2025 Excellence in Environmental Engineering and Science® Awards Competition Winner

Grand Prize - Environmental Sustainability

Los Angeles Groundwater Replenishment Project

Entrant: Los Angeles Department of Water and Power and LA Sanitation & Environment
Engineer in Charge: Gabriel Vargas
Location: Los Angeles, California

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). LADWP is theprimary sponsor of the LA Groundwater Replenishment (LAGWR) Project.

Historically, LA’s water supply comes from several sources: local groundwater and imported water from the LosAngeles Aqueduct, State Water Project, and Colorado River Aqueduct. These supplies have been significantlyimpacted by environmental factors, climate change, and increasingly frequent droughts.

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

Reducing imported water purchases 50 percent by 2025;
Expanding local water sources to 70 percent of total supply by 2035; and
Reducing per capita water use 22.5 percent by 2025, and 25 percent by 2035.

With the primary source of local water supply being groundwater and the primary source of local groundwater being the from the San Fernando Basin (SFB), LAGWR focuses on increasing the supply of water available in the SFB. Expanding local water sources to 70% of total supply by 2035 requires major planning and investments in recycled water treatment infrastructure. The LAGWR Project represents the most significant step to date towards environmental sustainability for the largest municipal water utility in the nation.

Project Description

Originality and Innovation

Regulations for potable reuse via groundwater replenishment have existed in the state of California since 2014. Sincethen, water supplies have become increasingly strained due to aridification of the American West, necessitating a swift and innovative approach to supplement drinking water supplies for the City of Los Angeles (City). Currently, only onepermitted potable reuse groundwater augmentation project exists in California larger in scale than the Los Angeles Groundwater Replenishment (LAGWR) project. Groundwater recharge at this scale in a groundwater basin with a developing remediation program is an innovative approach to water supply security in a region where the majority of water is imported. 22,000 acre-feet per year of purified recycled water will be produced as part of the project, which isequivalent to the yearly potable demand of 250,000 residents. This volume is an immense water offset for watersheds becoming increasingly impacted by reduced environmental inflows like those supplying the California, Los Angeles, and Colorado River Aqueducts.

Utilizing full advanced recycled water treatment consisting of membrane filtration, reverse osmosis, andadvanced oxidation for groundwater replenishment is treatment beyond what is required by state regulations. This decision was made so the LAGWR project can adapt to stricter methods of potable reuse as regulations develop andoperations allow. Already, the project will be able to produce water eligible for direct injection into the aquifer as analternative to surface spreading, and the project will have the capacity for future modification to meet water qualitystandards set by direct potable reuse regulations in the state of California.

Quality

Only after years of research, pilots, and planning did the LAGWR project complete the planning phase. The project teamconsulted with distinguished consultants and academics in the field of water reuse, water treatment, and environmentalsustainability to conduct research and pilot studies for the purpose of developing a project with the greatest considerationfor public health and sustainability. Pilot studies testing the efficacy of six different treatment trains were conducted todocument adherence to recycled water regulations, removal of chemicals of emerging concern, and minimization ofimpacts to groundwater hydrogeology by the introduction of purified recycled water. All technologies planned for implementation have gone through rigorous scientific review, including by an independent advisory panel (IAP) of industry experts, and exhibit proven performance.

The IAP included leading experts on water treatment, environmental sustainability, hydrogeology, chemistry, microbiology, operations, risk assessment, regulations, and toxicology. The project regularly interfaced with state regulators and the IAP, receiving feedback on the project, and implementing recommendations made by both expertsand regulators. This resulted in a project of supreme quality that will effectively reduce dependence on imported water bolstering the long-term sustainability of the City’s water supply.

Comprehensive, Integrated Approach and Complexity of the Problem

The City depends on several imported water supplies. These supplies have been significantly impacted by climate change induced drought. Continually depending on water from the drought-stricken watersheds of the Colorado, Owens Valley, and Sacramento rivers has adverse environmental impacts on fragile ecosystems and dangerous implications for the reliability of the City’s future water supply. The LAGWRproject offers a way to mitigate the complex problem of importing water and creates a new reliable local water supply. Producing, storing, and utilizing purified recycled water for potable use will significantly support the reliability and environmental sustainability of the City’s water system, especially during dry periods when imported supplies aresignificantly depleted. Water not imported to Los Angeles can remain in its source watershed to replenish reservoirs andmaintain environmental habitat supporting the longevity of sensitive ecosystems.

The LAGWR project addresses the complex problem of expanding a local water supply by integrating with groundwater remediation projects and local conservation measures. Wellfields treating contaminated groundwater will also extract purified recycled water expanding the local water supply and improving water quality in thegroundwater basin beyond the objectives set by state regulatory agencies. Total water consumption continues totrend downward due to increased conservation allowing replenished groundwater supplies to offset a largerpercentage of water use. Creating alternative supplies of water combined with increased conservation will provide anenvironmentally sustainable solution to a complex water supply problem.

Contribution to Social, Environmental, and Economic Advancement

Creating a local water supply for one of the largest economic centers in the country has immense environmental,economic, and social benefits. Recurring periods of drought and a trend of aridification in source watershedsimpacts fragile ecosystems competing with demands for imported water. The LAGWR project creates a more sustainable water system by offsetting demand for imported water that creates hardship for native species insource watersheds.

The LAGWR project is essential to maintaining affordable water rates where roughly 50% of the population resides within an economically disadvantaged community (DAC). Rates for imported water are rising rapidly with rates expected to rise at least 17% in the next two years, well above the average yearly growth rate. Investment in expanding local water keeps rates affordable for rate payers and prevents price shocks resulting from diminished water supplies.

