Institutions and the Economic Efficiency of Managed Aquifer Recharge as a Mitigation Strategy Against Drought Impacts on Irrigated Agriculture in California

American Geophysical Union (AGU) | May 28th, 2022

Managed aquifer recharge (or intentional recharge) is a purposeful human intervention designed to supplement natural enrichment processes of groundwater aquifers by vario

Managed aquifer recharge (or intentional recharge) is a purposeful human intervention designed to supplement natural enrichment processes of groundwater aquifers by various methods. It holds the potential to mitigate the impact of climate uncertainty on irrigated agriculture by restoring storage levels in depleted aquifers, the economic value of which increases during droughts. We use a high-resolution dynamic regional hydroeconomic framework that endogenizes farming decisions in response to water quantity-quality changes, as well as complex hydrogeological principles to analyze several institutional designs and climate scenarios applied to the Kings Groundwater Basin in California. Our analysis demonstrates that intentional recharge is of high benefit to the region, potentially increasing average groundwater levels in the region by 20% over a 20 year horizon. Additionally, we show how this practice could become the subject of second-best arrangements among water users in the region in view of property rights to groundwater derived from recent legislation in California, thus increasing its materialization potential. However, we also find that the quantity recharged is sensitive to climate conditions and hydrological properties.

Integrated Water Resources Plan 2015 Update

Metropolitan Water District of Southern California (MWD) | January 1st, 2016

In California water, uncertainty comes with the territory. Being unprepared for tomorrow, however, is simply not an option. The Metropolitan Water District of Southern C

In California water, uncertainty comes with the territory. Being unprepared for tomorrow, however, is simply not an option. The Metropolitan Water District of Southern California prepares for tomorrow with an evolving long-term water strategy known as its Integrated Water Resources Plan, or IRP. The inaugural IRP was adopted in 1996, with updates in 2004 and 2010. The 2015 IRP Update continues the tradition of assessing and adapting to changing conditions facing Southern California. The fundamental goal of the IRP is for Southern California to have as reliable a water system for tomorrow as the region has enjoyed for decades, regardless of the challenges that emerge along the way. Metropolitan plans to meet this goal through an adaptive management strategy that is the cornerstone of the 2015 IRP Update. Metropolitan was authorized by the California Legislature in 1928 to advance a regional approach to water supply in Southern California. Metropolitan’s initial mission was to construct the 242-mile Colorado River Aqueduct to its service area on the Southern California coastal plain. Metropolitan’s service area had an assessed property valuation of approximately $2 billion at the time. Now Metropolitan serves a six-county service area with a property valuation of approximately $2 trillion. Metropolitan imports supplies from both the Colorado River and Northern California via the State Water Project while investing in a variety of storage, local supply and conservation initiatives. Metropolitan has a long record of promoting alternatives to imported water supplies, dating back to the 1980s. With the IRP, that process became more formalized as a long-term strategy and official policy. Metropolitan has steadily diversified the future water portfolio for Southern California with each revision to the IRP. This update is no exception. Investments to maintain the reliability of imported supplies are complemented by an expansion of local supply development along with a reduction in demand through a variety of conservation and water-use efficiency initiatives. The necessary suite of actions evolves over time based on the water conditions of tomorrow. Updating the IRP creates a new baseline for managing into the future.

Integrating Storage in California’s Changing Water System

University of California, Davis (UC Davis) | November 13th, 2014

Surface water reservoirs provide water supply and flood management benefits by capturing water when available and storing it for use when needed. Surface reservoirs are c

