Irrigation Design in Montana: Accommodating varying water accessibility across the continental divide.
Date of Graduation
Bachelor of Science in Biological Engineering
Biological and Agricultural Engineering
Le, Kieu Ngoc
Committee Member/Second Reader
The design work performed in this project was conducted over two summers (2018, 2019) of internship experience with the Natural Resources Conservation Service (NRCS) across the state of Montana. The first summer’s design work was based out of Glendive, MT, in Dawson County, approximately 50 kilometers from the North Dakota border. The second summer was in Missoula, MT, in Missoula County, near the Idaho border. The two areas differ significantly in topography, weather, and water availability with the main separating geographic influence being the Rocky Mountains.
This paper focuses on the design process and requirements for two farms located outside Glendive, MT and outside Stevensville, MT. The locations will be referred to in this document by their county locations, Dawson County and Ravalli County, respectively. Dawson County is on the far east side of Montana, and Ravalli County is on Montana’s western border.
With both locations in the same state, they follow the same NRCS design standards. However, the design requirements, systems implemented, and crops grown can differ significantly between the two regions. In Dawson County, on the east side of Montana, many farmers with fields greater than 20 hectares have converted their irrigation systems to center pivots for irrigation. This transition is largely a result of the center pivot’s ability to tightly control the application rate of water, resulting in a higher yield per gallon applied. Additionally, the cost of installation for a center pivot is significantly cheaper per hectare on the large fields compared to fields smaller than 10 hectares. In contrast, farmers in Ravalli County operate in smaller fields of around 4 hectares. These farmers historically use severely inefficient irrigation systems such as wild flood irrigation and are switching to more efficient systems such as hand and wheel line. At their relatively small operational scales, it would typically be financially inadvisable to install a center pivot on the land.
The NRCS is not able to directly reach out to farmers and propose or require implementations for land management practices. The NRCS is a non-regulatory agency, as such it offers assistance to those who ask for help, rather than mandating changes to the farms. At this point, the NRCS can begin helping the farmers improve their land management. The NRCS will work with farmers so that they can become better land stewards. A large part of the NRCS’s engineering design work is in irrigation systems. The NRCS works to minimize water usage to meet the needs of the crops as well as minimize soil erosion. These designs were the primary responsibility of the author during his internship. The design for a farmer in Dawson County was replacing his old tow line irrigation system with a center pivot irrigation system. Upgrading this system resulted in a projected water use reduction, decreased labor, and increased the irrigable season (NRCS New Mexico, 2012). The design in Ravalli County provided an upgrade from a wild flood system to a wheel line system, increasing the farm’s irrigation efficiency from 30% to 65%.
agriculture, NRCS, engineering, water, montana, irrigation
Lampson, J. G. (2020). Irrigation Design in Montana: Accommodating varying water accessibility across the continental divide.. Biological and Agricultural Engineering Undergraduate Honors Theses Retrieved from https://scholarworks.uark.edu/baeguht/68
Environmental Engineering Commons, Natural Resources and Conservation Commons, Sustainability Commons, Water Resource Management Commons