WaterWired

AWWA Letter to EPA: 'Increasing Consistency and Transparency in Considering Benefits and Costs in the Safe Drinking Water Rulemaking'

Thanks again to G. Tracy Mehan III, executive director for government affairs at the  American Water Works Association, who sent me his 8-page letter to the EPA Office of Water about the SDWA. A while back he sent me a copy of AWWA's letter to President-Elect Joe Biden.

Download 2020 11 24 AWWA Letter on Benefit Cost Analysis for SDWA

Here goes...

November 24, 2020

Mr. Joel Corona and Mr. Michael Trombley
Office of Water
Environmental Protection Agency
Mail Code: 4101M
1200 Pennsylvania Avenue, NW
Washington, DC 20460

SENT VIA ELECTRONIC MAIL

RE: Increasing Consistency and Transparency in Considering Benefits and Costs in the Safe Drinking Water Rulemaking (RIN: 2040-AF99)

Dear Mr. Corona and Mr. Trombley,

The Spring 2020 Unified Agenda of Regulatory and Deregulatory Actions indicates the U.S. Environmental Protection Agency (EPA) will draft a regulation to increase consistency and transparency in considering benefits and costs under the Safe Drinking Water Act (SDWA). The American Water Works Association (AWWA) has a continuing interest in EPA’s drinking water program and over the past twenty-four years has supported technical dialogues, submitted data, and prepared comments to inform EPA’s SDWA benefit-cost analysis (BCA) policy and execution.

AWWA supports the use of BCAs as a useful and intelligible way to evaluate EPA regulatory alternatives while recognizing inherent limitations in such national analyses. These comments are offered in the spirit of continuous improvement to further refine current practices for the betterment of public health and affordable delivery of an essential service—drinking water.

AWWA is very interested in this new rule. Building on our history of being regularly engaged on the implementation of SDWA authorities, AWWA has prepared this letter. The following provides a brief summary of existing statutory requirements for use of BCA under SDWA in developing drinking water standards, as well as a review of common elements from AWWA comments on EPA’s previous BCAs.

Skipping 6 pages to the end...

Applying BCAs Beyond Primary Drinking Water Standards
Since the 1996 Amendments, EPA has worked diligently to conduct BCAs to support primary drinking water standards. A BCA has not always been applied to other Agency actions under SDWA. For example, the Underground Injection Control program regulation of geologic sequestration of carbon dioxide was supported by a BCA that mirrored the standard of care applied to HRRCA preparation. This is not thecase for recommendations accompanying drinking water health advisories published by the Agency.

EPA health advisories and associated recommendations can have impacts akin to primary drinking water standards and exceed thresholds set in Office of Management and Budget, as well as, Agency guidance for economically significant documents. Since AWWA’s 2015 correspondence on this issue EPA Office of Water and Office of Enforcement and Compliance Assistance have issued guidance to States and EPA Regions that encourage observed contaminant levels above health advisory concentrations to be treated as warranting immediate public notice, installation of treatment, distribution of alternative water supplies or other actions. Such health advisories consequently warrant a thorough BCA.

SDWA Processes
The SDWA regulatory process incorporates multiple steps, some of which have identifiable costs for the regulated community. It is more challenging to ascribe benefits to these interim process steps. Consequently, EPA has not been preparing a BCA in support of notices associated with the contaminant candidate list, regulatory determinations, unregulated contaminant monitoring, and six-year review SDWA provisions. Given the intermediate stage in the regulatory process each of these notices requires specific analyses to support decision-making. There is a needed emphasis on risk communication at each one of these process steps, and decision-making around the UCMR clearly includes a thorough cost analysis. It is however premature in the regulatory process to prepare a full BCA for this group of SDWA activities.

Thank you for your consideration. If you have any questions regarding this correspondence or if we can be of assistance in some other way, please contact Chris Moody (202.326.6127, cmoody@awwa.org).

