Building energy use varies widely across metropolitan Los Angeles. Building age, household income, home ownership rates, and land use are all correlated with energy consumption. High-income areas use more energy per building, while lower-income areas use more energy per square-foot. Account-level energy use data can help local governments devise conservation strategies. Energy efficiency programs need evaluated using energy consumption data. a r t i c l e i n f o b s t r a c tResidential and commercial buildings comprise approximately forty percent of total energy consumption and carbon dioxide emissions in the U.S. Yet, while California spends $1.5 billion annually on energy efficiency programs, limited research has explored how building energy consumption varies within cities, including the social and structural factors that influence electricity and natural gas use. We present results from an analysis of aggregated account-level utility billing data for energy consumption across the over two million properties in Los Angeles County. Results show that consumption in L.A. County varies widely with geography, income, building characteristics, and climate. Several higher-income areas have greater total energy use per building even in cooler climates, while many lower-income regions rank higher for energy use per square-foot. Energy consumption also correlates with building age, which varies widely throughout the region. Our results demonstrate the many complex and interrelated factors that influence urban energy use. While billing data is critical for devising energy efficiency programs that actually realize estimated savings and promote more sustainable cities, opening access to such data presents significant challenges for protecting personal privacy. The presented approach is adaptable and scalable to cities seeking to develop data-driven policies to reduce building energy use.

In response to the outbreak of the COVID-19 pandemic, many governments instituted “stay-at-home” orders to prevent the spread of the coronavirus. The resulting changes in work and life routines had the potential to substantially perturb typical patterns of urban water use. We present here an analysis of how these pandemic responses affected California’s urban water consumption. Using water demand modeling that fuses an integrated water use database, we first simulated the water use in a business-as-usual (non-pandemic) scenario for essentially all urban areas in California. We then subtracted the business-as-usual water use from the actual use to isolate the changes caused solely by the pandemic response. We found that the pandemic response decreased California’s urban water use by 7.9%, which can be largely attributed to an 11.2% decrease in the commercial, industrial, and institutional sector that more than offset a 1.4% increase in the residential sector. The influence of the stay-at-home practices on urban water use is slightly stronger than the combined influences of all non-pandemic factors. This study covers both metropolitans and suburbs; therefore, the results could also be useful for analysis of the impacts of COVID-19 on water use in other urban areas.

Urban stormwater infrastructure traditionally promoted conveyance. Cities are increasingly designing stormwater infrastructure that integrates both conveyance and infiltration in hybrid systems to achieve public health, safety, environmental, and social goals. In addition, cities face decisions about distribution of responsibilities for stormwater management and maintenance between institutions and landowners. Hybrid governance structures combine centralized and distributed management to facilitate planning, operations, funding, and maintenance. Effective governance in any management approach will require changes in the expertise of stormwater agencies. Recognizing the distinction between hybrid infrastructure and hybrid governance is important in long-term planning decisions for construction and management of stormwater systems. A framework is presented that relates the level and type of existing stormwater infrastructure with available capital, institutional development, and predominant citizen contributions. Cities with extensive existing infrastructure are increasingly integrating distributed, "green" approaches that promote infiltration, and must improve institutional expertise for governance decisions. For cities with little existing infrastructure, landowner management often dominates, especially when municipalities cannot keep pace with rapid growth. In between, rapidly industrializing cities are positioned to use growing capital resources to fund both conveyance and infiltration measures based on current design principles. For all cities, local management innovations, including decisions regarding public engagement, will be critical in shaping future urban stormwater systems.

In the Los Angeles metropolitan region, nearly 100 public and private entities are formally involved in the management and distribution of potable water-a legacy rooted in fragmented urban growth in the area and late 19th century convictions about local control of services. Yet, while policy debates focus on new forms of infrastructure, restructured pricing mechanisms, and other technical fixes, the complex institutional architecture of the present system has received little attention. In this paper, we trace the development of this system, describe its interconnections and disjunctures, and demonstrate the invisibility of water infrastructure in LA in multiple ways-through mapping, statistical analysis, and historical texts. Perverse blessings of past water abundance led to a complex, but less than resilient, system with users accustomed to cheap, easily accessible water. We describe the lack of transparency and accountability in the current system, as well as its shortcomings in building needed new infrastructure and instituting new water rate structures. Adapting to increasing water scarcity and likely droughts must include addressing the architecture of water management.

