The U.S. Department of the Interior has tasked Reclamation with assessing the potential impacts of climate change during the 21st century and how these changes might impact water operations, hydropower, flood control, and fish and wildlife in the western United States. The Mid-Pacific Region is coordinating several different studies that will assess risks to future water supplies across its river basins and water projects, while analyzing a wide range of adaption and mitigation strategies.
Sacramento and San Joaquin Basins Study
During 2013, the Region completed a comprehensive Climate Impact Assessment, which was the first phase of the Sacramento and San Joaquin Basins Study. The assessment evaluated climate impacts to water supplies and demands throughout the basins. Findings in this assessment included increases in mean annual temperatures under several future climate scenarios by up to 6 degrees Fahrenheit by the end of the 21st century throughout California’s Central Valley. It also forecast a decline of up to 5 percent in precipitation in the northern half of the valley and up to 10 percent in the southern portion.
The purpose of the Sacramento and San Joaquin Basins Study, begun in November 2012 and projected to be completed by November 2014, is to conduct a comprehensive assessment of the effects of future changes in climate on water supply and demand. The basins study will perform a system risk and reliability assessment of the baseline system, which includes identification of current and future imbalances in water supplies and demands under different potential future conditions.
As the basins study nears completion, the comprehensive set of adaptation and mitigation strategies will include those proposed by study partners and stakeholders during public meetings.
Klamath Basin Study
The Region’s work on the study in 2013 included extensive research on the area and development of a water supply assessment, reviewed by the study’s Technical Working Group and by external reviewers from the U.S. Army Corps of Engineers, Oregon Climate Change Research Institute and the U.S. Geological Survey.
In 2014, the study team will begin a system reliability analysis, which will be followed by an outreach process to identify potential climate adaptation strategies to be considered in the study.
Truckee Basin Study
During 2013, the Region’s work on this basin study included meeting with the public agencies in the Truckee Basin that have water management or land-use planning authority. The meetings determined how agencies view future growth and water demands in their jurisdictions.
Based on these meetings, the study team, along with the major study partners and stakeholders, prepared three socio-economic projections or “storylines,” which are scenario-based narrative descriptions of projected future conditions in the Truckee Basin, out to the year 2100. The scenarios are being used to estimate water supplies and a potential range of future water demands. During 2013, work was also initiated on a specialized investigation to assess potential climate changes to flood frequency and volumes in the Truckee River. This flood investigation will be completed by 2014.
Central Valley Project Integrated Resource Plan
During 2013, the Region completed a long-range planning study which investigated potential climate change impacts on water supplies and demands for the Central Valley Project. This study also performed an exploratory analysis of potential climate adaptation strategies to address impacts.
The study employed a scenario-based planning approach by combining socioeconomic and projected climate futures from socioeconomic-climate scenarios, characterizing a wide range of 21st century uncertainties. Existing hydrologic, operational, water quality, hydropower, urban, and economic models were integrated into a suite of analytical tools and used to evaluate a wide range of potential impacts.
The study also simulated several portfolios of system-wide and local water management actions, including water conservation, storage, conveyance, and environmental flows that might potentially be employed to adapt to 21st century challenges. These adaptation strategies were evaluated in an exploratory manner against key CVP performance criteria to assess their potential effectiveness under the broad range of future uncertainties represented in the socioeconomic-climate scenarios, and to identify tradeoffs among the strategies for various water supply, urban and agricultural demand, water quality, environmental, hydropower, and urban and agricultural economic performance metrics.
The study results and models are currently being used to provide information and modeling capabilities to the Sacramento-San Joaquin Basin Study. In addition, the study is providing important climate change information to other long-range planning activities being conducted by Reclamation and partner agencies.
During 2013, California has experienced historically low precipitation, resulting in minimal reservoir inflows and low water allocations; challenges in managing Delta salinity; and early increases in reservoir releases, which had led to low carryover storage into 2014.
In an effort to proactively address potential dry conditions into 2014, the Bureau of Reclamation’s Mid-Pacific Region held a series of meetings in 2013 with Central Valley Project water contractors, CVP power customers, Tribes, non-governmental organizations, other federal agencies, and state of California agencies to discuss the status of potential water management strategies in 2014. Customers and stakeholders were asked to provide ideas and suggestions for Reclamation’s consideration in developing strategies.
Following the individual meetings and receipt of the interested parties’ input, Reclamation developed a list of the suggested strategies and began holding group meetings, which gathered together individuals representing interests throughout the CVP. The goal of the meetings was to raise awareness about potential future conditions, facilitate open communication, and brainstorm water management considerations in the event conditions stay dry into 2014.
Due to the large number of actions and strategies included on the list and limited resources, Reclamation was unable to address each idea prior to the beginning of 2014. Although Reclamation has not committed to carry any particular action forward, the list of potential strategies will be aimed at minimizing negative impacts to affected CVP customers and stakeholders associated with a potential dry 2014 water year.
Since the 1970s, the Region has recognized the practice of transferring water from one water user to another through authorized legislation, secretarial directives, policy statements, transfer agreements, and water transfer guidelines.
Water transfers can be an effective incentive for improved water management, as well as a way to promote water conservation, particularly in drought years, as long as transfers are consistent with state and federal law.
The Region continues to facilitate transfers of both CVP and non-CVP water. The transfer of CVP water may occur as long as it is consistent with the Central Valley Project Improvement Act and the transfer of non-CVP water is consistent with California state law. Non-CVP water transfers requiring the use of federal facilities for conveyance and/or storage are supported through Warren Act contracts.
February 28, 2014