18.4: Water Infrastructure and Management

Managing and Moving Water Across California

The movement and storage of water in California are part of a complex and interconnected system that directly ties into the hydrologic cycle’s pools and fluxes (Figure 18.4.1). These systems, which store and transport water across diverse landscapes, are crucial for managing the state’s limited water resources. Without this extensive water infrastructure—including dams, reservoirs, aqueducts, and levees—California would not be able to support its current population or sustain its agricultural economy. This section examines the key components of California's water management systems, including the major projects that distribute water across the state, the challenges they face, and the efforts to maintain and improve these systems in the context of increasing climate variability and population growth. Video 18.4.1 further demonstrates the importance and size of some of California's water infrastructure projects.

Figure \(\PageIndex{1}\): "Water storage and distribution in California." ​​This work by Shannon1 via Wikimedia Commons is licensed under CC BY-SA 3.0. View a detailed description of this image.

Video 18.4.1 - California State Water Project

Video 18.4.1: "California State Water Project" by The California Department of Water Resources is in the public domain. Access a written description.

Dams: Storing Water for the Future

Dams play an essential role in California’s water management by storing water, controlling floods, generating hydroelectric power, and offering recreation. Major structures such as Oroville Dam on the Feather River, Shasta Dam on the Sacramento River, and Folsom Dam on the American River (Figure 18.4.2) are vital for supporting the state's agricultural, urban, and environmental needs. These structures ensure a stable water supply for millions of people, even during extended droughts, while also controlling flooding and generating renewable energy that reduces greenhouse gas emissions. However, they face significant challenges related to seismic hazards, sediment accumulation, and environmental impacts.

The construction of dams in California, particularly in a seismically active region, involves overcoming numerous geologic challenges (Figure 18.4.3). Dams must be designed to handle the potential for earthquakes, foundation instability, and long-term sediment accumulation. The potential flood risk due to dam failure is a stark reminder of the balance between water storage and safety. The case of the Auburn Dam, for example, which faced significant seismic risk concerns, highlights the difficulty of constructing dams in such geologically complex areas. Failure to address seismic concerns could result in catastrophic flooding, emphasizing the need for advanced engineering and design.

Case Study 18.4.1 - The Dam that Would Never Die

The proposed Auburn Dam, situated on the American River in California's Sierra Nevada foothills, has been a subject of controversy and debate since its inception in the mid-20th century (Figure 18.4.2). Initially conceived as a multipurpose project for flood control, water supply, and hydroelectric power generation, the dam's construction faced numerous challenges and opposition from environmental groups and local communities. Advocates argued that the dam would provide essential water storage capacity, particularly during periods of drought, while opponents raised concerns about the potential environmental impacts, including habitat destruction, sedimentation, and threats to endangered species such as the Chinook salmon. Despite decades of planning and intermittent construction efforts, the Auburn Dam project was ultimately halted in the 1980s due to safety concerns related to seismic activity and the potential for catastrophic failure in the event of an earthquake. Today, the remains of the partially constructed dam stand as a testament to the complexities of balancing water resource development with environmental conservation and public safety in California's dynamic landscape.

Figure \(\PageIndex{2}\): "A concept drawing of the Auburn Dam" by the U.S Army Corps of Engineers is in the public domain. View a detailed description of this image.

Another major issue surrounding dams is their impact on sediment transport and aquatic ecosystems. Dams trap sediment that would naturally flow downstream, leading to sediment deficits, erosion, and loss of habitat diversity in riverine environments. This has led to degraded aquatic ecosystems, especially in rivers historically important for species like salmon. The ongoing Klamath Dam removal project, the largest dam removal in U.S. history, is a significant effort to restore fish habitats by removing barriers that have altered natural flow and sediment processes. Scheduled for completion in 2024, the removal of four dams on the Klamath River aims to restore critical salmon habitats that are culturally and economically important to Indigenous peoples such as the Yurok.

In addition to environmental challenges, dams face ongoing concerns about their economic viability and social impacts. The thick sediment accumulated behind dams poses one of the greatest challenges in dam removal projects like Klamath, where the management of sediment post-removal is crucial for ecosystem restoration. Dams are also criticized for displacing communities, altering land use, and affecting cultural heritage sites. Despite these controversies, the role of dams in California’s water management is crucial for meeting the state’s current demands. Addressing these issues requires a balance between maintaining infrastructure, managing sediment, and minimizing ecological disruptions.

Case Study 18.4.2 - Hetch Hetchy Reservoir

The Hetch Hetchy Reservoir, located in Yosemite National Park, is a significant water storage facility in California, serving as a critical water source for the city of San Francisco and its surrounding areas. Constructed in the early 20th century, the reservoir inundated the once-pristine Hetch Hetchy Valley, sparking controversy and debates over the trade-offs between water supply needs and environmental conservation. Figure 18.4.3 is a view across Hetch Hetchy Valley before the dam was built.

