California Invests in Recycled Water as Droughts Take a Toll
The state is already home to the largest potable water reuse programs in the world. Massive expansions worth more than $11 billion are in the works to keep supply steady in the face of worsening climate impacts.
Despite a troubling start to the 2021 fire season, Californians are more concerned about water and drought than any other environmental issue, according to a report just published by the Public Policy Institute of California. Northern California is scarcely immune to the impacts of drought, but 60 percent of the state’s population lives in Southern California, which depends on imported water for more than half of its supply.
Metropolitan Water District of Southern California (MWD), the largest wholesale water agency in the country, provides this water. Its principle supply sources are the Colorado River and the State Water Project, an engineering marvel that diverts water from Northern California’s Feather River to the Central Valley and Southern California.
The Colorado River Basin has experienced three years of exceptional drought in the past 20 years. Its largest reservoirs, Lake Mead and Lake Powell are only about one-third full.
MWD’s most recent assessment concluded that there will be enough supply to meet projected demand through 2045, even if that period includes five consecutive drought years. This is the result of more than a century of planning, investment, engineering and policy. However, it has become increasingly apparent that climate change is a wild card looming over both imported supply and the water that Southern California agencies can draw from local sources.
A variety of strategies will be needed to “climate proof” this semiarid part of the country, home to more people than almost every state in the U.S. One tool that has been employed for decades is recharging aquifers with purified wastewater, accomplished at a level not seen anywhere else in the world.
Major new projects using effluent from the sanitation departments of Los Angeles County and the city of Los Angeles will take this to new levels, with the potential to improve supply certainty for both Southern California and neighboring states.
Into the 21st Century
The Orange County Water District (OCWD) has played a major part in making the case for potable water reuse in Southern California, including a pivotal role in overcoming public perceptions about its safety. The OCWD does not provide water directly to users, but manages a groundwater basin that supplies water to the nation’s sixth-most-populous county.
At present, the Groundwater Replenishment System (GWRS) is the largest in the world, purifying wastewater for indirect potable use. Since 2015, the GWRS has sent 100 million gallons of purified water to four groundwater recharge basins each day. This water exceeds drinking water standards, but the 19 retail water agencies that pump water from the basin also treat it before it goes into their drinking water delivery systems.
The OCWD currently provides 77 percent of the potable water supply for more than 2.5 million people, says Mike Markus, general manager for OCWD. “We've leaned very heavily on the development of recycled water to provide water supply reliability,” he says. “We only receive about 13 inches of rainfall per year – we cannot rely on Mother Nature.”
The district's recycling efforts began with a project called Water Factory 21, which came online in 1975 to recycle treated effluent from the Orange County Sanitation District (OC San). It was the first facility in California to treat wastewater with reverse osmosis, a process in which water is forced through a semipermeable membrane to remove contaminants such as viruses, bacteria, dissolved chemicals and suspended solids.
After receiving other treatment, the water went into a series of injection wells to prevent salt water from the Pacific from coming inland and contaminating the groundwater base. The recycling effort operated for nearly three decades, producing 15 million gallons of recycled water per day.
Over time the cost of imported water rose, as did supply uncertainties. By the mid-1990s, OCWD projected that it needed 35 million gallons per day (mgd) of injection and began expansion plans, according to Markus.
The situation changed when the OC San approached it with a plan to avert the cost of building a second ocean wastewater outfall by helping to fund an expanded groundwater replenishment program. “That was the genesis of GWRS,” says Markus. “It shows that one of the keys to a successful project is having that partnership between agencies.”
Getting Ahead of Toxic Rhetoric
Beginning in the 1990s, Southern California jurisdictions encountered public and political opposition to their plans to recharge basins with purified water, setbacks that took years to overcome. OCWD reacted to the damage caused by the use of the catchy but inflammatory phrase “toilet to tap,” and took steps to get ahead of pushback from citizens.
“We hired an outreach firm before we did anything,” says Markus. “I think a lot of other projects erred because they waited until after the fact to do outreach, and by that time the damage had been done.”
Polling and focus groups provided the basis for talking points. Letters of support were gathered from the 19 retail water agencies in the county, from the CDC and from environmental groups.
Special attention was paid to the concerns of the county’s large Vietnamese and Hispanic communities, which include immigrants whose past experience with unstable water systems heightened their concerns about the safety of recycled water. A speakers bureau was created. OCWD employees who were involved in the project, including engineers such as Markus, were enlisted as speakers.
“We went out and we evangelized,” says Markus. “Over a 10-year period, we gave over 1,200 presentations, to anyone who would listen to us – chambers, rotaries, service organizations, cities and elected officials.”
Orange County’s potable reuse system treats water with microfiltration, reverse osmosis and ultraviolet light.
As result, OCWD encountered no active opposition. The Groundwater Replenishment System moved forward and was completed in 2008, raising recycling capacity to 70 mgd. By May of 2015, capacity increased to 100 mgd and is expected to reach 130 million by the first quarter of 2023, Markus says, enough to meet the needs of nearly 1 million people.
