Lorcan O’Herlihy Architects [LOHA]


According to current climate change projections by the United Nations, almost half the world's population will be living in areas of high water stress by 2030. As California enters its fifth year of drought, mandatory municipal and statewide water restrictions have localized the issue to the point of further necessary action. Such measures currently lack a viable plan for sustainable urban growth in cities such as Los Angeles, reliant on imported natural resources. Meanwhile, recent speculations fail to recognize the Los Angeles River’s inherent iconic beauty and its potential as a critical ecological resource for water use and management in a densifying city.


Lorcan O’Herlihy Architects’ WATERshed examines the relationship between urbanization and water use to develop new models of densification that recognize and tap into existing ecological and infrastructural patterns.


By opportunistically occupying public and private land remnants and capitalizing on the redundancies created by an outdated land use and infrastructural network, an entirely new model for urban regeneration can emerge. In these traditionally overlooked residual spaces, Lorcan O’Herlihy Architects [LOHA] designed a system of interventions at multiple scales, combining living, public space and water-based infrastructure into a new hybrid patchwork that will capture, recycle, purify, loop, and reconnect ground and stormwater back to the water table and the Los Angeles River.


This speculative vision embraces the Los Angeles River as it currently exists and offers a key strategy for working within the urban fabric to add moments of amplified activity. The interventions establish a web of relations and dependencies to make the best use of limited space and finite ecological resources, developing an urban culture in microcosm that sets in motion critical regional transformations.


Challenges + Opportunities


It is impossible to analyze Los Angeles as a set of isolated systems; the city emerges from the often accidental overlap of multiple varying forces, which shape moments of augmented intensity across a continuum of experiences. As the next iteration of the city is defined, we must understand how it is informed by this set of existing and new realities – decreasing buildable land, increasing density, economics, resources, and aging infrastructural systems and zoning policy – that shape modes of urban occupation and social exchange.


We are at a critical point in the history of urbanization.


The current reevaluation of urban systems in Los Angeles must also take into account the city’s inefficient use of its finite water resources. Notwithstanding exponentially rising water costs, Los Angeles still imports 88% of its water, but has the capacity to meet 82% of its water needs through wastewater recycling alone.


Despite its responsibility as the most significant piece of water infrastructure in the city, the L.A. River’s inert design is not currently equipped for the necessary multimodal approaches to water harvesting. As it stands, the channelized river is engineered to move rainwater as quickly and efficiently as possible, resulting in the loss of 88% of rainwater directly into the Port of Long Beach, reflecting an antiquated attitude towards ecological conservation and the city’s critical resources.


Los Angeles's aging infrastructure is at a breaking point after years of postponed critical maintenance. Now that maintenance is no longer viable, it is time to propose a completely new approach that prepares for the future, rather than trying to drag along an outdated and irrelevant system. The way we live has changed, the way space is perceived and used has changed, and it is time that the city's infrastructural systems evolve with new localized and nuanced patterns of occupation.


Objectives and Strategies


WATERshed reframes housing as an adaptable, localized response to the complex systems affecting urban dwellings, including the need for more effective water management strategies, new models of shared performative spaces, and improved public access policies.


LOHA’s proposed speculations along the L.A. River represent a means for working within the Elysian Valley’s existing context to plug in moments of intense, hybridized activity.


These new forms of speculation will hack into current urban and infrastructural systems along the Los Angeles River and establish a protocol for unlocking the potential of these sites, creating density through diversity, and replacing the infrastructural and temporal models of the past with a set of agile applications that adapt to a rapidly changing landscape.


Shared, Hybridized Land Use


Sited in traditionally underutilized urban spaces, these interventions couple housing with more public functions, such as parks, recreation areas, commercial uses, and transportation. These hybridized spaces create zones for constant and intense social, cultural, and economic exchange, more reflective of existing occupation patterns and desired future connections.


By integrating localized private and common space, WATERshed enables the creation of communities of people who choose to live together on the basis of shared facilities. Considering this flexible notion of land proprietorship, it is also possible to develop modes of community-based living outside the normative standards of single and multi-family housing, as suggested by the specific form, context, and scale of the various interventions. These shared spaces will help resolve the issue of affordability by distributing the financial burden over groups and communities.


As the city densifies and housing costs rise, these shared, hybridized spaces promote vested unity, using land in more efficient ways, and empowering groups and neighborhoods to alter their built environment as they see fit to accommodate their needs. The various land use typologies created by LOHA give form to the numerous power dynamics at play in urban properties and articulate the complex and intertwined ways we occupy space in the city, blurring the distinction between the private and public realm. 


Water Management


Intensified by the volatility of new weather patterns, seasonal oscillation between abundant water for condensed periods and extremely limited water for extended durations has become the new norm.


