Currents: Water Sage's Blog on Water Rights and Water Data

January 11, 2016: MT Irrigators: Pivot Conversions Require Water Right Changes
Nancy Zalutsky
MT Irrigators: Pivot Conversions Require Water Right Changes

Farmers are always trying to do more with less, and water use is no exception. Since no one has figured out how to produce more water, farmers need to irrigate more efficiently. The drought conditions in California have persuaded farmers to use a variety of methods to conserve water, including the use of drip irrigation systems, timers, and irrigation scheduling based on weather forecasts and moisture conditions.  Whether you are dealing with drought or trying to increase productivity and cut irrigation costs, water conservation makes sense. Here in Montana, converting old flood systems to sprinkler pivot systems is a common upgrade on farm and ranch properties.

Flood irrigation uses contour field ditches and movable dams to apply water to the fields. Although flood irrigation may get the job done, it is only about 45-50% efficient while modern sprinkler systems are up to 85% efficient. Also, flood irrigation requires hours of work in the fields moving dams and opening or closing ditches. For farmers who want the most efficient way to irrigate, modern automatic sprinkler systems can help, especially if soil moisture meters and sensors are used to determine how much irrigation is needed. One Montana farmer installed a center pivot irrigation system after years of flood irrigating.  The center pivot allows him to uniformly apply and keep track of how much water he is using for his crops. He also eliminated 14 miles of the surface ditches and seep-out spots. Another way to improve water efficiency is to replace open canals and ditches with pipelines. Another Montana farmer cut out 5 miles of canals and eliminated the need for pumps by installing 11,600 feet of buried plastic pipe.  While converting irrigation techniques can boost efficiency, there are costs and impacts to other water users to consider.

Irrigation improvements benefit the water user and the environment by allowing the farmer to produce a crop while leaving more water in the source, but they require financing and technical help. The USDA Natural Resources and Conservation Service (NRCS) provides both financial assistance and technical assistance for irrigation and conveyance systems and irrigation monitoring equipment. Montana NRCS’s Irrigation Water Management (IWM) project uses crop and weather data to help landowners improve how they manage water by helping farmers keep track of the day-to-day moisture needs on their land. IWM includes an Excel spreadsheet that has formulas to monitor and balance soil moisture in irrigated areas, flow meters to record flow rates and total volume usage, soil moisture meters and sensors to monitor soil water deficit, and soil moisture data loggers to record soil moisture history throughout the growing season.

Before the invention of all these new gadgets that monitor usage, plant conditions and soil moisture, farmers saved water and labor primarily by converting from flood irrigation to sprinkler irrigation. Conversion from flood to sprinkler irrigation often involves moving points of diversion and reconfiguring the field. Because you may change the place, point of diversion and the way you use water, your change may adversely affect other water users. Therefore, the Montana Water Use Act requires a water user to obtain authorization from the Department of Natural Resources and Conservation (DNRC) in order to change the place of diversion, the place of use, the purpose of use, or the place of storage. M.C.A. §85-2-102(6). In the 1970s and 1980s, water users didn’t realize that they needed to apply for a change authorization to use their sprinkler system. Many of them still don’t know they need to apply for an authorization to move their point of diversion or reconfigure the place of use from a square to a circle if that circle irrigates different acreage. In fact, from 2011 to 2015, the Montana NRCS provided financial assistance for 292 projects including converting flood system or wheel lines to pivot systems, an average of 58 projects each year. During the last 3 years, the DNRC received only 41 change applications that involved changing some portion of historic flood irrigation to sprinkler irrigation.

Many farmers still overlook the change requirement when they are planning changes to their irrigation system, and, it’s not a small matter. Regardless of prior District Court or Water Court decrees, applicants are required to prove historical beneficial use for the change authorization process, part of which entails the DNRC evaluating how much of the water diverted has actually gone to the prescribed use. Obtaining a change authorization can take over a year and cost tens of thousands of dollars. You cannot use any more water than you have in the past, so you need to be able to prove the historic use of your water rights. You should be prepared to have your water rights decreased during the process and be sure the project is still financially viable.  While the process may seem daunting, applicants are not without resources.  The Montana DNRC operates field offices all over the state with professionals equipped to advise and support people through the application process.  If you are considering a conversion, a conference with your local DNRC office is a great place to start.