PROJ00509

• Contract/PO #: C153500
• Contractor Name: San Miguel Water Conservancy District
• Contract Type: Loan
• Water District: 0
• County: San Miguel
• Bill Number: XB 99-999
• Loan Projects - Doc Type: Feasibility Study

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CHAPTER IV . WATER DEMANDS

Water use in the San Miguel study area reflects the agricultural nature of the region with irrigation water

demands accounting for about 98 percent of water usage, In this chapter, historical water use is reviewed. Future

agricultural water demands are then discussed in terms of a projected cropping pattern, crop water requirements

and irrigation system characteristics. Future municipal and industrial demand projections are presented in terms

of population and employment projections.

Historical Water Use

Records of historical water use in the project area are very limited, However, a review of the records that are

available indicates that water deliveries have typically been siguificantly less than crop requirements. That is the

reason for this study and the reason why facility improvements are needed to increase water delivery capability.

Figure IV -1 shows average historic reservoir operations in the study area based on four years of available records.

Historic inflows to existing project reservoirs average about 29,000 acre-feet annually and occur mainly in April,

May and June coincident with spring snowmelt runoff. Inflow in July, August and September is minimal. Historic

reservoir operations have been limited due to diversion intake and ditch conveyance capacities, existing storage

capacities and runoff volumes in dry years.

The existing reservoirs do help the problem somewhat by storing some early season runoff and releasing this water
later in the season to more closely match demand. It can be seen from Figure IV-I, however, that in the months
of June, July, August and September that demand far exceeds release capability. Improved diversion, conveyance
and storage facilities along with modifications to the existing cropping patterns and improvements in operating
and irrigation efficiencies would help provide a more reliable water supply and better meet late season demands.

The existing irrigation facilities (see Figure II-I) and their operation are distinct with each ditch company. A
description of the facilities of each ditch company and their operation follows.

The principal components of the Gurley Ditch system, which is owned and operated by the Farmers' Water
Development Company, consist of the Gurley Ditch, Gurley Reservoir and Redvale Reservoir, Gurley Ditch
diverts water from tributaries of Beaver Creek, conveys the diversions to Gurley Reservoir where they are

IV-I