Storing Water for the Environment: Operating Reservoirs to Improve California’s Freshwater Ecosystems

Public Policy Institute of California (PPIC) | August 23rd, 2022

Large reservoirs like those that rim the Central Valley are essential for managing water in California’s highly variable climate. They provide multiple benefits includi

Large reservoirs like those that rim the Central Valley are essential for managing water in California’s highly variable climate. They provide multiple benefits including water supply, hydropower, flood management, and recreation. However, construction and operation of these reservoirs have also imposed significant environmental costs, including native fishes’ loss of access to high-quality habitat above dams and degradation of freshwater ecosystems below them. Moreover, regulatory uncertainty for water users is rising as these ecosystems decline. California needs a new approach for managing environmental water in its large reservoirs, particularly as the climate warms and droughts become more intense.

Surface Storage - CalFed (Resource Management Strategy)

California Department of Water Resources (DWR) | July 29th, 2016

California remains significantly dependent upon surface water. A review of the California Water Balance Summary, 2001-2010 (California Water Plan Update 2013, Volume 1, C

California remains significantly dependent upon surface water. A review of the California Water Balance Summary, 2001-2010 (California Water Plan Update 2013, Volume 1, Chapter 3, Table 3-2), indicates that in an average year like 2010, about 65 maf (million acre-feet) (more than 80 percent) of 80 maf total dedicated and developed water supply is associated with surface water. Surface storage is an essential element of managing the state’s surface water resources. The naturally arid conditions found in much of California, coupled with seasonal variations of too much or too little water prompted water planners of the past to implement conveyance and storage projects to support land development, population, and economic growth. After construction, these dams captured seasonal runoff and stored it for beneficial uses during drier times. Today, these projects facilitate a larger set of water management objectives including reliable water supplies, water quality and ecosystem maintenance, flood management, and hydropower generation. In many areas of the state, surface water and groundwater are used conjunctively. Coordinated surface water and groundwater management can be either formal or informal. For example, a managed groundwater recharge program where surface water is infiltrated to an aquifer for later use is formal; excess applied surface water in agricultural areas during wetter years that increases the availability of groundwater in drier years is often more informal. Dams and surface water storage continue to be a critical tool for providing water management flexibility in California. The amount of surface water in California, as noted above, often make it a foundational integration element of more diverse local and regional water management portfolios. In addition to storing water for use by residents, businesses, and industries, these facilities provide vital supplies during warm and dry periods for growing crops and maintaining the state’s managed wildlife refuges.

Temporary Urgency Change Petition for February 1, 2023, through March 31, 2023

California State Water Resources Control Board (SWRCB) | February 13th, 2023

The Complete Story of the Project: Its Purposes, Plans, and Progress of Construction

Scientific American | September 1st, 1932

IN THE Black Canyon of the Colorado, where the river forms the boundary between the states of Arizona and Nevada, the Government of the United States through the Depa

IN THE Black Canyon of the Colorado, where the river forms the boundary between the states of Arizona and Nevada, the Government of the United States through the Department of the Interior and directly by the Bureau of Reclamation has started construction of Hoover Dam. On September 17, 1930, constructional activities were formally inaugurated by Secretary of the Interior Ray Lyman Wilbur, and since that date, under the supervision and control of the Bureau of Reclamation, headed by Commissioner Elwood Mead, the building of the dam has progressed rapidly. Construction operations are carried out under the direction of R. F. Walter, Chief Engineer of the Bureau of Reclamation, represented in the field by the writer.