WATERshed will slow down and smooth the peak impacts of this cycle with wider distribution to existing infrastructure and by implementing new and diverse context/situation-specific strategies. The strategies will combine infiltration, capture, purification, recycling, storage, and distribution with occupiable architectural space.


By enabling a greater magnitude of collection during high-concentration water events and creating comprehensive retention and storage strategies, the interventions will facilitate the replenishment of new localized groundwater storage mechanisms, existing underground aquifers, and infrastructural water networks, including the L.A. River, amid times of drought.


This speculation by LOHA galvanizes the L.A. River’s capacity to accommodate new useful applications. The river will play a critical role, orchestrating a larger water network, consolidating various water conservation tools with an adaptability towards future ecological conditions and increased demands.


Access and Connections


Currently in the Elysian Valley and other river-adjacent neighborhoods, a hard edge of industrial and private buildings restricts river access to a few points, leading to a narrow strip of legal public space, which discourages active use. In addition, the lack of bridges across the river and generally inefficient circulation patterns isolate these communities and create problems for future growth.


WATERshed opens and occupies the hard edge to soften the boundary between the neighborhood and the river. It limits large-scale private development that blocks views and access to the river. To improve the dead-end alleys common in the neighborhood, LOHA activates these spaces through new connections, river access, and a preserved public right of way to prevent privatized ill-use.




These models represent a portion of the L.A. River watershed located in Elysian Valley and one of L.A.’s underlying aquifers. In order to implement changes in response to the drought, it is important to recognize water as the vital conduit between these large geographic forces. By studying the elements impacting the existing watershed, such as topography, distribution patterns, storage capacity, surface and groundwater contaminants, pollutants, and aquifer access, we can determine which remediation strategies will be most appropriate. After a careful consideration of the most ideal and efficient locations, the blue pins represent the WATERshed’s various interventions that collect, treat, store, and link the water above as it travels to the water below.




Sponge House


Located in yards and other underutilized remnants of an outdated zoning code, the Sponge House is composed of a sponge filtration system embedded in the house’s envelope. It intervenes in the connection between existing housing and the city’s stormwater system to collect, purify and distribute recycled water back to the neighborhood, in essence hacking an antiquated infrastructural system to enable a more localized and efficient treatment of limited water resources. The Sponge House connects to existing housing greywater (showers, sinks, irrigation, roof runoff, etc.) to treat and reuse recyclable water typically discarded directly into sewage or stormwater systems.


By short-circuiting existing runoff and drain systems, the Sponge House slows L.A.’s hydrology by acting as a conduit for stormwater on its way to the L.A. River, allowing for a longer retention, storage, and use period that captures and cleans water efficiently and appropriately.


In addition, the mass and fluctuating saturation of the sponge provides passive cooling to the internal spaces. Compared to typical construction, the use of a single building material makes it easier to recycle or repurpose for later use.


Providing an alternative proposal for L.A.’s affordability problem, the Sponge House introduces spaces able to accommodate different types of program (markets, bodegas, restaurants, Airbnb, salons) as income-generating businesses or rentable units, reflective of the current, hybridized way land is being used in these communities.


Bladder House


Utilizing a variable ratio of captured water and air as its primary building material, the Bladder House collects and stores water during seasonal high-volume rain events.  During the wet season, these bladders become one of the primary water storage areas for later community-wide access during periods of sustained drought.  Each house plays a part in a much larger, interconnected network of stored rain and recycled water, creating a greywater collection system for irrigation and plumbing purposes.


By externalizing and making visible our water use, the Bladder House serves to educate about pressing environmental issues in a way that makes potential solutions more a part of daily life and routine.


In addition to incorporating passive techniques for purification, including exposure to UV sunlight, the Bladder House’s combination of water and air also provides insulative qualities, acting similarly to a thermal mass. This increases interior comfort and reduces dependence on AC and other climate control measures.


Its inflatable structure responds quickly to changing programmatic needs, popping up in the interstitial, irregular-shaped space between existing structures. The flexible design creates temporary structures that can take on different uses reflective of specific needs that change over time, while allowing local proprietors to exert more control and responsibility over their land.


Inherent to its flexible nature, the Bladder House addresses the issue of affordability by providing the space for income-generating, co-op commercial and residential programs that activate underutilized land typically leftover on single-family lots.


Watertower House


The Watertower House connects to existing homes’ roof drainage systems to collect and store water. This intervention also ties into the new elevated Cross-Grain Circulation Path that uses its surface to collect and feed rainwater into community wells.


Helping to alleviate Los Angeles’s affordable housing crisis, the Watertower House can be built on existing commercial or residential structures as either standalone homes or accessory dwelling units.


