PUB00027

• Year: 1990
• Title: Final Report Rio Grande Water Supply Study, Phase 1
• CWCB Section: Interstate & Federal
• Author: San Luis Valley Water Conservancy District
• Description: Reconnaissance level determination of the physically and legally available flow at 4 reservoir sites in the Rio Grande Basin upstream of Del Norte, Colorado
• Publications - Doc Type: Brochure

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shown on Figure 11-3. Almost all of the mainstem water rights from the Rio Grande

headwaters to the stateline are in District 20. Of the mainstem water rights from

the confluence with the South Fork to the stateline. all but one are in District

20. The listing of approximately 310 mainstemwater rights in District 20 (prepared

by the water administrators) has been included as Appendix A.

Since water districts other than District 20 lack major mainstem water rights which

would significantly affect water availability at the potential reservoir sites,

investigations of water administration in these districts were not considered.

Interviews were conducted with Steve Vandiver, the Division 3 Engineer, and Max

Nash, the District 20 Water Commissioner, to learn about water administration which

would affect water availability to a new reservoir. The steps performed in

allocating water in District 20 are summarized below.

1.

Based on runoff forecasts issued prior to the runoff season, the Division

Engineer estimates the portion of the Rio Grande flows at Del Norte which

are required to satisfy the Rio Grande Compact and provides the Water District

20 Commissioner with a "curtailment percentage" of Del Norte flows which have

to be passed during the irrigation season to satisfy Compact obligations.

See Section IV for more detailed discussion of the factors involved in this

determination.

2.

In detemining the Del Norte flows available for allocation, the water

commissioner first subtracts the transmountain diversions and reservoir

releases from the measured Del Norte flow. The transmountain diversions and

reservoir releases are not available for general allocation since they are

designated for particular diversion systems.

3.

The water commissioner then determines the water available for allocation

when considering the Compact. To do this the flow calculated in 2. (adjusted

flow) is mul tiplied by the curtailment percentage and the result is calculated

flow. This water is then made available to Colorado water users by proceeding

down a list of decreed water rights ranked by priority (Appendix A) and

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