An Innovative Scheme to Confront the Trade-Off Between Water Conservation and Heat Alleviation With Environmental Justice for Urban Sustainability: The Case of Phoenix, Arizona

American Geophysical Union (AGU) | February 17th, 2023

Assessing Early Implementation of Urban Water Use Efficiency Requirements

Legislative Analyst's Office (LAO) | January 4th, 2024

Legislation approved in 2018 established a long‑term urban water use efficiency framework to “Make Conservation a California Way of Life.” This framework—which is

Legislation approved in 2018 established a long‑term urban water use efficiency framework to “Make Conservation a California Way of Life.” This framework—which is one component of the state’s overall water management strategy—creates new requirements for about 405 urban retail water suppliers that supply water to nearly 95 percent of state residents. This report responds to a requirement contained in the 2018 legislation for our office to assess implementation of the framework. (Our report is not able to address every aspect requested in the legislation due to framework implementation delays.)

Assessing the Microclimate Effects and Irrigation Water Requirements of Mesic, Oasis, and Xeric Landscapes

Hydrology (MDPI) | June 10th, 2022

Urban irrigation is an essential process in land–atmosphere interactions. It is one of the uncertain parameters of urban hydrology due to various microclimates. This s

Urban irrigation is an essential process in land–atmosphere interactions. It is one of the uncertain parameters of urban hydrology due to various microclimates. This study investigated the microclimate effects and irrigation water requirements of three landscape types in an arid region of Phoenix, AZ. The microclimate effect encompassed surface temperature, air temperature, and wind speed. The simulations of the three landscapes were conducted using ENVI-met software for the hottest day of the year (23 June 2011). The simulated model was validated using ground data. Results show that the mesic landscape induced cooling effects, both in the daytime and nighttime, by reducing surface and air temperatures. However, the mesic landscape showed highwater consumption because of a high leaf area density. The oasis landscape showed 2 degrees C more daytime cooling than the mesic landscape, but the nighttime warming (surface temperature) was comparable to the xeric landscape. The potential irrigation water requirement was 1 mm/day lower than the mesic landscape. Moreover, microclimate conditions varied spatially in each neighborhood. The xeric landscape showed lower wind speeds and air temperatures between the buildings. The wind speed variations in the three landscapes were inconclusive due to differences in building orientations and discrepancies in trees’ heights. The findings can have implications for restricting the municipal irrigation budget. In addition, they can help water managers in choosing a landscape in urban areas. Urban scientists can adapt the methodology to quantify urban ET in arid regions.

Assessment of California's Water Footprint

Pacific Institute | December 11th, 2012

The Pacific Institute has released the first comprehensive assessment of California’s water footprint, providing an important perspective on the interconnections betwee

The Pacific Institute has released the first comprehensive assessment of California’s water footprint, providing an important perspective on the interconnections between everyday activities and impacts to water resources – both at home and around the world. The new report, California’s Water Footprint, analyzes the state’s water footprint – that is the amount of water required to produce the food we eat, the clothes we wear, the beverages we drink, and the other goods on which we rely. The water footprint of the average Californian is 1,500 gallons per day, slightly less than the average American but considerably more than the average resident in other developed countries or in the rest of the world.

Bay Area Green Infrastructure Water Quality Synthesis

San Francisco Estuary Institute (SFEI) | June 1st, 2018

San Francisco Bay is impacted by the numerous urban pollutants that flow from the surrounding landscape during storm events. In San Francisco Bay, total maximum daily lo

San Francisco Bay is impacted by the numerous urban pollutants that flow from the surrounding landscape during storm events. In San Francisco Bay, total maximum daily load (TMDL) clean-up plans are in place for polychlorinated biphenyls (PCBs) and mercury (Hg) (Davis et al., 2007; Davis et al., 2012). As municipalities strive to reach regulatory targets, green infrastructure (GI) presents a promising solution for managing stormwater pollutants while achieving additional environmental and social benefits. However, remaining data gaps including the best design layout, media composition, and vegetation and submerged zone effects on performance can prevent local managers from accurately assessing water quality benefits provided by green infrastructure as well as the maintenance needs to sustain adequate performance.

