Presentations 2016

The Yakima basin in south-central Washington is a major contributor to irrigated agricultural production in the State’s 40 billion dollar agricultural industry. Climate change forecasts suggest that the snowpack providing water for the basin is expected to diminish in the next decade, bringing more frequent and more severe agricultural irrigation water curtailment to several major irrigation districts in the basin. The economic impact of the 2015 drought on Washington State Agriculture has been estimated by the state to be around $1 billion, including direct and indirect economic impacts. There are many drought mitigation strategies that can be pursued at either the individual farm or irrigation district level including crop choice, the use of holding ponds, water market leasing, and emergency groundwater use for those who have invested in emergency wells. These wells may only be used with permission from the Washington State Department of Ecology during a formal State-recognized drought emergency. To the extent that these emergency groundwater wells reduce agricultural losses to the farmers using them, they will reduce the aggregate economic impacts. The economic benefits of groundwater use would be attenuated, however, if their use has downstream consequences on other surface water users through surface-groundwater interaction, or through impacts on other groundwater users during the high-demand season of late summer. Several recent studies have estimated the economic impact of drought in the Yakima Basin, but no study to date has estimated the value of emergency groundwater pumping in the basin. The objective of this study is to take a first step toward accurately estimating the value of emergency groundwater pumping in terms of its effect in reducing economic impact of drought. This analysis uses an existing hydrologic model of the Yakima Basin based on RiverWare, agricultural crop distributions and water value data for the major proratable irrigation districts in the Basin, and newly compiled emergency well-log data from these districts for the drought years of 2001, 2005, and 2015. We will also use curtailment histories for the Yakima Basin Project (a US Bureau of Reclamation Irrigation Project) as well as simulated curtailment distributions based on available CMIP3 climate scenarios to estimate the aggregate expected present value of emergency pumping in terms of economic loss reduction. While we are not yet able to estimate the indirect effects of emergency pumping on other users, this model will ultimately be integrated with a groundwater model of the Basin, which will allow us to estimate these effects. We also empirically examine which water rights holders use emergency wells and which do not to assess the importance of spatial location, terrain, soil type, and farm size.