Pump House


Where the utilization of gravity as a singular strategy is not an option, the various interventions that compose WATERshed are connected through a system of pressurized pipes. The Pump House feeds water through this infrastructure, connecting the interventions, wells and stormwater drainage pipes to the aquifer and the L.A. River.


Typically located around community or block wells, the Pump House provides the opportunity for context-specific public gathering nodes or additional income-generating commercial spaces. The limitless form of the design can accommodate whatever public program is desired by the community, including shade pavilions, walkways, or event spaces.


Reservoir House


Following Environmental Protection Agency regulations, many open-air reservoirs in Los Angeles are being capped or covered to prevent water-loss through evaporation and protect the water from sunlight-triggered chemical reactions, birds and wildlife, and other contaminants. As open-air reservoirs are being phased out of the drinking water supply in favor of underground reservoirs, we propose adding a housing component to these large, underutilized pieces of infrastructure.


The Reservoir Houses cap the Elysian Reservoir with a substrate buoyant enough to support housing, similar to a houseboat. The buoyant substrate conceals a series of pipes that provide water and additional systems needed for housing.


By constructing the buoyant substrate with either a sponge or bladder material, we can apply the principles of the Sponge House and Bladder House to a multi-unit configuration that treats and stores water with a similar technology. Collectively, all rainwater, water in the reservoir, and greywater, is treated, purified and recycled for use within the reservoir housing complex.


Transit Hub


Situated in the residual space left at the confluence of the Metrolink rail, Figueroa Bridge, the I-5 and 110 freeways, the Arroyo-Seco, L.A. River, and a proposed bike path extension of the L.A. River Greenway Trail, this proposal negotiates and reconciles these currently disparate elements while providing a hybridized program of multi-unit housing, public space, transportation and water infrastructure.


Translating the stormwater treatment principles traditionally applied at smaller scales to a multi-unit development, this project captures and purifies water with a gravity-fed system that provides recycled water to the residential units, public space, and ultimately, the L.A. River. Collected and recycled greywater is used to passively cool the entire facility.


River Bridge Cap


The L.A. River Bridge Cap combines housing and water filtration infrastructure, while providing a much-needed connective public space across the L.A. River. During high volume seasonal rain events, when the water level rises from 4 inches to 16 feet, the River Bridge Cap removes and collects large debris from the river so that it may be recycled and distributed for renewed use.


Powered by the energy generated during periods of intensified river flow, this proposal feeds a two-way system of underground stormwater pipes that extract water from the river during high-capacity rain events. This water is cleaned and stored in the network of interventions and community wells, and eventually the aquifer, for later use. Any excess water that remains after passing through this system and filling storage infrastructure is returned back to the river, as treated water. Located at each dead end road that terminates at the river, these two-way pumps expand the city’s capacity to respond to future short, intense, volatile rain storms.


In addition, the River Bridge Cap maintains and protects public river access from the surrounding community by activating the river as a public park space and discouraging the privatization of the river’s edge.


Watershed Typologies


LOHA proposes a series of plug-in interventions that address specific underperforming or absent functions in the water cycle. These interventions are located in residual spaces, often inappropriate for traditional development. The goal of WATERshed is not to create an autonomous replacement system, but to augment the existing water infrastructure in order to make the L.A. River a high-performance centerpiece for hydrology in the region.



The freeways occupy a significant amount of impermeable surface area throughout Los Angeles, which presents a unique opportunity for capturing runoff water during rain storms. The Camelbacks latch on to the side of the freeway to capture, store and slowly distribute rainwater for irrigation and other uses over time.


Water Capture Umbrellas

Placed at various points in the Elysian Valley, these umbrellas help capture water during seasonal rain events to feed and replenish WATERshed’s interventions.


Parking Lot House

Sited on a surface parking lot, this housing typology takes advantage of underutilized space to add density and mix residential and commercial uses, while capturing and recycling surface water from parking surfaces and big-box commercial roofs.


Pump Overlook

Located on the streets in the Elysian Valley that dead end into the L.A. River, the Pump Overlooks power the two-way pipe system between the river and the interventions while providing direct access to the river and a gathering spot from which to admire the iconic beauty of the channelized river.


Cross Grain Circulation

This elevated walkway serves as an aqueduct collecting runoff rainwater from the roofs of existing houses to replenish the community wells that supply water to the other interventions for further purification. The Cross-Grain Circulation helps stitch together these communities by providing an alternate mode of circulation.


Mountain House

Reinterpreting the classic L.A. hillside home, the Mountain House captures and redirects the runoff water from the hills surrounding the Elysian Valley and filters it through a gravity-fed system embedded in the house’s envelope.


WATERshed encompasses a combination of existing and proposed storm and wastewater management strategies, creating a connected system between the interventions, community wells, the L.A. River, and the aquifer below.

Lorcan O'Herlihy, FAIA
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