Las Vegas Valley Water District Research Articles

Equity implications of Efficient Water Conservation Programs

Abstract Urban water management is increasingly challenged by the need to balance cost-effectiveness with equity considerations. This study presents a multi-objective approach to water conservation within the Las Vegas Valley Water District (LVVWD), analyzing a comprehensive dataset of water consumption and socioeconomic indicators across all single-family residences. We assess policy scenarios under two primary objectives: maximizing water savings to enhance economic efficiency and improving water affordability to promote equity. Our analysis reveals that while strategies focused on water savings reduce water use more efficiently, they tend to favor higher-income, predominantly white neighborhoods whereas prioritizing water affordability shifts resources towards lower-income, communities of color. The analysis of intermediate policy scenarios reveals the trade-offs and potential synergies between water savings and affordability. Our findings suggest that local water sustainability can be achieved by allocating resources to both high-demand and socioeconomically disadvantaged households. Highlighting the importance of integrating equity considerations into water management policies, this study provides insights for policymakers in crafting more inclusive and sustainable urban water management practices.

Policy Debates over the Southern Nevada Water Authority Groundwater Development Project: Beneficial Uses of Water in a Desert

Policy Debates over the Southern Nevada Water Authority Groundwater Development Project:Beneficial Uses of Water in a Desert Lisa W. Welsh (bio) and Joanna Endter-Wada (bio) Introduction The western United States continues to be the fastest-growing and fastest-urbanizing region of the country, while also being the most arid (Mackun and Wilson, 2011). As population and cities continue to grow in water-scarce environments, people are forced to confront value tradeoffs in trying to balance efficiency, equity, and effectiveness of water allocation practices (Ingram, Scaff, and Silko, 1986; National Research Council, 1992; Howe and Ingram, 2002; Ingram, Whiteley, and Perry, 2008). In the U.S. West, these water allocation challenges are made even more difficult as people try to increase the flexibility of an established water system deeply entrenched in American political and institutional history (Ingram, 1990; Wilkinson, 1992; Reisner, 1993; Ingram and Brown, 1998; Lach, Rayner, and Ingram 2005; Lach, Ingram, and Rayner, 2006). In this article, we examine the water conflict between the Las Vegas metropolitan area and rural communities in east-central Nevada (figure 1). The main source of Las Vegas's current water supply is the Colorado River, which flows south from Lake Powell at the Arizona-Utah border through the Grand Canyon and into Lake Mead. Nearly 40 million people in seven states, including major U.S. cities and agricultural systems, depend on Colorado River water. Over-allocation of the Colorado River, multiple competing needs, prolonged drought, rapid regional population [End Page 302] Click for larger view View full resolution Figure 1. Map of eastern Nevada showing the five groundwater basins (Snake Valley, Spring Valley, CaveValley, DryLake Valley, and Delamar Valley) targeted in SNWA's water right application for its proposed Groundwater Development Project. The Lincoln County, Conservation, Recreation, and Development Act (LCCRDA) establishes corridors in Lincoln County for water conveyance structures and shows the general location of the proposedgroundwaterpipeline.Credit: Adrian Welsh. [End Page 303] growth, and climate change have stressed this watershed, and current water policies may not contain the tools to equitably resolve emerging water conflicts (Adler, 2007; Hundley, 2009). Water managers have been investigating other solutions to survive in this new reality (U.S. Department of the Interior, 2012). In 1989, the Las Vegas Valley Water District, now part of the Southern Nevada Water Authority (SNWA), applied for water right permits to transport groundwater from rural east-central Nevada 300 miles south to Las Vegas and the surrounding metropolitan area via its proposed Groundwater Development Project (figure 1). The project would "likely be the largest interbasin transfer of water in U.S. history" (White Pine County et al. v. King, 2013). We use this case study to examine the water policy controversies involved in a rapidly growing desert metropolis seeking water from distant rural sources. Our analysis relies heavily on contributions from Helen Ingram's work on the importance of context, the significance of social constructions in policy design, the role of equity in water management, and the need to recognize multiple ways of knowing and valuing water. We follow her social construction and policy design framework (Schneider and Ingram, 1997) to explain how policy debates over the SNWA pipeline project have been framed. This case study focuses on foundational principles of water allocation that need to be reexamined as people attempt to better balance multiple needs in water-scarce environments. Framework for Understanding the Debates Ingram and Schneider (1990) argue that the content of policy has not received adequate attention within the policy sciences. While policy processes that lead to policy designs may be chaotic and changes in policy abrupt (Sabatier, 2007), the actual content of various policies is purposefully crafted to "serve particular values, purposes, and interests" (Schneider and Ingram, 1997, 3). Understanding the context in which policy designs emerge is also very important, because policies are created in response to particular situations (Schneider and Ingram, 1997; Honadle, 1999). Although contexts may change and evolve, policy designs generally endure, because the underlying foundations of policy designs are known for continuity, not for fundamental shifts (Pierson, 2004; Ingram and Fraser, 2006; Schlager and Blomquist, 2008). Policy designs socially construct target populations in positive and...