Building Drought Resilience in California’s Cities and Suburbs

Public Policy Institute of California (PPIC) | June 1st, 2017

Droughts are a recurring feature of California’s climate. Major droughts provide an opportunity to review management responses and derive policy lessons that can better

Droughts are a recurring feature of California’s climate. Major droughts provide an opportunity to review management responses and derive policy lessons that can better prepare society for the next one. Here we take stock of how California’s cities and suburbs have responded to recent droughts, review the state’s evolving role in urban drought management, and recommend actions to increase urban areas’ drought resilience. California’s urban water supply system is complex and highly decentralized, with 400-plus utilities serving more than 90 percent of the state’s residents. Following the hard lessons learned from the 1976–77 and 1987–92 droughts, these utilities made substantial investments in drought resilience. This included diversifying supplies with new surface and underground storage, interconnections with neighboring suppliers, recycled wastewater, and water transfer agreements, as well as freeing up supplies by reducing indoor water use. Consequently, urban water suppliers generally believed they were prepared as the state entered a five-year drought in 2012.

California Single Family Water Use Efficiency Study

California Department of Water Resources (DWR) | April 20th, 2011

The California Single Family Home Water Use Efficiency Study includes data from many traditional sources such as billing data, survey data, weather data and aerial photo

The California Single Family Home Water Use Efficiency Study includes data from many traditional sources such as billing data, survey data, weather data and aerial photo information to analyze the water use patterns of a sample of over 700 single-family homes across ten water agencies throughout the State of California. Detailed flow trace data was obtained from portable data loggers which were attached to the water meters of each of the study homes. These flow traces provided flow readings at ten second intervals from the magnetic pickup, which generate 80-100 pulses per gallon. These highly detailed flow data make it possible to identify individual water use events and to categorize them by their end-use. The flow trace data tell not just how many gallons per day the home used, but how many gallons per day were used for individual end uses such as toilet flushing, clothes washing, dishwashers, showers, irrigation, faucets and leaks. Detailed use information can be pulled from the trace, giving for example, a count of toilet flushes and toilet flush volumes during a logging period. Researchers used flow trace data to determine levels of daily use in the homes and the efficiency of that use. Although the flow trace technique contains marginal error, such as from the mis-categorization of some events, it provides information on end uses-that is not available from any other source. This report summarizes the results of the study which began in 2005 and was completed in 2010. Water use patterns found during the 2007 logging period were analyzed to show how much potential remains for conservation savings from both indoor and outdoor efforts. 

California’s Next Million Acre-Feet: Saving Water, Energy, and Money

Pacific Institute | September 26th, 2010

A new analysis from the Pacific Institute recommends specific actions that can annually save a million acre-feet of water quickly and at a lower economic and ecological c

A new analysis from the Pacific Institute recommends specific actions that can annually save a million acre-feet of water quickly and at a lower economic and ecological cost than developing new supplies. The assessment notes that new actions are immediately needed to reduce the growing tensions over the state’s water resources and to address California’s persistent water supply challenges. This is a key time for California water: the California Water Bond has been tabled for at least two years and may be scrapped altogether. New reviews from around the state are calling for prompt efforts to use technology, economics, and institutional reform to address the state’s water crisis. All parties seem to agree that the state will need a diverse portfolio of solutions – but it makes the most sense to do the most effective things first. The Pacific Institute’s new report, California’s Next Million Acre-Feet: Saving Water, Energy, and Money, quantifies more than one million acre-feet of water that can be conserved through improved efficiency, with savings coming from the urban and industrial sectors and improvements in agriculture. “There is vast untapped potential to reduce our demand for water without affecting the services and benefits that water provides,” said Heather Cooley, co-director of the Pacific Institute’s Water Program and lead author of the report. “We identified how the next million acre-feet of water can be conserved in California, with approximately 30% of the savings from the urban sector and 70% from the agricultural sector. Both sectors have savings potential far exceeding this amount, and while we could have identified one million acre-feet of water savings annually in either sector alone, we’re showing how all sectors can benefit from these improvements.” In the urban sector, the report identifies water savings from replacing old, inefficient water-using devices with high-efficiency models in our homes and businesses, as well as replacing some lawns with low-water-use plants. In the agricultural sector, best water management practices include weather-based irrigation scheduling, regulated deficit irrigation, and switching from gravity or flood irrigation to sprinkler or drip irrigation systems. The efficiency improvements identified in California’s Next Million Acre-Feet require an upfront investment of less than $1.9 billion, costs that could be borne by a mix of state, federal, and local agencies and individuals – all at a small fraction of the cost of the proposed water bond. The cost of the conserved water is $185 per acre-foot for the agricultural sector and a net savings of $99 per acre-foot for the urban sector, over the lifetime of the efficiency improvement. Conserving water also conserves energy, saves money, and reduces the need for new water and energy projects.