Best regards,

G. Tracy Mehan, III
Executive Director – Government Affairs
American Water Works Association

cc: Jennifer McLain, EPA/OW/OGWDW
Al McGartland, EPA/OP/NCEE
Eric Burneson, EPA/OW/OGWDW

 

Enjoy!

"Every great cause begins as a movement, becomes a business, and eventually degenerates into a racket." – Eric Hoffer

Paper: 'Diverse Paradigms of Residential Development Inform Water Use and Drought-related Conservation Behavior'

I just caught this recent (18 November 2020) open-access paper by Kimberly J. Quesnel, Saahil Agrawal and Newsha K Ajami: 'Diverse paradigms of residential development inform water use and drought-related conservation behavior', Environmental Research Letters 15(12) (2020) 124009.

Read the article online by clicking here. The links below may not take you to the reference but to the original Quesnel et al. paper.

Download Quesnel_2020_Environ._Res._Lett._15_124009

Download ERL_15_12_124009_suppdata

Abstract
Widespread urbanization has led to diverse patterns of residential development, which are linked to different resource consumption patterns, including water demand. Classifying neighborhoods based on urban form and sociodemographic features can provide an avenue for understanding community water use behaviors associated with housing alternatives and different residential populations. In this study, we leveraged built environment data from the online real estate aggregator Zillow to develop neighborhood typologies and community clusters via a sequence of unsupervised learning methods. Five distinct clusters, spatially segregated despite no geospatial inputs, were associated with unique single-family residential water use and conservation patterns and trends. The two highest-income clusters had divergent behavior, especially during and after a historic drought, thus unraveling conventional income–water use and income–water conservation relationships. These clustering results highlight evolving water use regimes as traditional patterns of development are replaced with compact, water-efficient urban form. Defining communities based on built environment and sociodemographic characteristics, instead of sociodemographic features alone, led to 3% to 30% improvements in cluster water use and conservation cohesion. These analyses demonstrate the importance of smart development across rapidly urbanizing areas in water-scarce regions across the globe.

Introduction
Today, 55% of the world's population lives in urban areas with the percentage expected to grow to 68% by 2050 (United Nations Department of Economic and Social Affairs Population Division 2019). As residents move away from rural areas and into cities, suburbs, and towns, many different patterns of residential development and urban form are emerging, in turn affecting urban system sustainability (Jabareen 2006, Pandit et al 2017, Pickett and Zhou 2015). Variations in population density, housing structures, and neighborhood configurations are linked to different energy use patterns, transportation behaviors, and public health outcomes (Berrigan and Troiano 2002, Ewing and Rong 2008, Güneralp et al 2017, Stokes and Seto 2019). Housing features including urban versus suburban communities (Breyer and Chang 2014), infill development (Sanchez et al 2020), changing building and landscaping codes (Brelsford and Abbott 2017, Garcia and Islam 2019), and nontraditional housing arrangements (Barnett et al 2019) can also lead to heterogeneous residential water use behavior, which has direct implications for water resources management.

Simultaneously, sociodemographic characteristics like income and education levels often explain variations in residential water use (Schleich and Hillenbrand 2009, Shandas and Parandvash 2010, House-Peters and Chang 2011, Brelsford and Abbott 2017, Quesnel and Ajami 2017, Fan et al 2017). Together, built environment and social features provide the building blocks for defining neighborhoods and communities for urban water demand assessment and planning (Jackson-Smith et al 2016, Stoker et al 2019), which in turn dictate water supply and infrastructure investment decisions at city to neighborhood scales (House-Peters and Chang 2011, Stoker and Rothfeder 2014, Gurung et al 2016). These characteristics are also critical for understanding water conservation behavior during drought (Fielding et al 2012, Polebitski and Palmer 2013, Mini et al 2015), when strategic resource management is particularly critical.