Real‐time modeling of water distribution systems: A case study

Water utilities worldwide face increasing challenges to preserve the hydraulic and water quality integrity of their water distribution networks. These challenges stem from burgeoning populations and migration to urban cities that continue to increase the load on aging, inefficient, and already strained infrastructures. This has created a pressing need for integrating supervisory control and acquisition systems with network simulation models for proactive management of these networks. Such an integrated platform is the basis for the real‐time smart water network decision support system (SWNDSS) described here. The proposed system has the power to transform a water utility's routine network modeling functions from planning and design to full‐spectrum engagement that drives more efficient operations—including managing water quality and energy, developing daily operating plans, addressing planned and emergency outages, and diagnosing and resolving field issues. Aspects of the SWNDSS ar described in a case study from the Las Vegas Valley Water District in Las Vegas, Nev.

Sliplining Rehabilitates Critical Water Supply Line

It's tough to imagine a more difficult job than rehabilitating a water pipeline passing 25 ft beneath an interstate highway bordered with steep embankments in a busy tourist area, but that's what the Las Vegas Valley Water District faced.

Excess air during aquifer storage and recovery in an arid basin (Las Vegas Valley, USA)

The Las Vegas Valley Water District in Nevada, USA, has operated an artificial recharge (AR) program since 1989. In summer 2001, observations of gas exsolving from tap water prompted a study that revealed total dissolved gas (TDG) pressures approaching 2 atm with a gas composition that it is predominantly air. Measurements of TDG pressure at well heads and in the distribution system indicated two potential mechanisms for elevated TDG pressures: (1) air entrainment during AR operations, and (2) temperature changes between the winter recharge season and the summer withdrawal season. Air entrainment during pumping was investigated by intentionally allowing the forebay (upstream reservoir) of a large pumping station to drawdown to the point of vortex formation. This resulted in up to a 0.7 atm increase in TDG pressure. In general, the solubility of gases in water decreases as the temperature increases. In the Las Vegas Valley, water that acquired a modest amount of dissolved gas during winter artificial recharge operations experienced an increase in dissolved gas pressure (0.04 atm/°C) as the water warmed in the subsurface. A combination of air entrainment during AR operations and its amplification by temperature increase after recharge can account for most of the observed amounts of excess gas at this site.

Tools and processes for calibrating large all-pipes models

Historically, computing power and software limitations necessitated that only the most significant features of the distribution system are represented. In recent years, advances in hardware and software technologies have provided the ability to include all the pipes in the distribution system. An all-pipes hydraulic model with 157,000 pipes was developed at the Las Vegas Valley Water District (District) utilising a one-to-one relationship between model features and GIS features. Calibration of such large models poses challenges in terms of collecting and handling large amounts of data from various sources, including SCADA, GIS and an enterprise database. This paper presents data integration, processes and tools developed at the District for calibration of a large all-pipes model.

High‐Tech Tools: Battle Aging Infrastructure

This article discusses how asset management software is helping the Las Vegas Valley Water District (LVVWD) prioritize its long‐ and short‐term infrastructure rehabilitation and replacement expenditures. For long‐term planning, the model predicts overall replacement needs by various pipe types – steel, plastic, etc. Rather than assuming all pipe will fail at a certain age, the model assumes a certain percentage of pipes will fail over time. The long‐term planning tools provide a way to optimize rehabilitation strategies based on avoided costs, projected break rates, and other factors. In the short term, the program is helping LVVWD prioritize which pipe sections require attention based on risk ranking. Risk is ranked according to the likelihood and consequences of a specific pipe section failing. The likelihood of failure is based on statistical failure forecasting tools. The consequence of failure is determined by the relative importance each specific pipe section plays to the system network, number of customers served, damage to major streets, etc.

With today's technology, what percentage of unaccounted‐for water is OK?

