California Central Valley Water Rights in a Changing Climate

Abstract

Climate change and resulting changes in hydrology are already altering-and are expected in the future to continue to alter-the timing and amount of water flowing through rivers and streams. As these changes occur, the historical reliability of existing water rights will change. This study evaluates future water rights reliability in the Sacramento-Feather-American river watersheds. Because adequate data are not available to conduct a comprehensive analysis of water rights reliability, a condition placed into certain water rights, known as Term 91, is used to model projected water rights curtailment actions. Comparing the frequency and length of the historical and simulated future water diversion curtailments provides a useful projection of water rights reliability and water scarcity in the Sacramento-San Joaquin Delta (Delta) watershed.Projections of future water rights curtailments show that water rights holders are likely to be curtailed much more frequently, and for significantly longer durations, as we move through the 21st century. Further, many more water rights holders will be affected by curtailment actions in the future. As curtailments last longer and become more common, more water users will have to access other supplies, such as groundwater or water transfers, or will have to fallow land or conserve water in other ways to meet their demands. These activities will likely ratchet up the potential for additional conflicts over water in the Delta watershed.

Challenges and Proposals for Socio-Ecological Sustainability of the Tagus–Segura Aqueduct (Spain) under Climate Change

“…Of the five main water sources that supply this area (the Los Angeles Aqueduct, Colorado River, California Aqueduct, local groundwater, and reclaimed water) most will be impacted by climate change, water quality, energy, and cost constraints [20]. Similar consequences and the implications of climate change were argued in Reference [14] in California in relation to water dependence under IBWT. Similar implications can be shown to exist in the study case (south-east of Spain).…”

“…Snaddon et al [12] identified more than 100 transfers in nearly 30 countries, most of which have been completed and commissioned. Ghassemi and White [13] counted more than 50 (including finished projects and proposals) in just five countries (USA, Australia, Canada, China and India), of which initiatives such as the Central Valley Project planned in 1933 in California (USA) to provide water for irrigation and supply in the Central Valley of California [14], the Snowy Mountains Scheme (Australia) [15], and China's South-North Water Transfer Project (SNWT) [2], the world's largest transfer, are of great significance.…”

Effects of the Structure of Water Rights on Agricultural Production During Drought: A Spatiotemporal Analysis of California's Central Valley

“…The persistent drought conditions significantly strained agricultural production throughout the valley with an estimated economic cost of $2.7 billion in 2015 alone (Howitt et al, ). Research suggests that future changes in climate will continue to impact surface water availability, ultimately affecting plant growth rates as well as irrigation timing and runoff (Mann & Gleick, ; Schwarz, ). These changes will likely increase legal mandates curtailing surface water use.…”

“…These changes will likely increase legal mandates curtailing surface water use. In a study of the Sacramento‐San Joaquin Delta, Schwarz () estimates that water rights curtailments between 2030 and 2059 may last 20% longer and occur with 10% greater frequency than they have in the past. These changes, coupled with rapidly increasing population growth and shifts in agricultural demand will place significant strain on agricultural systems in the Central Valley in the future, threatening national food security.…”

Climate change effects on water allocations with season dependent water rights

“…We identified one study that considered climate change alterations to water allocations based on water rights. Schwartz evaluated the frequency and duration of shortages to junior water right holders with historical drought periods and climate-driven future simulations using California's State Water Project to assess water reliability (Schwarz 2015). Duration of future shortages is anticipated to become longer and more frequent, potentially exacerbating groundwater overdraft, subjecting more water right holders to shortages, incentivizing water transfers to reallocate water among users, and increasing reliance on stored water, when available.…”