2018 Excellence in Environmental Engineering and Science™ Awards Competition Winner

E3S Superior Achievement Award

Superior Achievement in Environmental Engineering and Science

Category Entered: Environmental Sustainability

LA's Water Conservation Potential Study Targets a Sustainable Future

Entrant: Los Angeles Department of Water and Power
Engineer in Charge: David Pettijohn, P.E., BCEE
Location: Los Angeles, California
Media Contact: Jevon Lam


Entrant Profile


The Los Angeles Department of Water and Power (LADWP), the largest municipal water and power utility in the nation, serves water and electricity to nearly 4 million residents and businesses in Los Angeles (LA). Historically, LA's water supply comes from several sources: local groundwater and imported water from the Los Angeles Aqueduct, State Water Project, and Colorado River Aqueduct. These supplies have been significantly impacted by environmental factors, climate change, and increasingly frequent droughts.

LADWP is proactively addressing these supply challenges by pursuing LA's Sustainable City pLAn goals (pLAn). LADWP is aggressively expanding water conservation, stormwater, and recycled water supplies. The development of these drought-resilient, local supplies will help achieve the pLAn's ambitious water supply goals of:

  • Reducing imported water purchases by 50 percent by 2025;
  • Expanding local sources of water to 50 percent of total supply by 2035; and,
  • Reducing per capita water use by 20 percent by 2017, 22.5 percent by 2025, and 25 percent by 2035.

Meeting the pLAn goals will require over 45 billion gallons per year in additional conservation by 2035. To achieve this extraordinary water savings, LADWP and consultant CDM Smith jointly completed a Water Conservation Potential Study. The study determined the current saturation levels and remaining conservation potentials in LA, identified additional program opportunities, and conducted economic analysis to forecast cost-effective investment levels. The study is the first of its kind in the US and is a pioneering achievement in the areas of research, planning, and environmental sustainability.

Project Description

Since 1977, the Los Angeles Department of Water and Power (LADWP) has been a national leader in advancing water conservation. To help improve water efficiency in Los Angeles (LA), LADWP's Water Conservation Program implements a wide variety of strategies that includes:

  • Residential and commercial customer rebate programs
  • Focused water conservation outreach, education, and media advertising programs
  • Progressive local water efficiency codes and active enforcement
  • Conservation-based rate structure that is fully volumetric and multi-tiered

LADWP's conservation achievements have been instrumental for LA's water reliability and helped keep LA's water demand levels flat for the last 40 years despite a population increase of over 1 million. The achievements have decreased residential water demand to 69 gallons per person per day (GPCD), which makes LA the most water efficient of all major US cities.

In recognition that saturation of water efficient fixtures is high in some customer sectors, LADWP initiated a groundbreaking effort, the Water Conservation Potential Study (WCPS), to comprehensively assess the remaining conservation potential for each sector and evaluate cost-effective future investment levels. The WCPS took $1 million and 3 years to develop, and consists of the following three main components:

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The WCPS projected 45 billion additional gallons of water per year in conservation potential (enough water to serve 420,000 LA homes) and paves the way for LADWP to meet the ambitious goals in the LA's Sustainable City pLAn goals. LADWP will be tapping into the entirety of this remaining conservation potential to reduce water use an additional 25 percent by 2035. Over the last 3 years, accomplishments that have been achieved thanks to early study findings include:

  • Expansion of LADWP's Turf Removal Program, which achieved 46 million square feet in turf removal. This equates to 92 percent of the 50 million square feet goal Governor Brown set for the entire State of California.
  • Improvements to rebate and focused outreach programs, which helped reduce residential GPCD by an additional 22 percent from already efficient baseline levels.
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Integrated Approach

To ensure representative study findings, the WCPS collaborated with a wide variety of stakeholders that included local residents, multifamily owners & property managers, industry associations, and businesses. LADWP also collaborated with other LA City Departments to gain additional stormwater capture, runoff water quality, and wildlife habitat benefits for City facility landscape retrofit projects.

Furthermore, the extraordinary conservation savings minimize LA's environmental footprint by reducing energy needs to transport, treat, distribute, and heat water. The conservation savings significantly reduces LA's reliance on imported water from Northern California and the Colorado River. This improves overall supply reliability, wildlife preservation, greenhouse gas emissions, and environmental sustainability for California.

Quality

Significant work was dedicated to collecting high quality data that is representative of LA's customer base with a high degree of statistical validity. Highlights of the robust efforts include:

  • 615 single-family phone surveys
  • 72 single-family home audits
  • 4,025 multifamily online surveys
  • 100 City facilities onsite audits
  • Extensive research with satellite imagery, GIS mapping, billing and rebate databases, literature review, and interviews with industry experts
  • Use of prior audits for all schools in the Los Angeles Unified School District
  • A robust, "living" computer forecasting model that can update with emerging technology and innovations

Survey and audit data exceeded LADWP's statistical validity target of 95 percent confidence level. In addition, LADWP dedicated the entire last year towards data quality assurance and calibration. This dedication towards quality helped proficiently answer all questions needed for long-term planning.

The WCPS has been recognized as a prime example for water suppliers to follow by industry peers that include the California Water Efficiency Partnership and the National Alliance for Water Efficiency.

Originality and Innovation

The ambitious scope makes the WCPS the first of its kind in the US. There have been other studies completed, but they typically focused on determining saturation levels of select water fixtures. This information provides a general picture of conservation opportunities, but it lacks the in-depth understanding needed for comprehensive program planning.

The WCPS takes it to the next level by conducting research and analysis necessary to successfully answer questions needed for effective long-term planning. The study's Water Conservation Model (WCM) builds comprehensive water use profiles for LA's customer sectors, analyzes cost-effectiveness of increased investment levels, and projects achievable conservation potentials to set realistic 20-year outlooks. This forecast model is what exemplifies the WCPS as an innovative, pioneering project amongst the conservation industry in California.

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Complexity

Many components required to determine citywide conservation potential are costly and/or difficult to complete. The following are the complex challenges experienced by previous industry work, which the WCPS successfully overcame:

Gathering statistically valid and representative data

  • LADWP used a variety of data collection methods that included phone surveys, online surveys, onsite audits, literature review, industry expert consultations, and billing data to determine the City's saturation levels.

Long-term conservation potential is difficult to forecast accurately

  • LADWP developed a robust computer model that answers all questions needed for long-term program planning:
    1. Analysis for each of LADWP's major customer sectors: single-family, multifamily, commercial/industrial, and City government.
    2. Annual projections of water use reductions for all major water end uses from rebate investments and State & local water efficiency codes.
    3. Economic analysis of present value benefits, internal-rate-of-returns, and benefit-cost ratios of program investments.
    4. The ability to update rebate and code parameters to incorporate future technology and standards.

Social and Economic Advancement

The extraordinary volume of conservation potential identified by the WCPS will help ensure the sustainability of LA's future water supply. The implementation of water efficiency measures will result in substantial reductions in greenhouse gas emissions and cost savings for customers in both water and energy, which increases available funding for consumer spending and business growth.

The WCPS also identified over $350 million in LADWP investment opportunities. These investments will retrofit water fixtures and landscapes and will create tremendous business and job opportunities. In addition, park and city facility improvements will yield additional recreation and educational benefits that will improve social well-being.


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