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KEY MESSAGES
5 A shift to sprinkler irrigation or the lining of canals can reduce seepage to groundwater; this seepage (aquifer recharge) may serve other purposes in the watershed such as maintaining streamflow during low flow periods, providing domestic and municipal water supply, and supporting downstream irrigators.
6 Changes from flood to sprinkler irrigation can lead to an increase in water consumption due to increased crop production and additional water use by junior water rights holders.
7 While some changes to irrigation practice influence water consumption, others alter the timing and location of water availability; understanding the difference is essential for effective management and planning.
8 There may be scenarios in which the benefits of conversion to sprinkler irrigation - diverting less water and leaving more water in the stream at the time of diversion - outweigh the risks and potential impacts of increased consumption and reduced aquifer recharge.
9 Consequences of changing irrigation methods differ from place to place based on site-specific factors such as land and soil characteristics, crop type, water management context, and individual decision-making. Place-based strategies that consider these site-specific factors will be essential for supporting or enhancing irrigated agriculture while balancing the many other demands on water supply.
1 Irrigated agriculture is an essential part of Montana’s history, culture, and economy, and it contributes substantially to regional and national food security. Irrigated agriculture also represents the largest consumptive use of water in Montana and changes in irrigation practice can thus profoundly influence water supply and availability
2 Over the past 50 years, many producers across the West and in Montana have made changes to their irrigation practice and infrastructure in an effort to increase irrigation efficiency, defined as the ratio of water consumed by crops to diverted water (consumed water ÷ diverted water).
3 Changes in irrigation technology to increase irrigation efficiency, including shifts from flood to sprinkler irrigation or the lining of canals, can provide significant on-farm benefits such as reduced labor and increased production. Such changes may have positive or negative consequences for streamflow and aquatic ecosystems and the difference depends on local site-specific hydrologic and geologic conditions and irrigation management decisions.
4 Changes in irrigation technology that increase irrigation efficiency have not necessarily led to water conservation, and such changes may have unintended consequences for water supply and availability at a watershed scale.
10 Transparent measurement and monitoring of irrigation water, and the development of quantitative water budgets, will be essential in assessing hydrologic responses to changing irrigation methods and planning effectively for future water use.
11 The amount of water naturally stored in our watersheds is declining due to reductions in winter snowpack, floodplain disconnection, and shifts in irrigation methodology; irrigation infrastructure and management may offer opportunities for increased aquifer recharge and additional natural storage. Incentives are needed to support such opportunities.
12 Water policy can either support or constrain strategies to balance water supply and demand in response to shifting irrigation methods, population growth, and changes in climate; meaningful discourse is needed to assess key policies that can support creative win-win solutions for agriculture, aquatic ecosystems, and other essential water needs.
13 Agricultural decision-making is motivated by a broad spectrum of factors beyond profit maximization, including long-term operational viability, land management ethics, and maintenance of cultural identity. Policies, strategies, and incentive programs that consider the diversity of socio-cultural and economic motivators will be most effective.
14 Irrigation water management can, where desired, function as a tool to help communities achieve locally identified water objectives.
Table of Contents | Key Messages | Water and Irrigated Agriculture | Irrigated Agriculture in Montana | The Paradox of Irrigation Efficiency | Hydrology of Irrigated Agriculture | Assessing Consequences of Changing Irrigation Methods | Water Policy and Irrigated Agriculture | Adapting to Change | Conclusion | List of Contributors | Glossary | Footnotes | References