The Walnut Valley Water District in southern California uses recycled water as a way to “drought-proof” the area’s potable supply.
What’s the secret to delivering a reliable supply of recycled water in a service area that includes four independently governed municipalities and a portion of unincorporated Los Angeles County? What kind of regulations is the district subject to? What about public reaction?
“Recycled water,” says Michael Holmes, general manager at southern California’s Walnut Valley Water District, “is fundamental to our overall water resources strategy.” Located 20 miles inland from downtown Los Angeles, in a 29-square-mile area of former cattle ranches and dry land farms, the Walnut Valley Water District (WVWD) has been marketing recycled water for over two decades, encouraging its use for commercial and institutional irrigation as a way to “drought-proof” its potable water supply.
The most important factor for success, says Holmes, is a long-term organizational commitment that includes good service and developing a congenial relationship with customers. Second is maintaining an ongoing program of outreach and education to keep the community informed about opportunities for using recycled water.
Like a number of post–World War II districts formed as development began outstripping available groundwater in southern California, the WVWD is totally dependent on imported water provided by the Metropolitan Water District (MWD), the region’s mega-wholesaler. What groundwater is available in the WVWD service area comes from the shallow (100 to 140 feet) Puente Basin. Flows are not only grossly inadequate but also high in total dissolved solids (TDS).
Today the WVWD serves potable water to a population of 100,000 residents and businesses in the largely residential city of Diamond Bar (population 59,000, with almost 20% of its land used for parks and recreation), portions of the City of Industry (which provides 37% of the basic manufacturing jobs in the San Gabriel Valley), and the cities of Walnut and West Covina, plus easterly sections of unincorporated areas of Los Angeles County. To accomplish this, the district maintains 370 miles of potable distribution mains, 16 pump plants, 16 booster pump stations, 37 pressure-regulating stations, and 26 aboveground reservoirs that collectively provide a storage capacity of over 85 million gallons. The water the district imports comes treated, which means the WVWD maintains no treatment or filtration facilities. Sewage is handled by the Los Angeles County Sanitation Districts, and effluent from the districts’ Pomona Water Reclamation Plant provides the WVWD with its recycled water supply.
The WVWD provides a total of 7.5 billion gallons of potable water annually. As of 2005, service connections included 23,817 single-family residences, 997 multifamily residences, 792 commercial and institutional connections, and 150 industrial and 322 landscape irrigation connections. Single families use the lion’s share of the water, a total of 16,717 acre-feet, while multifamily residential customers account for 2,239 acre-feet; commercial and institutional customers, 2,455 acre-feet; industrial customers, 489 acre-feet; and landscape irrigation, 1,202 acre-feet.
One of the district’s first projects after it was established in 1952 was to partner with the City of Pomona and the Rowland Water District to construct a joint pipeline to transport water from two MWD treatment plants to the district’s storage reservoir. The pipeline remained the WVWD’s sole supply of potable water until 1993, when a second 5-mile-long transmission line was constructed, doubling capacity and providing a backup in case of failure in the original line. Given the growth in its service area and southern California in general, the WVWD Board of Directors had already identified the need for an alternative source of water to protect its imported supply in case of restrictions due to drought, overdraft, or other conditions. Action was taken on this commitment in 1986, when the board authorized construction of an $8.5 million recycled water system.
The initial recycled water system included just 17 miles of pipe and one 2-million-gallon storage tank plus one recycled pump station with a main capacity of 3,500 gallons a minute and a booster pump capacity of 500 gallons per minute. With this, the district originally served 21 customers and irrigated a total of 340 acres. In 1992, as development in the service area continued to boom, the WVWD added a second 2-million-gallon storage tank. The district also built what it describes as two recycled wells, one in 1989 with a pumping capacity of 330 gallons per minute and the second in 2003, which pumps 155 gallons per minute. The wells tap into irrigation runoff, which is mixed with treated effluent from the Pomona treatment plant to dilute its high TDS content. Over the past 20 years, the district has also doubled the amount of pipe in its recycled system and currently serves 227 metered connections, for a total of 600 irrigated acres.