The Hetch Hetchy Reservoir was built between 1913 and 1923 as part of the Hetch Hetchy Project, which aimed to provide a reliable water supply to San Francisco and the surrounding Bay Area. The reservoir, formed by the O'Shaughnessy Dam on the Tuolumne River, has a capacity of over 360,000 acre-feet and provides drinking water to over 2.6 million people.

The construction of the Hetch Hetchy Reservoir and the inundation of the Hetch Hetchy Valley sparked controversy and opposition from conservationists, led by John Muir and the Sierra Club. The valley, renowned for its natural beauty and ecological significance, was considered by Muir as the "second Yosemite" and was seen as a natural treasure worth preserving. Figure 18.4.4 exhibits what Hetch Hetchy looks like in the modern day.

The decision to dam the Tuolumne River and flood the Hetch Hetchy Valley raised concerns about the loss of habitat, biodiversity, and scenic beauty. Conservationists argued that the valley should be preserved in its natural state for future generations to enjoy and appreciate.

Figure \(\PageIndex{3}\): "View across Hetch Hetchy Valley", early 1900s, from the southwestern end, showing the Tuolumne River flowing through the lower portion of the valley prior to damming. By The National Park Service is in the public domain. View a detailed description of this image.

Figure \(\PageIndex{4}\): "Hetch Hetchy Panorama – Yosemite National Park" in 2019 by Vulpinus2 is licensed under CC BY-4.0 DEED. View a detailed description of this image.

Despite the controversy, the Hetch Hetchy Reservoir has provided significant benefits in terms of water supply reliability and municipal water quality for San Francisco and the Bay Area. The reservoir's stored water supports domestic, industrial, and agricultural needs, contributing to the region's economic prosperity and population growth.

In recent years, efforts have been made to balance water supply needs with environmental conservation and restoration in the Hetch Hetchy area. The San Francisco Public Utilities Commission, which manages the Hetch Hetchy Reservoir, has implemented measures to enhance habitat restoration, water quality monitoring, and public access to the surrounding lands.

The Hetch Hetchy Reservoir remains a symbol of the complex trade-offs between water supply demands and environmental conservation in California. While the reservoir provides critical water resources for urban populations, its construction and the flooding of the Hetch Hetchy Valley continue to evoke debates and discussions about the values of natural landscapes and the importance of sustainable water management practices.

Aqueducts: Moving Water Across the State

Aqueducts are the lifeblood of California’s water infrastructure, transporting water from areas of surplus, such as Northern California and the Sierra Nevada, to the water-scarce regions of the Central Valley and Southern California. These engineering marvels span hundreds of miles across diverse landscapes, including mountains, valleys, and deserts, overcoming significant geological and logistical challenges. The California Aqueduct (Figure 18.4.5), which carries water over 700 miles from the Sacramento-San Joaquin Delta to Southern California, is one of the largest water conveyance systems in the world. Without such infrastructure, much of California’s agriculture and urban water supply would be unsustainable.

Figure \(\PageIndex{5}\): "Aerial photo of the California Aqueduct at the Interstate 205 crossing", just east of Interstate 580 junction by Ikluft is licensed under CC BY-SA 3.0. View a detailed description of this image.

Aqueducts face significant geologic and engineering challenges, including seismic risks, terrain variability, and the need to cross fault zones. These challenges require robust designs to ensure stability and functionality, even in the face of California’s tectonic activity. Aqueducts like the Los Angeles Aqueduct must traverse mountain ranges and deserts, with extensive tunnels, pipelines, and pumping stations ensuring that water flows continuously despite changes in elevation and geography. For example, a single water molecule might fall as rain in the upper Trinity basin, only to be pumped through tunnels, aqueducts, and across the Central Valley before it reaches Southern California.

Maintaining aqueducts is essential for ensuring continuous water delivery. Aging infrastructure, sedimentation, and vegetation encroachment pose challenges that require ongoing maintenance efforts. Sediment accumulation in aqueducts, caused by natural processes in rivers and reservoirs, reduces water flow and requires regular dredging. Water quality is another concern, as contaminants like algae and biofouling can reduce water purity. Addressing these challenges involves collaboration between federal, state, and local agencies to ensure aqueducts remain functional and resilient in the face of changing climate conditions.

Levees: Protecting Against Flooding

Levees are critical for flood protection in California, especially in regions like the Sacramento-San Joaquin Delta and the Central Valley. These engineered barriers prevent flooding by confining river or coastal waters within designated areas, safeguarding communities, agricultural lands, and infrastructure from inundation. Levees are particularly vital in low-lying areas such as the Delta, where they protect against both riverine flooding and sea-level rise (Figure 18.4.6).

Figure \(\PageIndex{6}\): "A levee around a Sacramento suburb" by US Army Corps of Engineers is in the public domain. View a detailed description of this image.