Surface water reservoirs provide water supply and flood management benefits by capturing water when available and storing it for use when needed. Surface reservoirs are commonly operated more for seasonal or short-term inter-annual needs. Groundwater aquifers generally provide longer-term storage and a source of water and seasonal storage in areas where surface water is limited. This paper reviews the benefits and challenges of water storage in California’s evolving water system, and provides some quantitative insights from an integrated analysis of this system. Water storage should not be viewed as isolated projects. For today’s water management objectives and conditions, surface water and groundwater storage should be considered and analyzed as parts of larger systems or portfolios of actions that include a wide variety of water sources, types and locations of storage, conveyance alternatives, and managing all forms of water demands. Such an integrated, multi-benefit perspective and analysis is a fundamental departure from most ongoing policy discussions and project analyses. The pilot study described in this paper focused on water storage and concludes that ability to utilize additional water storage in California varies greatly with its location, the availability of water conveyance capacity, and operation of the system to integrate surface, groundwater, and conveyance facilities. At most, California’s large-scale water system could utilize up to 5-6 million acre-feet of additional surface and groundwater storage capacity, and probably no more, which would likely provide 50-150 taf/year of additional water delivery for each million acre foot of additional storage capacity alone. The water supply and environmental performance of additional storage capacity is greatest when surface and groundwater storage are operated together. The benefits, and likely cost-effectiveness, of coordinating surface and groundwater storage and conveyance operations greatly surpass the benefits of expanding storage capacity alone, greatly expanding water delivery increases to as much as 200 taf/maf of additional storage capacity. Because we did not quantify and compare the economic value and costs of water supply and other benefits of expanding storage capacity, we cannot yet say if particular expansions would be economically justified. Similarly, because we did not comprehensively analyze the environmental impacts of expanding storage capacity or specific storage projects, we cannot yet say if particular expansions would be environmentally justified. Further, this study does not consider reoperation of existing facilities, water demand management, changes in prioritization of water uses or rights, or other policy or regulatory actions that might change the ability to supply water demands using existing water storage capabilities.

Isolating the Poroelastic Response of the Groundwater System in InSAR Data From the Central Valley of California

American Geophysical Union (AGU) | April 28th, 2023

Kern Water Bank Status Report No. 3

California Department of Water Resources (DWR) | April 1st, 1990

LADWP Stormwater Capture Master Plan

Los Angeles Department of Water & Power (LADWP) | October 5th, 2015

To ensure a safe and reliable water supply for future generations of Angelenos, one of the City’s key strategies is to increase the local water supply and decrease the

To ensure a safe and reliable water supply for future generations of Angelenos, one of the City’s key strategies is to increase the local water supply and decrease the need to purchase imported water. However, in large part due to urbanization, the majority of precipitation that falls onto the City flows into storm drains and out to the ocean. In light of these conditions, stormwater is an increasingly viable supply. Capturing and using stormwater on-site can offset potable water demand. Capturing and infiltrating stormwater into subsurface groundwater aquifers increases local groundwater reserves. Both infiltration and capture for direct use enhance the reliability of the City’s water supply. Projects to capture and conserve stormwater runoff comprise an important component of the City’s water supply portfolio. The City is a part of a complex multi-jurisdictional region. As such, implementing effective and comprehensive local stormwater capture projects involves a collaborative effort between several agencies including LADWP, the Los Angeles County Flood Control District (LACFCD), the Los Angeles Bureau of Sanitation (LASAN), the Los Angeles Bureau of Street Services (LABSS), the Los Angeles Bureau of Engineering (LABOE), and the US Army Corps of Engineers (USACE). Additionally, LADWP partners with many community-based organizations to leverage their relationships with the residents of the City. Working together on projects that have multi-benefits for multiple agencies allows for the opportunity to cost-share and reduces the financial burden.

Land subsidence in the San Joaquin Valley, California, as of 1972

U.S. Geological Survey (USGS) | July 10th, 1975

Land subsidence which began in the mid-1920's due to groundwater overdraft in the San Joaquin Valley has caused widespread concern for the past two decades. Withdrawals

