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WWRC 85-32
An Analysis of Irrigation Strategies Under Increasing Electricty Costs and Declining Groundwater Levels

Introduction

In recent years, irrigators in Laramie County, Wyoming have faced a difficult combination of factors. Increasing electricity costs, low crop prices and declining groundwater levels have served to reduce the profitability of crops produced using center pivot irrigation systems. Such economic pressure provides an incentive for irrigators to consider alternative management strategies which may improve the economic returns from center pivot irrigation systems. Similarly, because groundwater levels are declining, strategies can be considered to lengthen the physical and/or economic life of the aquifer.

The purpose of this report is to provide an economic analysis of various management strategies for center pivot irrigated farms in Laramie County, Wyoming. The study uses a model of a typical farm using center pivot irrigation to assess the impact of alternative strategies on returns to land and management. An evapotranspiration/yield model and a pump-cost model simulate yields and pumping costs for the representative farm. The results from these two simulation models are used as inputs for a linear programming model which determines the optimal crop mix and associated returns under alternative irrigation strategies. The management strategies considered In this study are:

  1. Converting from high to low pressure center pivot systems;

  2. Increasing pump and application efficiencies;

  3. Participation in a load control program;

  4. Potato farms;

  5. Voluntary restrictions of water use of 10% or more; and

  6. Restricting the amount of water pumped from the aquifer through a government imposed restriction policy.

Results of the analysis indicate that the most promising strategies with respect to the profitability of center pivot irrigation are:

  1. Conversion of center pivot systems from high pressure to low pressure;

  2. Improving pump and/or application efficiencies;

  3. Participation in the direct load control program;

  4. Potato farming; and

  5. A non-restriction policy on water pumped from the aquifer.

Section two of the study provides a brief review of previous work on irrigation pumping from the Wyoming Ogallala Aquifer as well as an update on trends in irrigated farming. A discussion of the limitations of previous work is given in section three. Section four outlines the mathematical models and methods used in the analysis. Finally, section five presents the results for the various management strategies considered.

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