Grouping residential customers for water resources planning and management requires linking bottom–up, household-level data about the built environment with top–down Census block-group or tract scale features. Built environment and social data can also be acquired through customer surveys (Randolph and Troy 2008, Harlan et al 2009, Willis et al 2013, Hannibal et al 2018), but these can be expensive, time-intensive, and limited in scope. Some researchers have successfully accessed assessor records on homes and parcels (for example: Chang et al 2017, Brelsford and Abbott 2017), but this data is generally challenging to obtain in bulk, digitized formats and must be acquired on a city-by-city or county-by-county basis. Around the US, a few agencies have moved to publicly available digital records like New York's Primary Land Use Tax Lot Output (PLUTO) database, which can be used for building-level water demand studies (Kontokosta and Jain 2015), although these are not yet common.

New websites like Zillow, Redfin, or Trulia that aggregate and digitize records from multiple sources, including public agencies, offer the possibility to overcome this historic obstacle, but these sources have yet to be leveraged as a tool for analyzing urban water use. Together with Census information, this housing data can be used as an alternative to traditional sources to develop a holistic depiction of communities within a city, a spatial-scale which provides the granularity of within-city information while being more practical than customer-level analyses. This research aims to demonstrate the value of combining data on single-family residential housing features and urban form from Zillow with Census data to identify residential community groupings. In turn, these classifications can help water resource decision-makers better understand their customers' water use behavior, design optimal conservation policies, and plan for future resources needs and allocation.

We performed our analysis within a single utility—exploring high-resolution data within a small area to gain insights into behavior not possible at more aggregated scales while discovering information that can be applied in a broader context. Our study area, the City of Redwood City (Redwood City) is situated on the San Francisco Bay peninsula in California and represents a microcosm of diversity—in 2017, block-group level median household income within the service area ranged from less than $40 000 (including several block-groups classified as Disadvantaged Communities) to over $220 000. The San Francisco Bay Area represents a region with varied and evolving water supply and demand regimes, making it a particularly valuable place to study urban water with lessons for other growing, semi-arid and arid regions across the Western U.S. and the world (Gonzales and Ajami 2017b). In our study, we focused specifically on single-family residential water use, which accounts for 65% of California's urban water use (California Department of Water Resources 2016) and about half of Redwood City's potable use (City of Redwood City 2015). Redwood City demand is seasonal, with higher use in the summer due to landscape irrigation.

Our research takes place over a 10-year period from 2008–2017 which included two     historic droughts and an economic recession. In particular, the 2012–2016 drought was one of the most severe in California's history (U.S. Geological Survey: California Water Science Center 2018). The drought was not only exceptional hydrologically, but also in terms of state and local political actions, public awareness, and news media coverage that led to high drought saliency and has been associated with high conservation rates (Quesnel and Ajami 2017, Gonzales and Ajami 2017a, Bolorinos et al 2020). This historic drought provides an important setting for examining not only the drivers of water conservation, but also rebound once mandatory restrictions were lifted and the drought was declared over (Gonzales and Ajami 2017a, Bolorinos et al 2020). Evaluating water conservation during the 2012–2016 drought, an extreme event more likely to occur in the future, provides an opportunity to evaluate changing residential water use behavior across customers under escalating climatic and policy regimes.

Cutting to the chase...

Discussion and conclusion
This research demonstrates the coupled role of urban form and sociodemographic characteristics in water use and drought-related conservation behavior. A crucial finding of this study is the importance of the built environment when classifying urban water customers and creating residential neighborhood typologies useful for water use and conservation analyses and developing demand management strategies. Traditionally, many researchers have stratified customers by income, finding that affluence is associated with high water use, high levels of drought-related conservation, and subsequently high conservation backslide post-drought. These water use characteristics are typically linked to more wealthy customers having bigger lots and therefore using more water outdoors. However, this study proves that income does not always correlate to high water use, and that affluent residents choosing to live in dense, new developments have very different water use patterns and water use behavior.