Land subsidence which began in the mid-1920's due to groundwater overdraft in the San Joaquin Valley has caused widespread concern for the past two decades. Withdrawals for irrigation increased from 3 million acre-feet in 1942 to 10 million acre-feet in 1966. Water levels declined at unprecedented rates during the 1950's and early 1960's. Pumping lifts became inordinately high, well casings failed at alarming rates, and differential settlement caused numerous farming and engineering problems. By 1970,5,200 square miles of valley land had been affected, and maximum subsidence exceeded 28 feet. The valley-wide volume of subsidence totaled 15.6 million acre-feet, one-half the initial storage capacity of Lake Mead. This subsidence represents one of the great environmental changes imposed by man. Importation of surface water to the northwestern and eastern areas of overdraft in the valley began in the 1950's and to the much larger western and southern areas in the late 1960's. Canal imports have largely replaced ground-water pumpage in these areas. As of 1973, after three decades of continued declining water levels, many hundreds of irrigation wells are idle and water levels are rising. Throughout much of the valley, artesian pressures are recovering toward their presubsidence levels, and elevations of the subsiding land surface are stabilizing. Basic-data graphs and computer-plotted stress-strain relationships constitute a major part of this report. They are based on 10-13 years of detailed field measurements of both water-level change and compaction collected by the U.S. Geological Survey at 20 selected locations in the San Joaquin Valley. The recharge characteristics of a ground-water reservoir are indicated roughly by the volume ratio, which is subsidence/pumpage. In the Los Banos-Kettleman City area, the values of this ratio range from less than 0.2 near the perimeter to more than 0.6 in the central part of the area. In the corresponding parts of the Arvin-Maricopa area, the ratio ranges from near 0 to more than 0.4.

Los Angeles Basin Stormwater Conservation Study: Plan of Study

U.S. Bureau of Reclamation (USBR) | February 28th, 2013

Imported water supplies to Los Angeles County, California, are uncertain due to periodic droughts in northern California and the Colorado River Basin, court decisions r

Imported water supplies to Los Angeles County, California, are uncertain due to periodic droughts in northern California and the Colorado River Basin, court decisions related to endangered species in the Bay Delta, and potential allocations of Colorado River water. Changing demographics, climate variability, and the competing interest for available water present additional long-term risks to the stability and reliability of imported water. Accordingly, various Los Angeles area agencies with water management authority, such as the Los Angeles County Flood Control District (LACFCD), are actively pursuing a strategy aimed at achieving water independence by developing local water resources such as stormwater. The LACFCD is the primary agency for conducting groundwater replenishment operations in Los Angeles County. In typical years, the LACFCD infiltrates more than 270,000 acre-feet of captured stormwater, imported water, and recycled water into the various groundwater basins in Los Angeles County. In wetter years, that number can exceed 700,000 acre-feet and, in drier years, may be little more than 150,000 acre-feet. LACFCD partnered with the U.S. Department of the Interior, Bureau of Reclamation’s (Reclamation) Southern California Area Office to study long-term flood control and water conservation impacts from projected population and climate conditions. The Los Angeles Basin Stormwater Conservation Study (Basin Study) will recommend potential changes to the operation of stormwater capture systems, modifications to existing facilities, and development of new facilities that could help resolve future flood control and water supply issues. The Los Angeles River, San Gabriel River, Ballona Creek, South Santa Monica Bay, North Santa Monica Bay, and Dominguez Channel/Los Angeles Harbor watersheds (Watersheds) are the focus of this Basin Study (figure 1). This study incorporates the entire watershed boundaries, including where they extend outside Los Angeles County. The Watersheds share attributes such as overlapping municipal and water agency boundaries, an interconnected flood control system, and a common planning purpose with major ongoing planning efforts like the Greater Los Angeles County Integrated Regional Water Management Plan (IRWMP), Gateway IRWMP and the Metropolitan Water District Integrated Resources Plan. Related links: Los Angeles Basin Study Summary Report Task 2: Water Supply and Demand Analysis Click here for Reclamation's index of inter-related LA Basin Study reports and appendices.

Los Angeles Basin Stormwater Conservation Study: Task 2 Water Supply & Water Demand Projections

U.S. Bureau of Reclamation (USBR) | December 1st, 2014

The Los Angeles County Flood Control District (LACFCD) partnered with the U.S. Department of the Interior, Bureau of Reclamation (Reclamation) to collaborate on t