This article discusses the Las Vegas Valley Water District's (LVVWD) leak technology program. LVVWD uses an underground sounding system to monitor half of its system for leaks. The article discusses how the system works and how LVVWD determined the savings it has benefitted from since switching to this system.

Solving the Mystery of Green Sand and Water

This article discusses a case study where the Las Vegas Valley Water District (LVVWD) received a customer complaint about green tap water from a resident of a new high‐rise apartment complex. The first priorities of LVVWD's investigation were to address the customers' concerns and educate them about the problem. The study consisted of water quality analysis and particlate analysis within the high‐rise water circulation system and onsite treatment system. The two goals of the study were to ensure that the high‐rise was receiving at the meter potable drinking water that met all federal drinking water regulations, and to determine if the water quality issues were the result of LVVWD water quality or the result of water chemistry changes within the high‐rise. Particulate elemental analysis and digital photomicrography analysis are discussed.

Utility Strives to Stay Competitive, Remain Public

This article discusses the experience that the Las Vegas Valley Water District Operations and Maintenance Department had with identifying tasks that could be done by outside contractors, and enlisting employees in efficiency moves to keep itself competitive, increase customer satisfaction, and avoid a private company takeover of management and core operations.

GA Technology Analyzes Distribution System Problems

This article discusses how a number of water utilities in the United States and Australia have utilized a new optimization analysis technique to help them identify low‐cost system expansion and operating alternatives. The new technique, called genetic algorithm (GA) pipe network optimization, is summarized through the experiences of the Las Vegas Valley Water District, the Fort Collins‐Loveland Water District (Colorado), Sierra Pacific Power Co. (Nevada), and SA Water (South Australia). This article also provides advice to other water utilities interested in optimizing their distribution systems.

Fate of Organochlorine Compounds During Aquifer Storage and Recovery: The Las Vegas Experience

AbstractTwo water quality concerns with aquifer storage and recovery (ASR) operations are (1) the fate of organochlorine compounds, such as trihalomethanes (THMs), in the treated recharge source, and (2) the formation of organochlorine compounds from precursor materials following the chlorination of recovered water. The fate of chloroorganic compounds in chlorinated Colorado River water was studied during a 1989 recharge/recovery operation conducted by the Las Vegas Valley Water District (LVVWD). Water samples were obtained from two dual‐purpose wells during the pumping cycle for THMs and other indicators of organochlorine precursors. The percentage recovery of THMs was approximately the same as the percentage recovery of Colorado River water. This suggests that the removal of organochlorine compounds (e.g., by sorption) did not appreciably occur in the aquifer materials at the two well sites. Recovery of source water was incomplete. Accordingly, dissolved organic carbon (DOC), representing precursor material, remained in the aquifer at the end of the pumping cycle. The Las Vegas experience suggests that prolonged recharge and storage of Colorado River water in similar hydrogeologic basins (e.g., the Tucson basin) could result in problems with THM compliance at the well head. This will be a problem if THM standards are reduced during the interval that water is stored.

Water banking through artificial recharge, Las Vegas Valley, Clark County, Nevada

Artificially recharging the Las Vegas Valley groundwater system is one water resource management option available to the Las Vegas Valley Water District (District) to help meet increasing summer peak water demands. In a few years the existing water transmission system from Lake Mead will be unable to meet the short-term summer peak demands, and artificial recharge can be used to alleviate this constraint. In addition to meeting peak demands, artificial recharge can be used to bank the remaining portion of Nevada's unused allocation from the Colorado River for future use. At the present time (1988) the water supply for Las Vegas Valley is made up of ≈ 75% Colorado River water (about one-third of Nevada's 300 000 acre-feet consumptive use Colorado River allocation) and ≈ 25% groundwater, which is used primarily in the summer to meet peak demands. The District is investigating the feasibility of increasing the importation of treated Colorado River water into the valley during winter months, banking the water by artificially recharging the groundwater system, and subsequently withdrawing this water to meet summer peak demands and future needs. There were two major concerns regarding the feasibility of artificially recharging treated Colorado River water by deep aquifer injection. The first was the potential for calcite precipitation resulting from native groundwater and aquifer sediments mixing with treated Colorado River water which could reduce the aquifer permeability. The second was the long-term effects on well performance and production longevity by injecting through production wells. Although previous laboratory studies predicted that calcite precipitation would occur, a small-scale artificial recharge pilot study, conducted by the District in 1987, showed insignificant calcite precipitation. A larger scale demonstration project, initiated in February 1988, injected a total of 1153 acre-feet of treated Colorado River water into the principal groundwater system through two existing production wells. Injection was completed in late April and recovery of the native groundwater and Colorado River water mixture continued throughout the summer and fall. Recharge was accomplished by injection through the existing pump columns with minimal retrofitting of the existing wells and no detrimental effects to the pumps or well production rates have been determined. Water quality analyses and geochemical modeling indicate very little, if any, calcite precipitated during recharge and recovery.