The WVWD sells 537 million gallons of recycled water a year, and current plans call for expanding the system even further. According to Ann Heil, supervising engineer for the Los Angeles County Sanitation Districts, this makes the WVWD one of the Pomona plant’s largest customers in terms of number of users, although communities with a more expansive industrial base draw more water.
 |
Photo: Walnut Valley Water District |
| Purple trucks service the recycled water supply in Walnut Valley. |
Current recycled water customers in the WVWD’s service area include industrial complexes and commercial buildings (the City of Industry has a 12% landscape requirement for new development); homeowner associations, which use recycled water to irrigate common areas; and community parks and schools. There are no plans to supply water for such direct uses as toilet flushing or to serve residential users with recycled water, an application that, from the district’s viewpoint, doesn’t provide a satisfactory return on investment. According to Assistant General Manager and Chief Engineer Erick Hitchman, a delivery system to serve residential customers would be too expensive to construct, especially since most of it would have to be built in areas that are already developed, which would mean considerable construction challenges. More fundamentally, the district calculates it gets more potable water offset from its residential conservation programs than it would from requiring homeowners to use recycled water for irrigation.
“Commercial and institutional customers are our largest water users,” says Cregg Zimmerman, WVWD director of operations. “If you can get these types of users to utilize recycled water for irrigation, it makes a far more significant difference than adding a few single-family homes. Homeowners can do their part with water-saving devices such as low-flow toilets and employing water-conservation strategies.”
At the Los Angeles County Sanitation Districts, Water Recycling Coordinator Earl Hartling agrees with the WVWD’s marketing strategy. Over the years, the districts have settled on targeting big-ticket users. “If you use as much water on one golf course as 1,000 homes,” says Hartling, “it’s a better investment.”
In addition to the cost of constructing lines for residential uses, regulations that protect against cross connections and a host of other state-mandated requirements would make it difficult for homeowners. Like commercial customers, individual residents would be required to install backflow devices, for example, which have to be tested annually. Additionally, each property owner would be required to secure a permit at a cost of over $1,000. All properties irrigated with recycled water must also have a designated supervisor onsite—no big deal for commercial or institutional customers, who can rely on a landscape contractor, plumber, or maintenance supervisor, but which could be troublesome for homeowners.
“The issue is nonprofessionals handing the recycled water,” says Hartling. “No offsite runoff is allowed. Signs must be posted and recycled water system components properly identified. [The WVWD uses service trucks painted purple for its recycling system.] And special hookups are required to discourage any casual draw from a recycled system such as attaching a garden hose.” (All of this aside, Zimmerman reports that the WVWD’s recycled ordinance actually allows for the use of recycled water to irrigate large multi-acre residential parcels, but so far there have been no takers.)
“The one really big benefit to recycled water for large landscaped areas,” says Zimmerman, “is the relative drought-proofing of our potable supply. If there’s an allocation on imported water, customers using recycled water to irrigate parks or schoolyards wouldn’t be impacted to anywhere near the extent of someone using imported water.” At the Sanitation Districts, Hartling suggests another scenario—commercial customers who are impatient with elaborate potable conservation strategies. “If large industrial users have to spend too much effort on conserving water,” says Hartling, “they’re likely to relocate—and there goes your tax base.”
The WVWD estimates its service area is almost 90% built-out and future development will primarily be in-fill and redevelopment. “We’re currently putting in a distribution system for a 268-home subdivision,” says Hitchman, “which will probably be the service area’s last large housing development.” This means the district’s future drought-proofing plans call for attracting more commercial and institutional irrigation customers. The target is to expand from 1,600 to 2,000 acre-feet of recycled water annually to 4,500 acre-feet. According to Hitchman, if the district is able to generate 2,500 feet of recycled water system expansion and simultaneously save 1,000 acre-feet a year of potable water with conservation measures, it will be able to accommodate the service area’s projected growth without adding to its current imported potable supply.
The WVWD’s goals are in concert with those of the county Sanitation Districts, which targeted expanded sale of recycled water for irrigation and industrial use during the same two decades the WVWD has been slowly expanding its recycled water market. “Our whole system really grew up to provide recycled water,” says Heil, “and the Sanitation Districts’ goal is to maximize its use.” In 1962 the districts began building plants to produce tertiary treated effluent and discharge solids back in the sewer system to be treated at a central plant near the coast. Although recycled water use varies with precipitation, Heil estimates approximately 40% of the 145 million gallons a day of effluent the Pomona Water Reclamation Plant produces goes to direct uses such as irrigation. The rest is discharged into a tributary of the San Gabriel River for indirect (permitted) or incidental groundwater recharge.
The county’s six reclamation plants operate under individual permits from the Los Angeles Regional Water Quality Control Board, which functions as the local arm of the state’s Water Quality Control Board. The regional board issues separate permits to each plant, one each to cover discharge to receiving waters and distribution of recycled water. “As the provider of this water, we have certain obligations to make sure it’s used properly,” says Heil. “In lieu of each individual water user having its own permit, we’re the permit holder, and it’s our job to make sure users such as the Walnut Valley Water District do their job properly.” The Sanitation Districts are currently in the process of consolidating recycled water use regulations with the county Department of Public Health, and the joint regulations will be issued in conjunction with a user’s handbook. The idea is to make it easier for customers to comply and for the Sanitation Districts to enforce regulations.
