Southern California Palimpsest: A Landscape of Ecological Abundance, Cultural Complexity and Climatological Extremes
Alison B. Hirsch, PhD, FAAR, ASLA
University of Southern California, School of Architecture
Southern California is a landscape of ecological abundance, cultural complexity, and climatological extremes. Prior to Spanish arrival, what became known as the Los Angeles Basin and the broader mountains, forests, deserts, coasts, and wetlands were inhabited and stewarded by Native peoples with ancestral knowledge of the dynamic biophysical systems that make up the richness of the region. Beginning with the arrival of the Spanish, as the land and people of California were colonized, so too were its waters—resulting in a hydrological system that is now among the most highly engineered on the planet. Over the 19th and 20th centuries, increasingly complex hydraulic infrastructures—dams, aqueducts, and concrete channels—enabled rapid urban growth, often privileging profit and private enterprise over ecological health and equity. The Los Angeles Aqueduct, completed in 1913, and the Colorado River Aqueduct, completed in 1941, redefined the metropolis, severing watersheds and fueling speculative expansion while marginalizing vulnerable communities.
Parallel to this exploitation, visionaries, including Frederick Law Olmsted, Sr. and Olmsted Brothers, brought attention to natural and cultural resources that should not be lost to human development. The Olmsted-Bartholomew Plan of 1930 for Los Angeles proposed a resilient regional green infrastructure, linking hydrology, open space, and urban growth. Its shelving left the city fragmented, paved over, and hydrologically impaired.
Today, climate change exacerbates the region’s historic vulnerabilities—drought, floods, wildfire, and inequitable risk exposure—demanding integrated, multi-benefit water planning. Recent efforts, from the Klamath River dam removal in Northern California to LA County’s Measure W, signal California’s shift toward watershed-based, restorative approaches. Landscape architects, with their systems thinking and cross-scalar design expertise, are central to these transformations. This gathering of practitioners, historians, engineers, and policymakers examines inherited conditions and emerging projects, demonstrating the profession’s critical role in addressing urban water challenges and shaping equitable, climate-resilient hydrological futures.
William Deverell
Co-Director, Huntington–USC Institute on California and the West
Rivers of Memory and Fate
Southern California’s explosive growth over the last century and a half is inextricably tied to hydrology, water engineering, gigantic public works, and the ever-changing interface between aridity and metropolitan demands. Through context and history, these prelude remarks examine the ways in which greater Los Angeles hitched growth to the acquisition of water is dramatic and complex, specific to time, place, and circumstance. But these events—the building of aqueducts, dams, concrete channels, and vast delivery systems—must also be considered together in order to understand historical patterns. Understanding those patterns (of hubris interwoven with accomplishment) will help guide planners and policymakers making critical decisions about water management going forward. These scene-setting remarks will take us from the mid-19th century forward, from the banks of the tiny Los Angeles River to the headwaters of the Owens River in the Sierra Nevada and on to the Colorado River watershed. This exploration of how planners, engineers, politicians, boosters, and the public worked together and crosswise over the future of water will help ground the day’s discussions in historical perspective.
Alexander Robinson, ASLA, AAR
Associate Professor, University of Southern California School of Architecture, Landscape Architecture + Urbanism Program, Inclusive Infrastructure Design Lab
Beyond Control: Seeking Agency in Southern California’s Water Infrastructure
The defining landscapes of Los Angeles’ most iconic water infrastructure—Owens Lake and the Los Angeles River—are the products of accidents, crises, and the willfulness of water itself. Each reveal how critical infrastructure can be reordered through complex entanglements with water and landscape. Yet even when acknowledged as hybrid terrains—part landscape, part utility—they remain notoriously difficult to design as such. Their apparent affinity for landscape architecture masks a deeper reality: they function more like roads than parks, engineered to perform, constrained by regulation, and only incidentally treated as “landscape.”
Owens Lake, once eradicated by the Los Angeles Aqueduct, now thrives as an engineered dust-control system whose ecological performance dictates water allocation. It has become an advanced regulatory landscape—where environmental, aesthetic, and economic values are continually renegotiated among multiple specialties. The LA River, by contrast, has resisted transformation: a smooth, “featureless” flood-control channel that, through protest and neglect, has evolved into an accidental greenway and tentatively embraced by Angelinos. In both, moments of rupture—broken pipes, unexpected flooding, shifts in law—have revealed water’s civic and landscape power and its levers, opening space for design to influence its trajectory.
Looking ahead, the future water infrastructure lies in deepening and shifting its entanglement with the diverse forces that exerts agency over it—regulatory bodies, flood managers, engineers, ecologists, community groups, artists, and the landscape itself. The next phase of implementation must treat them as co-authors in on-going stewardship. By hybridizing engineering, landscape architecture, environmental monitoring, and civic engagement in ways that openly negotiate and connect these practices we can embraces their agency while shaping an infrastructure with a landscape that is adaptive, equitable, and inseparable from the complex systems that sustain it.