The cost of providing this water is less than the cost of purchasing imported water, says Markus, an outcome that benefits from the geology of the region. “We’re very fortunate that we have this extremely large groundwater basin that we can put this recycled water in and reuse it – a lot of other areas don’t have that.”
Despite the controversy of the '90s, potable recycling has also moved steadily forward in Los Angeles County. The latest efforts could have enormous local and regional impact.
A Regional Solution
MWD hopes to reduce its dependence on water from Northern California and the Colorado River through a partnership with the Sanitation Districts of Los Angeles County (LACSD). The Regional Recycled Water Program (RRWP) will purify water from the Joint Water Pollution Control Plant (JWPCP) in Carson, Calif., the largest of the 11 wastewater treatment plants operated by LACSD.
MWD’s efforts to ensure reliability by diversifying supply began about three decades ago, including funding to help local agencies develop recycled water projects, says Deven Upadhyay, MWD's chief operating officer. The RRWP, a $3.4 billion project with a timeline of more than a decade, would be a significant expansion of this work.
The JWPCP discharges more treated wastewater into the Pacific than any other facility in the state. “By partnering with them, we're able to purify water that’s now going out to the ocean, providing much of Southern California with a new supply,” says Upadhyay. “We're referring to it as our ‘third aqueduct’ of supply.”
LACSD has been recycling wastewater since 1962, says Basil Hewitt, a senior engineer for the districts. Its Whittier Narrows Water Reclamation Plant was the first in the nation designed to recharge groundwater basins with recycled water.
“Today, we recycle anywhere from 90 to a 100 million gallons of water a day, and at least half of that goes to a spreading basin in L.A. County and percolates into our aquifer,” says Hewitt. “Nine hundred fifty sites throughout the county have been utilizing our recycled water, but with metropolitan we can do a lot more.”
The JWPCP, the largest of the district’s wastewater treatment plants, is the last to move to recycling. Because it receives wastewater from businesses and industry as well as homes, the treated water has a higher salt concentration than usual and is too salty for reuse.
The partners have been planning and developing the RRWP for a decade, says Upadhyay. In 2019, a demonstration project began operation to establish the feasibility of bringing water from the JWPCP to potable standards, producing 500,000 gallons of purified water daily.
The 2031 goal is 100 mgd and the long-range goal is 150 mgd, says Upadhyay. “That would mean that over the course of a year it's producing more than 165,000 acre feet, which in our region is enough for about half a million households for a year.”
An overview of the processes used to purify wastewater at the Regional Recycled Water Advanced Purification Center in Carson, Calif.
Initially, the water purified by the RRWP will recharge groundwater basins in Los Angeles and Orange counties. Local suppliers will be able to withdraw it for use by businesses and residents across these basins.
A bill signed in 2017 by Gov. Jerry Brown requires the State Water Resources Control Board to adopt uniform criteria for direct potable reuse of recycled water by the end of December 2023. When this occurs, it will open the door for the RRWP (and other projects in the state) to send purified water directly to surface water reservoirs.
Water agencies outside the state also have a vested interest in the success of the RRWP. The Southern Nevada Water Authority, the Central Arizona Project and the Arizona Department of Water Resources have all expressed interest in helping to fund it, says Upadhyay, in exchange for some of California’s Colorado River supplies.
Los Angeles Commits
Los Angeles Mayor Eric Garcetti’s Green New Deal, launched in 2019, included a target of recycling all the city’s wastewater for beneficial use – including, but not limited to potable use – by 2035. Achieving a 100 percent recycling rate at the Hyperion Water Reclamation Plant (HWRP), one of the largest in the world, would make a huge difference in the share of recycled water in the city’s water supply. Currently, this stands at 2 percent; 100 percent recycling at HWRP could increase this to 35 percent, according to city officials.
Hyperion 2035 is a joint effort between L.A. Sanitation and Environment (LASAN), the Los Angeles Department of Water and Power (LADWP) and the West Basin Municipal Water District. The project took its first step in July 2020, when the city broke ground for construction of a pilot facility expected to be in operation by the beginning of 2022. Testing there will guide final decisions about the technology to be used at the Hyperion reclamation plant.
“We have a long history of water recycling,” says LASAN engineer Huub Cox, who is managing its share of the Hyperion 2035 program. “Some of the technologies we will be using have already been implemented at other water reclamation plants in the city.”
Based on projections of wastewater coming to HWRP in 2035, 100 percent recycling could result in up to 217 mgd of potable water, says Cox. This is one-third of the city’s daily need.
LADWP will convey water purified at Hyperion. As part of the project, it will construct a new pipeline that can replenish the San Fernando Groundwater Basin, and this work will need to keep pace with the development of HWRP’s recycling output. When allowed by regulators, LADWP could also take water to the RRWP backbone system and the L.A. Aqueduct Filtration Plant for direct potable use.
This is a huge investment, but even with the challenges that come with executing a project on this scale, it offers this water-stressed region a path to water security with a greater degree of certainty than second-guessing weather patterns.
“For a region like Los Angeles, recycled water is a must,” says Cox. “Because of climate change, our sources of water will be less and less over time – if you have to take water from the Bay Delta or the Colorado River, who can say that we will still have that water 50 years from now?