We bypassed previous data constraints faced by researchers, utilities, municipalities and other public agencies trying to better understand how built environment factors are linked to water use by utilizing data from an online real estate aggregator. By obtaining customer-level information from the Zillow ZTRAX database, this research for the first time demonstrates the possibility for this kind of platform to serve as a new tool for incorporating housing features into water use analyses. City and county assessors are legally required to fulfill public record requests and provide data in response to inquiries, but acquiring these individual datasets for comparative regional, state, or national assessments can be prohibitive. Thus, using aggregated data generated by Zillow and similar websites can provide a gateway for widespread analyses, for example opening the door for multi-city or even multi-state studies. These new websites offer a way to access built environment data uniformly in one place instead of filing separate records request for each service area of interest. While this research presents an alternative to traditional methods for obtaining information about the built environment, water use data remains sparse and challenging to acquire (Chini and Stillwell 2016, Josset et al 2019).

As this is the first research to use Zillow in water demand research, there are a host of avenues for future research. For example, our study was set within one utility, but the potential for Zillow truly lies in its ability to cross administrative borders. For example, where cross-city and multi-city comparisons in different counties previously required obtaining data from each individual jurisdiction, Zillow or other online aggregators store this data in one central location. Having one central database also provides the benefit of data consistency.

Additionally, here we focused primarily on neighborhood clustering to inform residential water use modeling at the monthly scale, but future studies could explore how emerging databases, online platforms, and data aggregators with high spatial and/or temporal resolution can be coupled with higher temporal resolution water use data from smart meters to better understand and predict water use and conservation. These insights could then be used to develop short-term and long-term demand management strategies. Another avenue for future research would be to investigate how different emerging urban form paradigms including infill development, peri-urban, and suburban designs shift both short- and long-term water use behavior. Land managers and water managers often do not coordinate or even talk to each other (Gober et al 2013), but with these new developments and unprecedented urbanization, there is increasing pressure for integrated planning and management.

This research lays the framework for future big data-driven urban water research and provides evidence for the implications evolving urban form on water use. Our results also point out future paths of more water-efficient urban development. Cities all over the world are expanding at rapid rates, and there are many different ways for them to develop. Here, we showed that dense housing patterns and new houses, regardless of the size, can result in lower water use than traditional sprawl. However, these low water use communities also have lower conservation rates and sometimes faster post-drought water demand rebound, and actions must be taken to account for this reduced water system flexibility. City planners and water managers must work together to develop cities of the future that house an increasingly large portion of the population and meet the wide-range of sustainability-oriented goals critical to addressing 21st century urban challenges.

Good stuff!

Enjoy!

"You can't teach an old dogma new tricks." - Dorothy Parker (quoted in @TheMVTimes via @TheWeek)

Paper: 'Avereting the Global Water Crisis - Three Considerations for a New Decade of Water Governance'

My friend and colleague Ross Hamilton (we are both on the Steering Committee of the Global Water Partnership) co-wrote this excellent
paper with Cora Kammeyer and Jason Morrison) and sent me a copy: Averting the Global Water Crisis: Three Considerations for a New Decade of Water Governance, Georgetown Journal of International Affairs, Volume 21, Fall 2020, pages 105 - 113. 

Download Averting the Global Water Crisis GJIA Nov-20

Here is the first section to whet your appetite:

Water is the most essential resource on the planet. Not only do we need it for basic survival, but our economies and natural ecosystems also rely on it. Governance structures for water management in many countries are weak and fragmented; institutional and administrative rules, practices, and processes are inadequate. The resultant challenges are of a nature and scale that truly constitute a global crisis.

Today, over two billion people live in regions where water demand outstrips supply, and it is anticipated that by 2050 there will be five billion people (half the global population) living in these "water-stressed" regions. Over 80 percent of the world's wastewater is returned to rivers and oceans untreated, polluting waterways and causing damage to ecosystems and human health and livelihoods. Overextraction and pollution of water have significantly affected the environment, with over 60 percent of ecosystem services being degraded or used unsustainably. In addition to the intrinsic value of nature, this degradation represents an annual loss of USD $3–5 trillion in natural capital. Lastly, while water has been internationally recognized as a human right, 2.1 billion people still lack access to safe drinking water, and 4.5 billion lack access to adequate sanitation services like clean, functional toilets.