Research has shown that municipal construction projects provide positive impacts on DACs through increased opportunities for employment and economic mobility. Research conducted by the University of SouthernCalifornia and the Economic Roundtable found there is a high concentration of trained construction workers in DACs.The design-build contractor for the LAGWR project through a project labor agreement has committed to hire local firms to assist in both design and construction of the project. There are 185 census tracts designated as a DAC near theproject location that will financially benefit from the project.

The LAGWR project will also focus on educating the public on the water sector and potable reuse. As recycled water projects are continually proposed and implemented, they will need an interested and experiencedworkforce to implement and support them. The project’s public education effort will expose students and othermembers of the public to a growing industry for a fulfilling career.

Click images to enlarge in separate window.


Aerial View of Donald C Tillman Water Reclamation Plant (DCTWRP) The DCTWRP is in the San Fernando Valley within the City of Los Angeles. The DCTWRP has a maximum treatment capacity of 80 MGD with a daily average flow of ~30 MGD. There is an award-winning Japanese Garden on site that is supplied with tertiary recycled water produced by the plant. The proposed AWPF will be in the Southeast corner of the plant. The AWPF will be located near facilities hosting events from the 2028 Summer Olympic Game. All yellow outlined text and figures are proposed infrastructure for the LAGWR project. White text signifies existing infrastructure	Advanced Water Purification Facility (AWPF) This is a digital rendering of the new AWPF constructed at DCTWRP where up to 20 million gallons per day of purified recycled water will be produced. The AWPF will house the advanced water treatment technology. Also housed in the proposed facility will be a public education center with exhibits on Los Angeles’ water supply and potable reuse. The AWPF grounds will include water-wise and California native plantings with exhibits on water conservation.

AWPF southwest corner view The AWPF grounds will contain exhibits on the history of the Los Angeles river and water-wise plantings. Prior to visiting the educational center within the facility, visitors can experience three landscape zones with exhibits on topics like water conservation, native plantings, and habitat restoration. Treatment technology will be visible from the outside of the facility representing a theme of transparency while producing purified recycled water, which has in the past received significant public push back.	AWPF aerial view The AWPF roof will be outfitted with photovoltaic cells to offset the energy demand produced by advanced treatment technology. The San Fernando Valley, where the AWPF will be located, experiences very large electrical power demand during high heat events in the summer. The photovoltaic cells installed on the AWPF will help to reduce electrical demand all year and will be especially helpful during peak demand scenarios. The water-wise and California native plantings can be seen in the lower portion of the photo.

Membrane Filtration skids Pictured here is a digital rendering of the membrane filtration (MF) skids housed within the AWPF. These are the first of the three treatment technologies utilized to produce purified recycled water. The MF skids contain cylindrical membranes to remove suspended solids and pathogens. They can recover approximately 94% of the water treated. There will be eight MF skids in total	Reverse Osmosis treatment skids Pictured here is a digital rendering of the reverse osmosis (RO) treatment skids housed within the AWPF. These are the second of the three treatment technologies utilized to produce purified recycled water. The RO treatment skids contain three stages of treatment and can recover approximately 85% of the water treated. There are 168 membranes per RO treatment skid. There will be four RO treatment skids in total with space reserved for a fifth to increase the treatment capacity of the AWPF once additional recycled water is available for treatment.

Ultraviolet Advanced Oxidation reactors Pictured here is a digital rendering of the Ultraviolet Advanced Oxidation Process (UVAOP) reactors housed within the AWPF. These are the third of the three treatment technologies utilized to produce purified recycled water. The UVAOP reactors blast RO permeate with high intensity ultraviolet radiation and chlorine to oxidize chemicals and pathogens that may still be present in the water. There are hundreds of bulbs within each of the two reactors that produce the intensity of ultraviolet radiation necessary to produce purified recycled water.	AWPF Educational Center Visitors to the AWPF will be able to tour an educational center with custom made exhibits on LA’s water history, water purification, and water systems. There will be more than two dozen exhibits when visitors of all ages can learn about the future of LA’s water system. The exhibits can support multiple languages spoken within the local communities and by foreign visitors. The tour of the education center will culminate with exhibits along a balcony where visitors can marvel at the large scale of the water treatment technology.

LADWP Water Supply Portfolio LADWP imports ~90% of its potable water via aqueducts from far flung watersheds. These watersheds are susceptible to extreme droughts due to climate change and there have been two significant drought episodes in the past 20 years. These aqueducts also traverse active faults leaving them vulnerable to failure from extreme seismic activity. Water local to the City of Los Angeles makes up about 10% of total supply. With the implementation of the LA Groundwater Replenishment project, local supply sources will increase to 15% of total supply not accounting for other planned increases in groundwater extraction.	Enterprise Bridge over Lake Oroville during 2021 California drought Climate change has resulted in extreme droughts that create uncertainty in LADWP’s water supply portfolio. Singular dependence on drought-stricken reservoirs is not a long-term sustainable option for LADWP’s water supply portfolio. The sustainable option is to source water locally. Lake Oroville is the largest reservoir in the State Water Project system. This is one of the reservoirs that supplies LADWP with water. The reservoir experienced an extreme drought in 2021 where water levels were significantly lower than normal. The drought resulted in significant cuts in allocations to customers of the State Water Project including LADWP. Photo credit to Justin Sullivan / Getty Images