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Irrigation Guide
IRRIGATION GUIDE
Northern Zone, North of Kamm Ave.
Central Zone, Kamm Ave. to Dorris Ave.
Southern Zone, South of Dorris Ave.
The Irrigation Guide presents real-time crop ET information and has been provided weekly to all water users since the Water Conservation Program began in 1978, using the USBR Irrigation Management Service computer program. As of December 1998, 528 copies of the Irrigation Guide were being sent out each week. Half of the Guides were delivered via FAX. Since the Guide is usually a single side of a page, FAX delivery is a considerable cost saving option where applicable. In 1999 a weekly email version was initiated and in 2000 this daily version was made available.
Crop ET information is necessary to develop efficient crop irrigation schedules, both real-time and average yearly values. Three automated weather stations are used to provide real-time ET information currently serve the District; one operated by the District and two that are part of the CIMIS network. Currently Westlands Water District, Tranquillity Irrigation District, Broadview Water District and CIMIS cooperatively operate the northern weather station site.
Farmers know their soil, climate, and crops. But for some, determining precise crop water needs, maintaining water use records, and calculating irrigation efficiency is a matter of tradition and practical experience. Armed with reliable information in a practical format, these farmers are better equipped to schedule irrigations and apply the correct quantity of water for their specific field conditions.
This information was originally based on a manually operated weather station located at the District's Tranquillity Field Office. District climatic measurements are now obtained from the automated weather stations and are used to develop specific water use values to help farmers estimate crop water use and schedule irrigation timing and amounts.
Daily water use for various crops is presented in the Guide. This includes actual daily water use for the past 28 days and a 10-day forecast of crop water use based on National Weather Service forecasts and average historical weather conditions. The Guide also includes information on precipitation at the three weather stations in the District and at Shasta Dam and on water storage quantities at San Luis Reservoir and Lake Shasta. On the reverse side of the Guide, water conservation information is printed, including upcoming events and deadlines, available assistance, and management tips. Project water quality has recently been added. Clicking on the crop name for any crop on the Guide will link to a Fieldman Scheduling Sheet (FSS) for that crop. The FSS presents information, calculated from the Guide data, in a grid that can be used to minimize the calculations necessary to calculate the current depletion based on the date of the last refilling irrigation and the desired date. This page can be printed out to be taken into the field.
The data shown in the Guide are the result of extensive monitoring between 1982 and 1995 of the various crops grown in the District to verify and calibrate the computer model used to calculate the crop water use values. While the Guide information has proved very accurate, each water user is encouraged to conduct regular soil moisture monitoring with the "feel" method or other means to verify the soil moisture status of each field. Farmers also are encouraged to apply only the amount of water necessary to refill the crop root zone and satisfy salinity control and other cultural water needs. Comments from farmers during routine contacts and District-facilitated focus groups indicate a high level of utilization of the Guide. Some farmers use the Guide's crop water use information to confirm other methods, while many use it directly to schedule irrigations.