Examples like the water contamination crisis in Flint, Michigan; record-breaking drought in California; the "Day Zero" crisis in Cape Town, South Africa; and the water crisis in Chennai, India, demonstrate that these severe water challenges are widespread and mounting. If the current evidence of crisis is not daunting enough, these challenges are only expected to be further exacerbated by climate change and the addition of one billion people to the global population by 2030, equating to an expected 40 percent increase in water demand.

The global water crisis is mainly a crisis of governance. Poor management and allocation of water resources by governments, communities, and water users leads to negative water outcomes like depletion and pollution. Past and current approaches to water governance have created many of the challenges we face. New approaches are needed to reverse negative trends and improve the ecological sustainability, human equity, and economic efficiency of water management. In this paper we discuss the background and recent developments of global water governance and put forth three key recommendations for reform in the coming decade, including improving groundwater governance, integrating water and climate governance, and establishing the appropriate role of the private sector in water governance.

Enjoy!

“War is God’s way of teaching Americans geography.” – Ambrose Bierce

The Water Resources Council and President Trump's Water Subcabinet: Déjà Vu All Over Again?

On 13 October 2020, President Trump issued an Executive Order titled: Executive Order on Modernizing America’s Water Resource Management and Water Infrastructure. Here's the purpose:

Section 1. Purpose. Abundant, safe, and reliable supplies of water are critical to quality of life for all Americans, fueling our economy, providing food for our citizens and the world, generating energy, protecting public health, supporting rich and diverse wildlife and plant species, and affording recreational opportunities. While America is blessed with abundant natural resources, those resources must be effectively managed, and our water infrastructure must be modernized to meet the needs of current and future generations.

Executive departments and agencies (agencies) that engage in water-related matters, including water storage and supply, water quality and restoration activities, water infrastructure, transportation on our rivers and inland waterways, and water forecasting, must work together where they have joint or overlapping responsibilities. This order will ensure that agencies do that more efficiently and effectively to improve our country’s water resource management, modernize our water infrastructure, and prioritize the availability of clean, safe, and reliable water supplies.

And the EO created an Interagency Water Subcabinet:

Sec. 3. Interagency Water Subcabinet. To promote efficient and effective coordination across agencies engaged in water-related matters, and to prioritize actions to modernize and safeguard our water resources and infrastructure, an interagency Water Policy Committee (to be known as the Water Subcabinet) is hereby established. The Water Subcabinet shall be co-chaired by the Secretary of the Interior and the Administrator of the Environmental Protection Agency (Co Chairs), and shall include the Secretary of Agriculture, the Secretary of Commerce, the Secretary of Energy, the Secretary of the Army, and the heads of such other agencies as the Co-Chairs deem appropriate. The Department of the Interior or the Environmental Protection Agency (EPA) shall, to the extent permitted by law and subject to the availability of appropriations, provide administrative support as needed for the Water Subcabinet to implement this order.

I was surprised as I did not know that Mr. Trump was that taken with water. The Water Subcabinet strikes me as a good idea and might encourage collaboration among Federal departments and agencies. In fact, an organization already exists to do that: the Water Resources Council. It was created in 1965 but was totally defunded in 1983 during the Reagan years, although it still exists on paper.

The following is on page 13 of the 2009 CRS report: Thirty-Five Years of Water Policy: The 1973 National Water Commission and Present Challenges. By the way - this CRS report is EXCELLENT! I hope it gets updated one of these days.

Download CRS_Report_35_Years_Water_Policy_1973NWC_Challenges_11May2009

Brief History of the Water Resources Council

U.S. water resource agencies largely acted autonomously in proposing project plans until an interagency Water Resources Council was established in 1965 to coordinate federal water programs and policy. The Council was created by the Water Resources Planning Act of 1965 (P.L. 89-80); it challenged more established institutional decision mechanisms of both executive and legislative branches and was subsequently disbanded in 1983. The 1965 act declares that “the policy of the Congress is to encourage the conservation, development, and utilization of water and related land resources of the United States on a comprehensive and coordinated basis by the Federal Government, States, localities, and private enterprise ..." Specific duties given the Council were to:

•   conduct continuing "assessments" of water supplies;

•   coordinate basin plans with larger regional and federal programs, including making policy

  recommendations;

•   establish "principles and standards" for evaluating projects, i.e., integrating environmental and social objectives with cost-benefit analysis;

•   review and make recommendations on basin commission plans; and

  allot financial grants to states for planning assistance. Council Activities, 1968-1978

With 50 professional staff, the Council issued unprecedented and highly detailed national water assessments in 1968 and in 1975. Dozens of river basin studies and major planning studies were completed, as was issuance of new principles and standards for project evaluation.