The Economic Value of Carryover Storage in California’s Water Supply System with Limited Hydrologic Foresight

University of California, Davis (UC Davis) | July 1st, 2021

The security and prosperity of California’s economy depend on a large, interconnected and highly engineered water supply system with vast surface and groundwater stora

The security and prosperity of California’s economy depend on a large, interconnected and highly engineered water supply system with vast surface and groundwater storage operated for over-year storage. Substantial public investment is needed to maintain and improve these systems with changing climate risks, increasing demands, and aging infrastructure. Hydro-economic optimization identifies promising opportunities for managing such systems, but scientific and engineering advances are needed to better incorporate hydrologic uncertainty and conjunctive management of streams and aquifers into such models. Over two decades of research the California Value Integrated Network (CALVIN) linear programming hydro-economic model has yielded insights for California’s inter-regional water system on many fronts, including climate change, groundwater sustainability, conjunctive management in southern California, water markets, and reservoir operations in Northern California. Yet there remains unrealized potential to improve the model’s formulation to better represent inter-annual hydrologic variability while concurrently developing reservoir control rules. To address this gap, this study implements linearized quadratic carryover storage value functions on 26 surface reservoirs and linear groundwater storage penalties on 32 groundwater reservoirs to optimize California’s inter-regional water system seasonal and inter-annual operations with limited seasonal foresight. A convex Pareto front tradeoff between total system cost and groundwater overdraft is developed through multi-objective evolutionary optimization of inter-annual carryover storage penalties. Resulting over-year storage valuations span a wide range of nearoptimal reservoir operations, suggesting substantial system flexibility and adaptability when managed in an integrated way. Generalized relationships between carryover capacity, carryover use, and the marginal value of carryover storage are drawn for the multi-reservoir system. When compared to carryover operations based on California’s current simulation model, CalSim-II, the performance of these near-optimal reservoir operations suggests room to improve currently prescribed reservoir control rules, especially in supporting more  sustainable conjunctive management with aquifers. Overall, this study demonstrates the practicability, feasibility, and utility for understanding large-scale integrated multi-reservoir conjunctive use systems using limited foresight with explicit carryover storage values.

The Radical Groundwater Storage Test

Scientific American | October 19th, 2017

IN BRIEF California could better survive flood years and drought years by capturing floodwaters and using them to recharge underground aquifers that farmers and muni

IN BRIEF California could better survive flood years and drought years by capturing floodwaters and using them to recharge underground aquifers that farmers and municipalities now pump from when rains are scarce. To do so, water users and managers have to regard surface water and groundwater as one connected resource. A variety of test projects are proving that this approach can work. For example, farm fields can be flooded even when crops are growing so the water can percolate down into aquifers. Revising water rights and paying landowners to allow flooding can help the techniques work across California and the world.

The Role of Snowpack, Rainfall, and Reservoirs in Buffering California Against Drought Effects

U.S. Geological Survey (USGS) | August 1st, 2016

California’s vast reservoir system, fed by annual snow and rainfall, plays an important part in providing water to the State’s human and wildlife population. There ar

California’s vast reservoir system, fed by annual snow and rainfall, plays an important part in providing water to the State’s human and wildlife population. There are almost 1,300 reservoirs throughout the State, but only approximately 200 of them are considered storage reservoirs, and many of the larger ones are critical components of the Federal Central Valley Project and California State Water Project. Storage reservoirs, such as the ones shown in figure 1, capture winter precipitation for use in California’s dry summer months. In addition to engineered reservoir storage, California also depends on water “stored” in the statewide snowpack, which slowly melts during the course of the summer, to augment the State’s water supply.

The water footprint of water conservation using shade balls in California

Nature Portfolio (Springer Nature) | July 16th, 2018

The interest in quick technologic fixes to complex water problems increases during extreme hydroclimatic events. However, past evidence shows that such fixes might be ass

The interest in quick technologic fixes to complex water problems increases during extreme hydroclimatic events. However, past evidence shows that such fixes might be associated with unintended consequences. We revisit the idea of using shade balls in the Los Angeles reservoir to reduce evaporation during the recent drought in California, and question its sustainability by revealing the water footprint of this technologic water conservation solution.

