft3/s to a maximum of 160 ft3/s.”   The conveyance channel collects the salvage water from the pipeline laterals and delivers it to the Rio Grande at a flow velocity of about 1ft/s.  There is also an additional five miles of pipe carrying the salvaged water from stage five.

Programmable Master Supervisory Control System (PMSC)

The PMSC is a remote system that is located at the office of the Bureau of Reclamation in Alamosa. The PMSC helps maintain the required water quality at the point of delivery; it regulates water deliveries, detects equipment problems, and obtains and stores operation data using remote terminal units (RTU’s).   The RTU’s are located at each salvage and observation well sites along with other control points and use ultra-high frequency (UTF) communication to transmit the data to the master station in a cost efficient manner. 

Operation and Maintenance

The RGWCD provides the civil maintenance on the Closed Basin Project as agreed upon in the cooperative agreement while the Bureau of Reclamation operates and maintains the project.

As part of the operating criteria there is an operating committee which monitors the Closed Basin Project.  The operating committee is composed of three members:

  • One member is appointed by the Secretary of the Interior
  • One member is appointed by the Colorado Water Conservation Board
  • One member is appointed by the Rio Grande Water Conservation District

This operating committee is to determine if the requirements of Section 102 of Public Law 92-514 as amended are being complied with.

San Luis Lakes State Park

The Bureau of Reclamation, the Colorado Water Conservation Board and the Colorado Division of Wildlife worked together to construct recreation facilities at the San Luis lakes.  Funding for the park is primarily provided by the State of Colorado, but when additional funding is needed RGWCD lends a helping hand.