Carbon Footprint Planning: Quantifying Local and State Mitigation Opportunities for 700 California Cities

Urban Planning (Cogitatio) | April 17th, 2018

Consumption-based greenhouse gas (GHG) emissions inventories have emerged to describe full life cycle contributions of households to climate change at country, st

Consumption-based greenhouse gas (GHG) emissions inventories have emerged to describe full life cycle contributions of households to climate change at country, state and increasingly city scales. Using this approach, how much carbon foot- print abatement potential is within the control of local governments, and which policies hold the most potential to reduce emissions? This study quantifies the potential of local policies and programs to meet aggressive GHG reduction targets using a consumption-based, high geospatial resolution planning model for the state of California. We find that roughly 35% of all carbon footprint abatement potential statewide is from activities at least partially within the control of local governments. The study shows large variation in the size and composition of carbon footprints and abatement opportu- nities by ∼23,000 Census block groups (i.e., neighborhood-scale within cities), 717 cities and 58 counties across the state. These data and companion online tools can help cities better understand priorities to reduce GHGs from a comprehensive, consumption-based perspective, with potential application to the full United States and internationally.

CE2 Model: Evaluating the Costs and Benefits of Urban Water Conservation and Efficiency Measures

Pacific Institute | April 26th, 2012

Over the past 25 years, water conservation and efficiency improvements have provided real water savings, allowing many agencies to maintain or reduce water use while meet

Over the past 25 years, water conservation and efficiency improvements have provided real water savings, allowing many agencies to maintain or reduce water use while meeting the needs of a growing population and economy. Recent studies indicate that despite the improvements that have already been achieved, significant water conservation potential remains. Indeed, California legislation passed in 2009 requires urban water agencies to reduce per capita water use by 20% by the year 2020. The economics of water conservation and efficiency are key issues. The Pacific Institute has developed the Cost Effectiveness of Water Conservation and Efficiency (CE2) Model to help evaluate the economic desirability of water conservation and efficiency measures and explore how costs and benefits can be shared among customers, water utilities, and other entities (system requirements: PC with Microsoft Excel and Access 2003* or later). The model helps document the costs of starting and running a conservation program and estimate the associated water, energy, and financial savings. It is sufficiently general and flexible to address variations in conservation measures regionally and according to the level of analysis because the model outputs are based on conditions defined by the user. The CE2 Model does not provide “the answer” as to whether a particular measure or suite of measures makes economic sense. Rather, it provides a set of financial metrics that can inform the decision-making process. The CE2 Model can also help water conservation practitioners share information across departments and with other water, wastewater, and energy utilities. The model quickly and easily calculates financial metrics that are meaningful and readily understood by planners and managers. It also provides a common platform through which to discuss the costs and benefits of water conservation and efficiency. This in turn allows utilities to exchange cost experiences and data and learn from one another more easily. The primary audience for the CE2 Model is water utility staff. The model is appropriate for wholesale and retail utilities of all sizes and can be used by agencies that exclusively provide water services, as well as agencies that also provide wastewater and/or energy services. Additionally, it may be of use to consultants, non-governmental organizations, and others interested in water conservation and efficiency and sustainable management of water resources.