The Los Angeles County Flood Control District (LACFCD) partnered with the U.S. Department of the Interior, Bureau of Reclamation (Reclamation) to collaborate on the Los Angeles Basin Stormwater Conservation Study (LA Basin Study). The purpose of the LA Basin Study is to study long-term water conservation and flood control impacts from projected climate conditions and population changes in the Los Angeles Basin. The LA Basin Study will recommend potential changes to the operation of stormwater capture systems, modifications to existing facilities, and development of new facilities that could help resolve future water supply and flood control issues. The recommendations will be developed through identifying alternatives and conducting trade-off analyses. For Task 2 of the LA Basin Study, Water Supply and Water Demand Projections, existing and projected water supplies and demands were characterized for the LA Basin Study Area (Study Area) out to 2095, with consideration of projected climate change effects. It is important to note that this Task 2 report inventories projected available supplies (i.e., potential supplies), and does not make assumptions for the volume of each supply source that will actually be used to meet projected demands, nor the facilities necessary to access and serve those supplies. This determination would require more in-depth integrated supply and demand planning to predict and analyze the multitude of factors that influence water supply and use decisions such as policy, cost, environmental factors, reliability, etc. This Task 2 report is intended to provide a supply and demand basis for understanding the potential need and benefit of additional stormwater capture systems that could be implemented across the region by the LACFCD and its partners. Given that stormwater is a local and relatively inexpensive source of supply, it must be a critical and substantial part of the LA Basin water supply portfolio that could help meet demands through 2095 and beyond.

Los Angeles Basin Study Summary Report

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

Changing demographics, climate change, and competing interests for available water supplies all present long-term risks to the stability and reliability of the region’s

Changing demographics, climate change, and competing interests for available water supplies all present long-term risks to the stability and reliability of the region’s imported water.  The region recognizes that today’s challenges require an integrated water resources management approach. For decades, this region has operated and maintained one of the most effective flood control systems in the world that protects millions of people from the impacts of flooding in the region. This system sends much of the stormwater runoff into the ocean, water that historically recharged local groundwater basins, making this region even more dependent on imported water supplies. As regulatory pressure to clean up polluted stormwater runoff continues and imported water resources diminish, this local source of water supply is becoming more and more attractive (GLAC IRWMP 2014). Many of the region’s water management agencies have studied and planned for increasing use of local recycled and graywater supplies, ocean and brackish desalination, developing more groundwater, and implementing improved water conservation initiatives to extend existing supplies. Additionally, social trends and concerns also drive the emphasis on the use of local water supplies. However, the one major local resource that has not been studied in-depth is stormwater and its opportunities to optimize the reliability of local supplies. To enhance the capabilities of the existing stormwater conservation infrastructure within the Los Angeles Basin, the LACFCD began to investigate long-term projected needs and future climate conditions within the region. Given that local groundwater plays such a vital role in the region’s water supply portfolio, detailed scientific, engineering, and economic analyses were conducted to identify strategies for enhancing stormwater capture for groundwater recharge. The LA Basin Study examined the region’s water supplies and demand, and impacts from projected population growth and changing climate in the watersheds of the Los Angeles region. The objectives of the study were to: • Use state-of-the-art climate change analysis to develop projections of future water supply and demands in the Basin. • Analyze how the Basin’s existing water infrastructure and its operations will perform in the face of changing water realities. • Develop and highlight opportunities to adapt to current and future water demands. • Conduct a trade-off analysis of identified opportunities. Concepts ranged from enhancing the existing stormwater capture system and modifying existing facilities (including those capturing runoff for groundwater recharge), to developing new structural and nonstructural concepts that could help resolve future water supply and flood risk issues. This Summary Report presents highlights of the critical tasks associated with this Basin Study and the results and findings produced throughout this collaborative study effort. Full study chapters and appendices: Plan of Study Fact Sheet Task 2: Water Supply and Demand Task 3: Climate Change Analysis Task 3.1: Development of Climate-Adjusted Hydrologic Model Inputs Task 3.1:  Climate Change and Hydrologic Projections Appendices Task 3.2:  Hydrologic Modeling Report Task 3.2: Annual Hydrologic Results Workbook Task 4: Existing Infrastructure Response & Operations Guidelines Analysis Final Report Task 5: Task 5 - Infrastructure & Operations Concept Analysis Final Report Task 6: Trade-off Analysis Final Report Click here for Reclamation's full index  including public outreach and webinars