Although the tertiary treated effluent produced by Los Angeles County’s plants meets strict state Title 22 requirements, making it safe for full-body contact, recycled water users must abide by state regulations designed to minimize the chance the public will ingest recycled water. Hours of irrigation in parks are limited, for example, so picnic tables that might inadvertently be sprayed can dry before normal hours of public use. These state restrictions are passed through to recycled water users by the Los Angeles County Department of Public Health as the agency charged with enforcing the Title 22 regulations. (Only Long Beach, Pasadena, and Vernon have their own health departments). The county reviews and approves customers’ plans for their recycled systems and must inspect the systems before they can be operated. According to Paul Wong, chief environmental health specialist for the Department of Public Health, the department also checks for violations of other county codes such as plumbing and public health and safety.
California law makes it a crime to use potable water for non-potable uses, which means that individual water districts can require commercial and institutional users to use recycled water for irrigation when it’s available. “If we bring a recycled main down a street, we put a meter in up the property line and inform customers along that main they are required to hook up,” says Zimmerman. “We work with them to design the system and to secure permitting. We review all their plans. The county health department issues a permit, and we issue an annual permit as well. This is another regulation passed through from the Sanitation Districts. Other requirements include users to notify us if they have any onsite breaks. If it’s larger than a specified size, we have to notify the Sanitation Districts. If there’s a pipeline failure in which more than 50,000 gallons of water are discharged, we also have to notify the districts.”
According to WVWD Director of Administrative Services Sandra Olson, communities in the service area have generally accepted recycled water for irrigation, although some individual users have raised issues. Fast food restaurants, for example, have expressed concern about the public’s perception of using recycled water in their outside play areas. To resolve this, the district reinforces hours of irrigation so the systems aren’t running when kids are around. “Sometimes developers complain about having to put in dual systems,” says Zimmerman, “and sometimes customers complain about the cost of installing two meters. In these cases, we remind them of what we call the fertilizer credit, by which we mean the nitrates and phosphates in recycled water.”
Olson says the message the district strives to convey is that recycled water is essential to lessening the area’s dependence on imported potable supplies. “Our board of directors has a long-standing commitment to spending public funds to ensure that we continue to provide a reliable supply of water to all our customer base. Recycled water is just one of the ways we feel we can accomplish this.
“In residential areas, we emphasize conservation programs such as low-flow toilets and irrigation classes for residents to help them design and construct water-saving yards and landscaped areas. Because recycled water has been a part of our overall water education program, we’ve had more positive interest from schools. The fact is we live in a desert, and we have to be creative.”
 |
Photo: Walnut Valley Water District |
| Recycled water for cities is critical in land-use and development planning. |
The WVWD sells its recycled water at a 15% discount over potable water, which Hitchman says provides enough income to operate the current system, cover maintenance, and plan for future replacement and upgrades. But it hasn’t been easy. It took 12 years for the district to break even on its recycled water program, and this, says Hitchman, brings up an important point. “You have to look at this as a long-range investment, because it’s not cost-effective in the short term. We didn’t realize when we began that the system was going to take a number of years to pay for itself. Right now we’re covering our costs, and we’ve been able to put some money aside to put into a recycled water development fund, which we’ve used to build the wells and groundwater production facilities to give us some additional reliability in our supply. This is important because the county’s reclamation plant uses a biological process to treat its wastewater, and from time to time there can be upsets that shut the plant down.” According to Hitchman, the district financed the original section of the water system with bonds, but its current policy is pay as you go.
Another critical factor in developing a recycled water system is knowing where your customers are located. “You really have to look at where your potential users are and if you can segregate out the non-potable demand,” says Zimmerman. Projecting land use and development is also important. “It’s a lot easier to put in both systems when the development is being planned, even if the recycled system is not going to be used immediately. Our expansion plans call for going into already developed areas, which means digging up paved streets and traffic control. Unless you look 15 to 20 years out, this kind of a system is difficult to justify on a cost-benefit basis against existing potable water rates.”
What’s up next? Expanding the customer base to include more parks and schools as well as subdivision common areas, and perhaps using recycled water to flush the toilets in the district’s new administration building, which it hopes to showcase as a model of energy efficiency and other environmentally responsible design elements. (As a rule, Los Angeles County doesn’t allow recycled water for flushing toilets except in new buildings.)
“We ought to know better than anyone else what it takes to use recycled water safely,” says Zimmerman. “So we probably should do it in our own building—and see what kind of issues and problems arise.”