Introduction

Chula Vista is in Southern California, centrally located between downtown San Diego to the north and the US-Mexico border to the south. Established as a city in 1911, Chula Vista is now the second-largest city in San Diego County, with a population of 250,000 and an area of about 50 square miles. Chula Vista has an agricultural past and was once known as the “Lemon Capital of the World.” Much of its land was used for ranching dating back to the early Spanish settlers. Beginning in the 1980s, the ranch land was sold and built into master-planned developments, some of which are still growing today.

Chula Vista has a Mediterranean climate with an average yearly rainfall of about 10 inches. It is encircled by four bodies of water: the Sweetwater River and Reservoir to the north, the San Diego Bay to the west, the Otay River to the south, and the Otay Reservoir to the east. Both the Sweetwater and Otay Rivers are mostly dry; they are primarily used as spillways for the reservoirs. The lower San Diego Bay is a coastal salt marsh, one of the last remaining Southern California coastal marshes. Along the Bay are the San Diego National Wildlife Refuge, the bayside park and marina which are undergoing redevelopment, and salt ponds used for salt extraction by South Bay Salt Works, the second-oldest business in San Diego County.

Supply Challenges

Getting water to Chula Vista is a complex process of buying and selling water among a number of water authorities. Large aqueducts bring 13% of San Diego County’s water from Northern California via the State Water Project, and 72% from the Colorado River. This water is purchased by the Metropolitan Water District of Southern California (MWS), which is based in Los Angeles. The MWD sells water to the San Diego County Water Authority (SDCWA).

Water distribution within Chula Vista is a tale of two authorities. The SDCWA sells water to both the Sweetwater Authority, which supplies water to west Chula Vista, and to the Otay Water District, which supplies water to east Chula Vista. The duel-authority system is a challenge for the City because there are some differences in the water supplied by each authority. The Sweetwater Authority supplies 70% local water – particularly groundwater – and 30% imported water. Otay Water District is far more reliant on imported water – 85% of its supply is imported – but its local supply is entirely from recycled water. In east Chula Vista (Otay Water District’s service area), new developments are required to install purple pipelines to supply recycled water for non-potable use, especially for irrigation.

The City of Chula Vista is proactive about conservation and appears to be managing water demand well, especially in response the California’s historic drought. In 2015 the City reported lower water use than both the Sweetwater Authority and the Otay Water District: 77 gpcd, 91 gpcd, and 121 gpcd respectively. Both water authorities cover areas outside Chula Vista, so this indicates that the City is managing its water more efficiently than other communities the water authorities service. While Chula Vista’s demand-side water management is relatively under control, its supply-side management is more unpredictable.

The primary water challenge for Chula Vista is its dependence on imported water. The pressure to develop more local water sources has become more urgent as drought and other environmental factors threaten the Colorado River and the City’s other water sources in Northern California. In an effort to diversify the City’s water supply, both the Sweetwater Authority and the Otay Water District have plans to increase groundwater extraction. The Sweetwater Authority recently built five new wells and expanded its brackish water desalination plant, which extracts 18,000-year-old groundwater. This “fossil water,” although cheaper to produce than imported water and arguably better quality, is ultimately problematic because it is not rechargeable.

A Three-Part Solution

To address Chula Vista’s concern with reducing its dependence on imported water I am proposing a package of three solutions to diversify the City’s water portfolio. First, Chula Vista should extend its recycled water network to the west side of the city and retrofit its existing facilities to produce potable water. Second, it should ensure its existing groundwater wells are operating sustainably before constructing new ones. And third, the City should continue promoting and incentivizing water conservation programs.

Recycled Water

To further integrate recycled water into its water supply Chula Vista has three options, and ideally the City in conjunction with both water authorities would pursue all three.

The first option is to install a recycled water system in the Sweetwater Authority service area like that in the Otay Water District service area. According to the Sweetwater Authority’s 2015 Urban Water Management Plan, they have already evaluated eight recycled water system alternatives, including building a new recycled water plant that would be constructed by Sweetwater and the City, and a recycled water supply from the City of San Diego’s South Bay Water Reclamation Facility (SBWRF). Some of the wastewater from Sweetwater’s service area is already treated at the SBWRF but is sold to the Otay Water District because unlike Sweetwater, it has the necessary recycled water infrastructure. Installing a recycled water system in west Chula Vista would ensure better consistency in the water supply across the whole city.