The Council operated in an environment dominated by a few large water project construction agencies and the legislative committees of jurisdiction. Although the Council operated as a sub-Cabinet (staff-level) committee, it was nominally made up of the Secretaries of Agriculture, Army, Health, Interior, and Transportation and the (then) Federal Power Commission chairman; later the Housing Secretary and Administrator of the Environmental Protection Agency were named as associate members, while "observers" included the Office of Management and Budget, Council on Environmental Quality, Tennessee Valley Authority, and river basin commission chairpersons.

In 1978, the Carter Administration initiated an effort to reform federal water policy—initially employing a "hit list" of about 20 large water projects for which de-authorization was sought. The Council was called upon to assist in the effort, and Council staff were used to independently review the water agencies’ project justifications. Eventually, congressional funding provisions maintained many projects and prohibited the Council’s independent reviews.

Early 1980s

In early 1981, Interior Secretary James Watt, serving as Council chairman, requested reduced Council funding. The action was consistent with the Reagan Administration's outlook that states should play a more active role in water policy activities. All the organizational and staff planning functions of the Council and basin commissions were disbanded, and a revised set of "Principles and Guidelines" were issued in 1983 as one of the last formal actions of the Council. Although the Water Resources Planning Act has not been repealed and thus authorization of the Council remains statutorily, no funding for the Council has been appropriated since FY1983.

Prepared by Betsy A. Cody and H. Stephen Hughes

I have heard that the WRC has been periodically used to enhance cooperation among agencies, as has the Water Subcabinet, even though it is only three weeks old.

So why create something when you have a perfectly good mechanism to effect change? Is the President looking for something better?

Jeff Peterson, retired EPA senior policy advisor questioned Trump's motive and noted some decisions made by the Trump Administration that fly in the face of what the EO says. Really? So what you see is not what you got.

Read Peterson's piece in The Hill.

As for yours truly - I'll sit tight for a while and give Mr. Trump the benefit of the doubt.

Maybe it's time to revisit AWRA's Water Policy Dialogues from the early 2000s. Seriously.

Download Awra_policy_dialogues_1-4_summary

Enjoy!

“When a man is wrapped up in himself, he makes a pretty small package.” – John Ruskin

Paper From Water - MDPI: 'Decoupling Urban Water Use and Growth in Response to Water Scarcity'

Just received notification of this fascinating paper from MDPI's Water: 'Decoupling Urban Water Use and Growth in Response to Water Scarcity' by Brian Richter, Kendall Benoit, Jesse Dugan, Gabriella Getacho, Natalie LaRoe, Bailey Moro, Tyler Rynne, Maria Tahamtani, and Allen Townsend. Water 2020, 12(10), 2868; https://doi.org/10.3390/w12102868

Brian Richter is the former freshwater guru for The Nature Conservancy. I use his book Chasing Water in several of my classes.

Here is a PDF: Download Water-12-02868

To read the paper online, click here. For a news story of the paper click here.

I've pasted the Abstract and Introduction below.

Abstract
Many cities in the western US face difficult challenges in trying to secure water supplies for rapidly growing urban populations in the context of intensifying water scarcity. We obtained annual data from urban water utilities across the western US to document trends in their water usage and service populations. We found that many cities have been able to accommodate population increases while simultaneously reducing their volume of water use, thereby decoupling growth from water use. This outcome is largely attributable to reductions in per-capita residential use. We identify additional untapped potential that can sustain and widen this decoupling for many cities.