Artificial Recharge in Las Vegas Valley, Clark County, Nevada

ABSTRACTArtificially recharging the ground‐water system is one water resource option available to the Las Vegas Valley Water District in response to increasing water demand during summer peak periods. The existing water‐supply system for Las Vegas Valley is limited since peak water‐use demand periods in 10 to 20 years or less will require the construction of additional facilities. To prepare for these short‐term (and longer) demands, the Las Vegas Valley Water District, in cooperation with the U.S. Bureau of Reclamation, conducted a limited ground‐water recharge demonstration project using treated Colorado River water.A major concern of water managers regarding artificial recharge is the resulting water chemistry when treated (potable) Colorado River water is injected into the ground‐ water system. Both waters are high in calcium creating a potential for calcite precipitation which, in addition to clogging the perforations in the water well casing, could potentially reduce aquifer permeabilities by clogging the pore space of the flow media.Approximately 525,000 gallons of potable water were injected into a semiconfined ground‐water aquifer over a three‐day period interspersed with two pumping periods. Water chemistry samples taken throughout the injection project showed no imbalance with regard to calcium or any other chemical constituent. Therefore, artificial recharge is feasible and is one water resource technique available to meet an increasing water demand based on the existing water quality of the Colorado River and the quality of the ground water in the area of injection.

DYNAMIC PROGRAMMING FOR OPTIMUM CONJUNCTIVE USE1

ABSTRACTThe Las Vegas, Nevada area like most semi‐arid basins, was developed through exploitation of available ground‐water resources. Area growth in this large valley has occurred in a scattered and sporadic manner with development both in incorporated areas and within the County. As a result, today there exist five major water suppliers which are: a water district, three municipalities, and a large corporation, in addition to numerous small water companies and thousands of domestic wells. In the past 20 years the area has grown from a population of less than 50,000 to over 300,000 today. The bulk of the water demand for this growth has been met from the ground‐water resource and as a result the basin is being severely mined. Current extractions are over three times the estimated annual replenishment. Rapidly declining water levels are increasing the costs of water and are creating water shortages during periods of peak demand. To meet both the current and anticipated water demands, the Southern Nevada Water Supply Project is being constructed to import additional water from nearby Lake Mead.Agriculture in the area is very limited, and primarily uses reclaimed waste water for irrigation. The chief water demands in the area are thus municipal and industrial, with the former predominating.This study was designed to determine how best the Las Vegas Valley Water District, supplier of 80 percent of the domestic water, might integrate the use of the existing ground water and anticipated imported surface water. Additionally the consequences of application of certain provisions in the Nevada Water Law were examined to determine their effects on the ground‐water system and costs of water.To achieve these objectives, a dynamic programming technique was utilized. The problem as formulated consists of a single decision variable, single state variable dynamic programming algorithm evaluated over a fifty‐year planning horizon at monthly intervals. Three alternative solutions, with different ground‐water law constraints are evaluated.In all solutions certain basic operating rules regarding ground‐water pumping distribution and use of surface‐water systems are kept constant.The problem is considered as deterministic in all respects. Recharge to ground water is assumed to equal the estimated average annual replenishment evenly distributed over the year and additionally is not considered to be a function of average basin ground water potential. The only surface supply, Lake Mead, is considered to operate at near constant elevation and not be subject to shortage conditions. In light of the size of Lake Mead, the Colorado River flow and the size of Nevada's allotment, 300,000 ac ft, the latter assumption is reasonable. Demand for water is considered as a known function of time.Optimization of conjunctive use for the Water District is based on the objective function of minimizing water production costs. Costs of distributing water are considered to be constant regardless of source, and so are not included. Also, fixed costs of amortizing the pipeline project and well fields are not considered.Results of the study are presented as a series of policy traces under each of the three alternatives considered. These traces describe the ground‐water basin response under optimal operating conditions, given an estimate as to the present worth of ground‐water pumping rights, and prescribe monthly water‐procurement schedules for the operation of the Water District.