In western North America, massive infrastructure systems convey water over hundreds of miles to support cities, farms and economic growth. The systems were twentieth-century solutions to seasonal water scarcity, but today imported water supplies are strained. Cities are looking to water conservation and local sources of supply as future solutions. But integrated planning remains a challenge. Here, we assess economic implications of transitioning to local water supply reliance. We enhance an integrated model (Artes) of urban water management in Los Angeles County (LA County) with annualized costs for water supply sources (local and imported) and water conservation. We model cost-effective options for mitigating the effects of imported water cuts affecting nine million people within a hundred agencies, and denote associated policy options. The approach allows for a more holistic assessment that improves upon current studies, which typically compare nominal and annualized prices of different options. The concept of urban water supply trains, which include the multiple steps of acquiring, treating, distributing, and discharging or reusing water, is presented to understand emerging cycles of water supply. The analysis enhances current studies that often emphasize single agency perspectives, but also shows how existing assumptions and infrastructure shape what appear to be cost-effective options.Systematic studies of urban water management necessarily include many aspects of operations [1][2][3][4] . Engineered pipe and channel networks move surface water and runoff. Water supply utilities build and maintain systems to keep taps running. Complex networks of agencies oversee the acquisition, distribution and use of urban water and wastewater 5,6 . Landscapes and outdoor water use are especially important drivers of water demand in California, as half of urban water use goes to irrigation and trees [7][8][9][10] . Economics and social attitudes shape the expectations of residents and utilities for water supply. In many cities across the globe, climate change and population growth will test operating assumptions in the current systems 11 .Los Angeles County is an immense laboratory for exploring the future of urban water in seasonally dry climates (Fig. 1). The county currently receives 55-60% of its annual water supplies from imported sources, which include northern California through the Sacramento-San Joaquin Delta, the Colorado River basin, and the higher-altitude Owens Valley. The remainder comes from local sources, including groundwater pumping, recycled water (nonpotable or indirect recharge) and stormwater capture 5,12,13 . Of the water imported to southern California by the giant Metropolitan Water District of Southern California (MWD), Los Angeles County agencies receive approximately 40%. The City of Los Angeles receives additional imports from the Owens Valley. A shift to becoming primarily reliant on local sources is significant in a region famous for its efforts to import water [14][15][16] .Previously, to u...

Water management in the transboundary Rio Grande/Bravo (RGB) Basin, shared by the US and Mexico, is complicated by extreme hydrologic variability, overallocation, and international treaty obligations. Heavy regulation of the RGB has degraded binationally protected ecosystems along the Big Bend Reach of the RGB. This study addresses the need for integrated water management in Big Bend by developing an alternative reservoir operation policy to provide environmental flows while reducing water management trade‐offs. A reach‐scale water planning model was used to represent historical hydrology (1955–2009), water allocation, and reservoir operations, and key human water management objectives (water supply, flood control, and binational treaty obligations) were quantified. Spatially distributed environmental flow objectives and an alternative reservoir rule curve were developed. We simulated current and alternative water management policies and used an iterative simulation–evaluation process to evaluate alternative policies based on water system performance criteria with respect to specified objectives. A single optimal policy was identified that maximized environmental flows while maintaining specified human objectives. By changing the timing but not the volume of releases, the proposed reservoir re‐operation policy has the potential to sustain key ecological and geomorphic functions in Big Bend without significantly impacting current water management objectives. The proposed policy also improved water supply provisions, reduced average annual flood risk, and maintained historical treaty provisions. Copyright © 2014 John Wiley & Sons, Ltd.

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Los Angeles, which relies on large infrastructure systems that import water over hundreds of miles, faces a future of reduced imports. Within Los Angeles and its hundreds of water agencies, the capacity to adapt to future changes is influenced by laws, institutions, and hydrogeology. This paper presents a systems analysis of urban water management in metropolitan Los Angeles County to assess opportunities for increasing local water reliance. A network flow model was developed to investigate management tradeoffs across engineered, social, and environmental systems. With an aggressive regional demand target, increased stormwater capture (300%), and prioritized water reuse from existing facilities, imported water supplies can be cut by 30% while maintaining landscapes, economic productivity, and groundwater resources. Further reducing imports (by 40-50%) is possible through actions to promote additional reuse, recharge, conservation, and groundwater access. Reducing imported water without significant conservation results in likely groundwater overdraft. Fragmented networks of agencies in Los Angeles create an uneven landscape of vulnerability to water shortages. The paper discusses model applications, research needs, and policy implications of results for dry-climate cities.