The second option is to expand Otay Water District’s reclamation facilities for treatment for potable use. Otay Water District currently treats recycled water to the level acceptable for non-potable irrigation uses for parks, schools, highway medians, etc. The Otay Water District could partner with the City of Chula Vista to fund the construction of additional treatment facilities so that the recycled water it produces can at least be used for indoor non-potable uses like flushing toilets, but ideally the treatment facilities would include a multi-step purification process to treat recycled water to drinking water standards.

The third option is to tap into the planned Pure Water San Diego program. This is a multi-year program that will provide a third of the County’s drinking water supply locally by 2035. A Pure Water facility is planned for the SBWRF, which both Sweetwater and Otay are already connected to. The City of Chula Vista already has a stake in this project: it has contributed $5.6 billion to the project using some of the City’s sewer funds. Tapping into Pure Water San Diego is the option that would require the least amount of additional infrastructure, but it ultimately still leaves Chula Vista dependent on imported water, albeit from a closer source.

In its 2015 Urban Water Management Plan, the Sweetwater Authority said that implementation of recycled water within its service area was cost prohibitive. There have been financial developments since then that I believe are cause for Sweetwater to reconsider. The City of Chula Vista just last month approved the Bayfront redevelopment project, which will bring in about $1.1 billion. Through a partnership with the City, Sweetwater could possibly leverage some of that revenue to construct the recycled water system. Considering how heavily the City invested in Pure Water San Diego, it is not unreasonable to predict that it would be willing to invest in a robust recycled water program of its own.

Groundwater

Groundwater, as long as it is rechargeable, is a viable alternative to imported water for Chula Vista. The Sweetwater Groundwater Basin was not identified by the Department of Water Resources as being in overdraft condition. Because both the Sweetwater and Otay Valley Basins are categorized as “very low priority” by the State, neither authority is required to form Groundwater Sustainability Agencies or to draft Groundwater Sustainability Plans (GSP) in compliance with the State’s 2014 Sustainable Groundwater Management Act.

Nevertheless, according to the Sweetwater Authority Strategic Plan FY 2017-18, the US Geological Survey is scheduled to conduct groundwater studies this summer to understand the basin and to support the development of a GSP; preparation of the GSP will begin in January 2019. Otay Water District does not currently operate any wells, but its Rancho del Rey Well is planned for 2030 and although it appears to be economically viable, little is known about its recharge sources. If Otay Water District is serious about treading into the groundwater business, it too should prepare a GSP.

Conservation

Chula Vista has a number of conservation strategies for demand-side water management and the City’s reasonably low water use is a testament to their success. Since 2003 the City has required Water Conservation Plans for all new major development projects. New developments are required to use recycled water where available, which right now is just within the Otay Water District service area. The Landscape Conservation Ordinance went into effect in 2010 and requires that any new or rehabilitated landscapes are designed using a water budget to help encourage outdoor water conservation. The City recently adopted an ordinance that requires new residential development to provide a stub-out for a clothes washer graywater outlet and a stub-out for a graywater irrigation system.

Outdoor irrigation for landscaping needs accounts for about 60% of overall water use in homes, so the City collaborates with the Sweetwater Authority and the Otay Water District on conservation programs. WaterSmart San Diego offers incentives and rebates to help people implement water-saving improvements at little to no upfront cost. The NatureScape program helps residents implement sustainable landscaping practices through free community workshops and technical assistance.

In 2016 the City published its Water Stewardship Plan to assess near and long-term opportunities to enhance water efficiency and to reuse graywater, stormwater, and wastewater for community and municipal use. The City could start by retrofitting its own facilities, like converting the mostly turf landscaping at City Hall to demonstrate the water-saving measures the City is proposing.

Conclusion

Regarding water supply and management, Chula Vista is not in a state of crisis, but the City and both water authorities have room to improve. By promoting conservation and smart landscaping the City can reduce water demand. By completing its recycled water network and pairing it with sustainable groundwater, Chula Vista can meet its goal of reducing dependence on imported water and achieving a higher degree of water sovereignty.