Sacramento-San Joaquin Delta Levees

The Sacramento-San Joaquin Delta, situated in the Sacramento River Region and San Joaquin River Region, is a critical hub for water conveyance and ecosystem support in California. Levees in the Delta region form an extensive network of flood protection infrastructure, designed to safeguard agricultural lands, urban areas, and water supply facilities from inundation. These levees are located along the banks of the Sacramento River, San Joaquin River, and various sloughs and channels within the Delta.

In recent years, concerns have arisen regarding the aging infrastructure of the levee system along the Sacramento River and its surrounding areas. Many of these levees were originally constructed in the early to mid-20th century and were designed to withstand certain flood events based on historical data and engineering practices at the time. However, as time has passed, the effectiveness and reliability of these levees have come into question due to several factors.

Firstly, the aging infrastructure of the levees has raised concerns about their structural integrity and ability to withstand modern flood events, especially in the face of climate change and the potential for more frequent and severe flooding. The original design standards may no longer be sufficient to address the increased risks associated with changing hydrological conditions and rising sea levels.

Secondly, ongoing maintenance and repair efforts are required to address deterioration and erosion of levee structures over time. The Sacramento region's levees are subjected to various forms of wear and tear, including erosion from river currents, seepage, vegetation growth, and burrowing animals. Failure to adequately maintain and reinforce these levees could increase the risk of breaches and inundation during flood events, posing threats to public safety and property.

Furthermore, the aging infrastructure of the Sacramento levees highlights the need for comprehensive risk assessments, long-term planning, and investment in levee rehabilitation and modernization projects. Upgrading and retrofitting levee systems with advanced engineering techniques, materials, and technologies can improve their resilience to flooding and enhance their performance in safeguarding communities and critical infrastructure.

Addressing the concerns surrounding the age of the Sacramento levees requires proactive measures, including robust maintenance programs, infrastructure upgrades, and investments in flood risk management strategies. By prioritizing levee safety and resilience, the Sacramento region can better protect against the threat of flooding and ensure the long-term sustainability of its levee infrastructure.

Central Valley Levees

In addition to the Sacramento-San Joaquin Delta, levees are also prevalent along the rivers and waterways of the Central Valley, encompassing the Sacramento River Region, San Joaquin River Region, and Tulare Lake Region. These levees protect agricultural lands, rural communities, and critical infrastructure from flooding during periods of high water levels. Major rivers in the Central Valley, including the Sacramento River, San Joaquin River, and Kings River, are lined with levees to mitigate flood risks.

Coastal Levees

Along the California coastline, levees are constructed to protect coastal communities, infrastructure, and low-lying areas from storm surges, high tides, and coastal erosion. Coastal levees are located in various hydrologic regions, including the North Coast Region, San Francisco Bay Region, Central Coast Region, and South Coast Region. They are particularly prevalent in densely populated urban areas such as the San Francisco Bay Area, Los Angeles Basin, and San Diego metropolitan area.

Riverine Levees

Riverine levees are constructed along rivers and waterways throughout California to prevent riverine flooding and to channelize flow patterns. These levees are found in multiple hydrologic regions, including the Sacramento River Region, San Joaquin River Region, Santa Ana River Region, and Colorado River Region. They protect agricultural lands, residential areas, and critical infrastructure from inundation during periods of high water levels and heavy rainfall events.

Challenges and Maintenance

Levees are also prominent throughout the Central Valley, where they line the major rivers and provide flood protection to agricultural lands and rural communities. In coastal regions, such as the San Francisco Bay Area and the Los Angeles Basin, levees protect urban areas from storm surges and high tides. However, like their inland counterparts, these coastal levees face challenges related to aging infrastructure and the increasing threat of sea-level rise.

Despite their importance, levees require ongoing maintenance and modernization. The state is exploring alternative flood control strategies, such as wetland restoration, which could provide natural flood protection by absorbing excess water during flood events. Projects like the Napa River Flood Protection Project demonstrate the potential of using natural systems to enhance flood resilience. These efforts aim to balance human needs with ecological preservation, creating flood management solutions that are sustainable and adaptive to future climate challenges.

A Future of Collaborative Water Management

California’s water infrastructure, from dams and aqueducts to levees, is essential for managing the state’s water resources in a rapidly changing environment. As the state faces increasing droughts, floods, and population growth, maintaining and modernizing this infrastructure is more important than ever. Collaborative efforts between government agencies, water districts, and communities will be key to ensuring the long-term sustainability of California’s water systems, supporting both human needs and environmental health, all being dependent on the surrounding geology.

References

1. California Department of Water Resources. (2020). California's Groundwater (Bulletin 118). Sacramento, CA.
2. California State Water Resources Control Board, https://www.waterboards.ca.gov
3. California Regulations, 2008, www.calregs.com
4. National Park Service, Yosemite, Hetch Hetchy Reservoir, https://www.nps.gov/yose/planyourvisit/hh.htm
5. United States Geological Survey, 2008, National Handbook of Recommended Methods for Water-Data Acquisition, Chapter 11, https://pubs.usgs.gov/chapter11/