A griculture is a major user of water in the United States. How the industry utilizes water resources through irrigation technologies and best management practices continues to be a focal point of agriculture policy. Given the increasing demands on water supplies for other users and uses, especially for the urbanizing West, there are pressures for the agricultural industry to reduce its water footprint. The use and significance of irrigated agriculture varies widely across the United States. In 2012, farms with irrigated land accounted for 50% ($106.3 billion) of the market value of crops sold in the United States, with roughly 71% of irrigated farms residing in the 17 western states. Drought and heat events, as well as agricultural market conditions, have raised agricultural producers' interest in investing in irrigation systems and improved irrigation practices; these producers often are weighing the benefits of irrigation-related investments with their costs. Agricultural water use and irrigation practices raise a number of policy questions. The report is intended to provide an overview of on-farm irrigation and does not cover storage and conveyance prior to the farm or how irrigation adoption may alter other farm practices, such as the use of fertilizers and pesticides or impacts off-farm (e.g., groundwater and surface water quality concerns). Growth in irrigated acres in the West is small when compared to increases in the East. This is determined by several factors, including irrigation system performance, uniformity of water application, and crop response to irrigation. Additionally, even if measures are taken to limit increased water consumption (e.g., limiting additional irrigated crop acreage after conversion to efficient irrigation systems), efficient irrigation technologies may encourage farmers to grow more profitable, water-intensive crops. While these two categories cover basic irrigation, precision technologies to increase irrigation efficiency and reduce costs complement these systems and are increasingly becoming a common part of modern irrigation systems. Best management practices (BMPs) for irrigation center around how water is managed on a farm, including improved conveyance, irrigation scheduling, and application methods. As shown in Table 1 , pressure irrigation systems make up roughly 58-65% of irrigation systems used in the United States. Microirrigation

Microirrigation consists of several types of low-pressure, highly efficient irrigation systems including surface drip, micro sprinkler, and sub-surface drip irrigation ( Figure 10 ). Gravity Systems

Gravity systems, which make up 35 to 42% of irrigation systems in the United States, divert water from a source to flood over a crop area via land-forming measures, including canals, ditches, basins, and furrows ( Figure 10 ). Precision technologies, such as satellite data, sensor networks, data analytics, and drones, increase irrigation efficiency and have been reported to reduce input costs and increase crop yield. In some cases, irrigation BMPs enhance production of higher-value specialty crops, including fruits, vegetables, and nuts, by allowing water to flow to crops only when needed. This can also reduce costs and provide more precise application. As a result, high-efficiency pressure systems are commonly found in areas where there is a heavy reliance on groundwater. Water quality can dictate the type of irrigation system that can be used. Federal Assistance

The federal government provides agricultural producers with financial assistance, technical assistance, research, and monitoring and reporting. Technical Assistance

USDA provides technical assistance for the adoption of irrigation technologies through a number of agencies and programs. Appendix A. Irrigation Technologies and Water Use 
Appendix B. This method focuses on crop yield sustainability and water conservation.
Recent threats to water availability as a result of moderate to exceptional drought in several states have raised questions about agricultural water use and efficiencies across the United States. An understanding of common irrigation technologies and the impacts of best management practices in irrigation may be useful to Congress concerning potential policy responses to this issue. As a major user of water, the agricultural industry's use of water resources continues to be a focal point of agriculture policy. Additional demands on water supplies, extreme weather events (e.g., prolonged drought), and agricultural market conditions have raised producers' interest in investing in irrigation systems. Increased pressure on the industry to reduce its water use has also drawn interest in the adoption of irrigation technologies and best management practices (BMPs) as a means of achieving efficiency and potential water savings.
The federal government performs several roles in assisting agricultural producers with irrigation practices, including financial assistance, technical assistance, research, and monitoring and reporting. The majority of financial and technical assistance is offered through voluntary conservation programs that target increased irrigation efficiency. In some cases, improvements in irrigation efficiency can increase water consumption because farmers increase the number of irrigated acres or grow more profitable, water-intensive crops. This raises questions about how and where federal funds are allocated, particularly in areas where water shortages are a concern.
The use and significance of irrigated agriculture varies widely across the United States. Although policy discussions related to irrigation typically focus on western states—home to roughly 71% of irrigated farms—irrigation is practiced in all 50 states and is growing in the east. Over time, there has been a shift in water resources used for irrigation, with an increasing reliance on groundwater and less on the use of surface water.
The type of irrigation system used has also shifted over time—from a gravity, or flood-type of irrigation, to potentially more efficient pressurized sprinkler and drip irrigation systems. Pressure systems account for between 58 to 65% of irrigation systems used in the United States and include applicators such as center pivot, surface drip, slide roll or wheel move, and micro sprinkler. Gravity flow, which includes furrow, and controlled and uncontrolled flooding, accounts for approximately 35 to 42% of irrigation systems in the United States. Irrigation BMPs center around how water is managed on a farm and includes on-farm conveyance, irrigation scheduling, and application methods. Increasingly, precision technologies (e.g., drones, sensor networks, data analytics, etc.) are becoming a common part of many irrigation systems because of their potential to increase efficiencies and reduce costs.
The use of irrigation technology and BMPs bring both benefits and costs. The control of water application achieved through irrigation systems can create higher yields and allow the production of higher value crops, while potentially reducing some production costs. The additional cost of installing and maintaining these systems, however, can present a barrier to implementing BMPs. Accounting for variations in the local climate, soil type, water quality, and water availability may also challenge adoption of irrigation technologies and BMPs.