The All-American Canal brings water from the Colorado River at Imperial Dam to the farmland of the Imperial Valley. Three main canals, the East Highline, Central Main and Westside Main divert water from the All-American Canal and distribute to smaller lateral canals throughout the Imperial Valley. Farmers receive water directly from the lateral canals to irrigate nearly 500,000 acres of farmland within IID's water service boundaries. Another important component of IID's distribution system are the seven regulating reservoirs and four interceptor reservoirs that have a total storage capacity of more than 4,300 acre-feet of water.
IID serves water through approximately 5,600 delivery gates for irrigation purposes. It operates and maintains more than 1,400 miles of lateral canals, 230 miles of main canals and the 80-mile-long All-American Canal. IID also maintains over 1,450 miles of drainage ditches used to collect surface runoff and subsurface drainage from over 32,000 miles of tile drains underlying nearly 500,000 acres of farmland. Most of these drainage ditches ultimately discharge water into either the Alamo River or New River.
Each October, the USBR asks IID to estimate the amount of water it will need to divert from the Colorado River during the following calendar year, commonly referred to as the annual water order. In addition to the annual water order, weekly water orders are also submitted to the USBR.
Each Wednesday, IID's watermaster submits a weekly water order to IID’s River Division office for the following week's (Monday through Sunday) water requirement. These water orders are derived from historic and recent orders from IID's water customers. IID’s River Division collects the weekly water orders from all Imperial Dam users and relays the request to the Yuma Area Office of the USBR. After the USBR has accumulated the water orders from all water users on the lower Colorado River, it then prepares a master schedule of flows to be released from Hoover Dam.
The amount of water scheduled on the weekly master schedule is the amount of water IID may use at Imperial Dam on the delivery date unless that order is revised 3 days before the delivery date.
Water customers can order water until noon of the day before the delivery date. Division staff enters the water orders into TruePoint (IID’s lateral scheduling/delivery system), around noon. Once all water orders have been entered into TruePoint, the Dispatching Unit analyzes the demand for water and distributes the available water to the water sale areas: Holtville, Southwest, Brawley, Calipatria and Westmorland. During this time the Dispatching Unit will also revise IID’s master schedule order for 3 and 4 days in the future.
Delivering Water to the Customer
Water Division sections will use the water allotted to them to schedule deliveries in their areas. When there isn’t enough water or canal capacity to meet all delivery requests, some orders are “carried over” to the next day. Once the Divisions have scheduled the laterals and main canal deliveries, the Dispatching Unit can schedule the next day’s main canal flow. All scheduling for main canals uses a custom built program utilizing SCADA, current lateral discharges, and the next day’s TruePoint lateral schedule. The Dispatching Unit uses the custom program to prepare a water plan for the following day’s water deliveries and schedules the required changes throughout the main canal system in order to best meet water user demands.
Each morning, zanjeros (Spanish for "ditch riders") measure and release the required amount of water from the main canal into the heading of each lateral canal scheduled to receive water. The zanjeros then use a "run" schedule (instructions for when and where delivery gates should be opened or closed) to divert water from the lateral canal through individual customer delivery gates. Runs are comprised of a set of canals and all the associated customer delivery gates within a geographic area. Many zanjeros can adjust their headings using a mobile computer that tracks crucial water levels throughout the day.