1. Introduction
Access to additional water supplies has been a prerequisite for population and economic growth throughout human history. When early Roman towns outgrew their local water supplies, they engineered aqueducts to bring water from distant springs. Two thousand years later, the City of Los Angeles, California, built a 674-km aqueduct from the Sierra Nevada Mountains that unleashed a ten-fold population increase in the first half of the 20th Century. Other engineering advancements throughout the past century enabled the construction of massive storage reservoirs and wells tapping groundwater hundreds of meters deep, facilitating the growth of modern mega-cities, industries, and extensive irrigated farming regions.

 

It is therefore unsurprising that many urban planners and political leaders continue to assume that growing populations and economies will require ever-more water. Abraham and others [1] found that future demand projections by the ten largest water utilities in the State of California overestimated future demands 98% of the time, with projections that proved to be 23–26% too high even when the forecast length was only five years. The authors attributed these over-projections primarily to underestimation of the rate by which cities were reducing their per-capita usage.

 

Similarly, when the US Bureau of Reclamation in 2012 projected multi-decadal future water demands from the Colorado River of the western US, it assumed that the population-following trend of increasing water use over the past 90 years would largely continue throughout the next 50 years (Figure 1) [2]. Based on a suite of planning scenarios ranging from slow (+23%) to rapid (+93%) population growth, the Bureau projected increased water demands of 27%–49% by 2060. These projected increases in demands were based almost entirely on expected increases in municipal and industrial water needs due to population growth [2].

 

Figure 1. Historical traces of available water and actual use shown here refer to the natural supply of surface water from the Colorado River and the consumptive use of that water over time. The Colorado River Basin Water Supply and Demand Study conducted by the US Bureau of Reclamation in 2012 included water demand forecasts through 2060, based upon scenarios ranging from slow to rapid population growth [2]. It is now evident that this demand forecasting did not adequately account for recent downward trends in water consumption (historical estimates of available water and total consumptive use from US Bureau of Reclamation [3]).

However, the Bureau’s projected water demands for 2015—based primarily on forecasts from each of the seven states sharing Colorado River water—proved to be ~20% too high, even though the forecast was published only three years earlier (Figure 1). Water consumption in the basin has not increased as projected, but has instead dropped by 16% from 2000−2015 (Figure 1) [3]. The Bureau’s water planners and their state-agency peers participating in the 2012 study inadequately recognized the strength of downward trends in per-capita municipal water use during recent decades. As reported later in this paper, the nine cities we surveyed that source water supplies from the Colorado River basin lowered their per-capita use by 19–48% during 2000–2015.

 

As discussed in greater detail below, we conducted a survey of water utility managers in 20 western US cities. In our discussions with water utility staff about their motivations for implementing water conservation strategies, water scarcity and the difficulty or expense of securing additional water supplies for their growing populations were universally expressed as leading motivations. As an example, Figure 1 illustrates the fact that during recent decades, consumptive water use in the Colorado River basin has exceeded total river flow in most years since the early 1990s, enabled by progressively depleting large storage reservoirs in the basin [3].

 

In recent years, various agencies have suggested that as water scarcity expands and intensifies globally, a decoupling of water use from growth will be essential in sustaining economic growth and well-being [4]. In 2016, the United Nations Environment Programme (UNEP) warned that “half the world faces severe water stress by 2030 unless water use is ‘decoupled’ from economic growth” [4]. At the global level, economic decoupling appears to be well underway, as the global economy grew at a rate five times that of global water consumption during the past century [4].

A similar trend of decoupling has been observed in the US. After reaching a zenith in 1980, total US water use had dropped by 27% by 2015, even while the country’s population grew by 42% and GDP expanded more than six-fold [5,6]. During 2000–2015, the period of focus in this paper, substantial reductions in water use were observed in each major water-use category: Irrigation (−55%), Public Water Supply (−45%), Industrial (−40%), and Thermoelectric Power (−30%).

