Background

The irrigation district was originally established in 1928 and covers 64,828.12 acres. The district delivers water to 47,000 acres of irrigable land under 4,000 water accounts. In addition, it provides raw water to five municipalities—Alamo, McAllen, Pharr, San Juan and Edinburg— and the North Alamo Water Supply Corporation.

The district pumps water directly from the Rio Grande into a settling basin (reservoir) via a gravity canal and then into a conveyance system of pipelines and canals. In 2002, the district had an overall estimated conveyance efficiency of 80 percent, which indicates an average water loss of 11,176 acre-feet from evaporation and seepage.

The open-air, concrete-lined Wisconsin Canal extends two miles through the northeastern part of the district. The canal serves 1,872 acres of land and is supplied by a 48-inch reinforced concrete gravity pressure main from the district’s reservoir. Originally constructed in 1911 without any barrier lining, the canal is now severely cracked and ongoing seepage will eventually result in its failure.

Description

The proposed project consists of replacing the open-air canal with pipeline, and includes the following major components:

• Construction of two miles of 48-inch reinforced concrete pipeline with gates and/or valves to control flows
• Replacement of farm turnouts designed to accommodate the use of portable meters
• Construction of drain turnouts at the end of each lateral pipeline and a surge structure at the end of the new pipeline

Benefits

The project will reduce water losses from seepage and evaporation, resulting in an estimated savings of 977 acre-feet of water a year. Energy savings from reduced pumping requirements are estimated at 109,289 KWH/year on average.