FLOOD10357

• Document ID: 123
• County: Rio Grande
• Stream Name: Alamosa River
• Basin: Rio Grande
• Sub-Basin: Alamosa - Trinchera
• Water Division: 3
• Title: Alamosa River Watershed Project Literature and Watershed Assesment, Final EPA Report
• Date: 9/30/2003
• Prepared For: Valle del Sol Community Center
• Prepared By: US Environmental Protection Agency
• Watershed Pro - Doc Type: Project Report

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4.4 Instream Flow Issues

There has been an interest by local citizens and groups in the watershed to explore the
possibility of committing abandoned water rights to the Alamosa River for year round
instream flows. Portions of the Alamosa River, especially near Capulin are dry the
majority of the year. The lack of flow impairs the aquatic'life, and the aesthetic and
recreational value of the river corridor. Stream flow has been impacted by a previous
Army Corps of Engineer project that severely impacted groundwater infiltration into the
river and Terrace Reservoir operations.

According to Steve Vandiver (Division III Engineer, Division of Water Resources), all of
the water rights on the Revised Abandonment List are very junior and do not come into
priority on a regular basis. These abandoned water rights have little historic use and
have not been exercised within the past 10 years. Mr. Vandiver stated that these rights
would provide little or no water that would be transferable (28). In regards to using the
Terrace Reservoir pool that is above the current operational level of the reservoir (2000
acre feet), Mr. Vandiver feels that amount of water is not enough to provide a pool for
instream flows much of the year. However, it is not mentioned in the water resources
report what the actual instream flows suggested by the citizens would be to sustain
instream flows.

According to the Colorado Department of Water Resources, there have been
suggestions that a new reservoir be built in the headwaters or just below Terrace
Reservoir to store excess water for instream purposes. There are concerns by the
Region III Engineer regarding this proposal:

1. The amount of water that could be stored is very low and would provide little flow to
the Alamosa River.
2. In high runoff years with excess water, the water is to be sent to fill valid rights on the
Rio Grande River; it is the opinion of the Colorado Water Resources District that the
. Alamosa River is a tributary of the Rio Grande River.

It is the opinion of the Region III Engineer that it would take too much water (4250 acre
feet annually) to support a minimal instream flow in the Alamosa River at Capulin and
would deplete a very large area of irrigation groundwater under a very senior right. Icing
would also cause water to leave the channel and possibly flood property in and along the
floodplain.

4.5 Stream Classifications and Standards

The Alamosa River has gone through a numerous changes in the past several year that
involved: 1) re-segmentation of the river, 2) redesignation of uses and 3) changes in
water quality standards. Much of the re-segmentation of the Alamosa River is base
upon the impact from the Summitville Mine and the results from Use Attainability
Studies.

The Colorado Water Quality Control Commission (WQCC) has classified and
established numeric standards for all of the Alamosa River and its major tributaries.
Table 1 summarizes Regulation 36 of the Classification and Numeric Standards for Rio

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