Upper San Joaquin River Basin Storage Investigation (Temperance Flat)

U.S. Bureau of Reclamation (USBR) | April 1st, 2016

The Upper San Joaquin River Basin Storage Investigation is a feasibility study of new surface water storage that is being performed by the U.S. Department of the Interior

The Upper San Joaquin River Basin Storage Investigation is a feasibility study of new surface water storage that is being performed by the U.S. Department of the Interior’s Bureau of Reclamation. The purpose of the investigation is to determine the type and extent of federal, state, and regional interests in a potential dam project in the upper San Joaquin River watershed to expand water storage capacity; improve water supply reliability and flexibility for agricultural, urban, and environmental uses; and enhance San Joaquin River water temperature and flow conditions to support anadromous fish restoration efforts This investigation is one of five surface water storage studies recommended in the CALFED Bay-Delta Program Programmatic Environmental Impact Statement/Report Record of Decision of August 2000. Reclamation released a Draft Feasibility Report in February 2014 that provides an in depth examination into the potential construction of a new dam and reservoir on the upper San Joaquin River, between Friant and Kerckhoff dams. View the feasibility report available here. Reclamation released a Draft Environmental Impact Statement for the Upper San Joaquin River Basin Storage Investigation for public comment on September 5, 2014. Written comments may be provided at any time on or before Oct. 27, 2014. Testimony can also be submitted at the upcoming public hearings on October 14 and October 16, 2014. Comments and testimony will be considered in the Final EIS. The Draft EIS documents the potential environmental effects of alternatives to increase storage of water from the upper San Joaquin River watershed to improve water supply reliability and operational flexibility in Central Valley Project San Joaquin Valley areas and other regions of California, and to enhance water temperature and flow conditions in the San Joaquin River downstream from Friant Dam for salmon and other native fish. In addition to the No Action Alternative, the Draft EIS documents five action alternatives that include constructing a dam in the upstream portion of Millerton Lake at river mile 274. The action alternatives vary based on operations and intake feature configurations. The Draft EIS was prepared for formal public review and comment, consistent with the National Environmental Policy Act. View the Draft EIS report available here.Upper San Joaquin River Basin Storage Investigation

Water Partnerships between Cities and Farms in Southern California and the San Joaquin Valley

Public Policy Institute of California (PPIC) | October 29th, 2020

The San Joaquin Valley and urban Southern California are worlds apart in many ways. Yet each face growing water challenges and a shared interest in ensuring reliable, aff

The San Joaquin Valley and urban Southern California are worlds apart in many ways. Yet each face growing water challenges and a shared interest in ensuring reliable, affordable water supplies to safeguard their people and economies. Both regions’ water futures could be more secure if they take advantage of shared water infrastructure to jointly develop and manage some water supplies.  Increasing climate volatility is heightening concerns about droughts of the future. And two major shifts in California’s water landscape have generated new opportunities for collaboration between urban and agricultural interests. For urban areas, significant declines in water demand have reduced pressure on supplies during normal and wet years for many agencies, making reliability for future droughts the primary concern. For the overdrafted San Joaquin Valley, the requirement to manage groundwater sustainably has heightened interest in expanding water supplies and underground storage.  Partnerships between Southern California cities and San Joaquin Valley farms could help alleviate groundwater overdraft in the valley while building drought resilience in Southern California. More flexible supplies can help agencies adapt to changing conditions. By coordinating the location of infrastructure investments, agencies can use partnerships to bring the water where and when it is most needed, at least cost.  This report explores a variety of solutions that could benefit both regions. For the San Joaquin Valley, we look for ways to augment water supplies to ease the transition to groundwater sustainability, while for Southern California we explore options that would increase cities’ ability to deal effectively with extended droughts. By diversifying water supplies, building connections to share water more flexibly, and preparing for the extreme events to come, such partnerships would support Governor Newsom’s Water Resilience Portfolio, and pave the way for a shared effort to make the state’s water system more resilient to a changing climate.