 

However, as UNEP asserts [4], the need and potential for decoupling is most appropriately assessed at local or regional scales; such local assessment can reveal the benefit of decoupling strategies on stressed water sources. This is exemplified by research into water decoupling efforts in China. Of 31 provinces in China, over 60% displayed strong decoupling between water consumption and economic growth after 2011, the year that China began to place a deliberate urgency on environmental protection efforts [7]. The Yellow River—the country’s second largest river basin—has been identified as a water-risk hotspot by the World Resources Institute [8]. Within this basin, the Beijing–Tianjen–Heibei region exhibited strong decoupling between water consumption and economic growth from 2004–2017, which was attributed to improved water-use efficiencies and conservation awareness on an individual scale, as researchers documented a substantial decline in the annual per-capita water footprint over this period [9]. Similarly, in a comparative urban review of China’s three largest megacities for the period 2005–2015, Guangzhou was found to display the strongest decoupling between economic growth and water usage, followed by Shanghai and Beijing.

 

In this study, we sought to better understand the policy drivers and incentives that have enabled decoupling between urban growth (measured by both population size and by gross domestic product or GDP) and water demands, through an examination of recent trends in western US cities.

 

Cutting to the chase....

6. Looking Forward

Great progress has been made in reducing urban water use in recent decades. The cities surveyed in our analysis document the fact that substantial increases in service populations can be accommodated without increasing total water use. Key to this decoupling has been their ability to push down per-capita water use at a rate greater than the demands associated with adding newcomers into their service populations.

 

There appears to be much room for continued improvement within cities that have not yet attained the high levels of performance we document here, as well as within cities that are already engaged in water conservation. DeOreo and others [18] project that residential indoor use in the US will drop by another 37% in coming years due to the fact that less than half of American homes have installed highly efficient toilets or clothes washers, two of the greatest uses of water indoors. By comparison, 86% of Australian homes now have high-efficiency toilets [39]. Leak reduction has the potential to save an additional 14% of water use in homes, on average [18]. This suggests that total indoor water use in American homes could potentially drop by at least another 50% in coming years.

 

DeOreo and others [18] also suggest that outdoor water use could be further reduced by 16% by eliminating excessive watering practices. We add that capturing rainwater for use outdoors holds great promise for alleviating pressure on freshwater supplies. Cahill and Lund [39] documented that more than 40% of Australian households are using rainwater storage tanks, whereas they are used by only a tiny fraction of American homeowners and businesses.

 

We also see great potential in the use of alternative water sources—wastewater reuse, large-scale stormwater capture, desalination, and even condensate capture from heating, ventilation, and air conditioning (HVAC) systems—as an important strategy for reducing freshwater extractions in water-stressed areas [40]. One bellwether is the City of Los Angeles’ commitment to recycle 100% of its wastewater by 2035, at which time recycled water will be providing 35% of the city’s supply as compared to only 2% today [41]. Another important factor will be the increased frequency and volume of voluntary, compensated transfers of water conserved on irrigated farms to meet urban needs, a very cost-effective strategy in regions with large acreage of irrigated farms [42,43,44].

 

We note that the challenge of holding the line on total water use appears more difficult for larger cities or utilities with very high rates of population increase, simply because per-capita use must drop by a greater extent to keep total volume constant. All but one of the cities in our survey were able to attain total volume reductions during 2000–2015 (the San Antonio Water System experienced an increase of 21% in its total water use over this period). This utility experienced extreme growth (56%) in its service population during this period, which resulted from both population growth and a merger with another water provider, and it had already substantially reduced its per-capita water use prior to 2000.

 

For cities across the US, water conservation and the use of alternative water sources will both continue to offer tremendous potential for accommodating population growth without placing further pressure on stressed freshwater supplies in the coming decades [42]. More than half of all US counties were already able to do this during 2000–2015 [10]. The challenge for urban water managers will be to fully harvest the potential for water savings that can help constrain their needs within the limits of available water supplies.

Enjoy!

 

"Despotism corrupts the person who submits to it far more than the person who imposes it." - Alexis de Tocqueville, quoted in the @washingtonpost via @TheWeek