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Pipe being lifted by crane as workers look on

Horizon Lateral

Like the low lake level pumping station at Lake Mead, which protects Southern Nevada's access to our primary drinking water source, the Horizon Lateral will protect our ability to reliably deliver water to current and future residents and businesses in this region of the valley.

Forty percent of Southern Nevada's drinking water is delivered through a large water pipeline known as the South Valley Lateral. Completed in the 1990s, this pipeline was built before much of the current City of Henderson existed. Now it supports nearly a million people in the southern part of the valley.

The Southern Nevada Water Authority is planning to build a second pipeline to convey water throughout the south end of the valley. Called the “Horizon Lateral,” this project will help ensure reliable water service for Southern Nevada.

If major repairs on the South Valley Lateral are needed, or a system outage occurs, the Horizon Lateral will help maintain water deliveries. Both pipelines will work together to ensure our water system remains one of the most reliable in the nation.

Components of the project

The project includes the installation of about 30 miles of large pipe up to 10 feet in diameter (much larger than the pipelines or water mains you might find in the street outside your home).

The Horizon Lateral project also includes construction of:

  • Two pumping stations
  • A 40-million-gallon water storage reservoir
  • Six rate-of-flow control stations to interconnect with the existing water distribution system

Routes under consideration

Two routes are under consideration:

  1. The "south alignment" would be constructed through mostly undeveloped areas of the valley, including tunneling underneath a portion of the Sloan Canyon National Conservation Area. This is the Water Authority’s preferred alignment, as it would avoid significant disruption to streets in Henderson neighborhoods and economic impacts to the business corridors.
  2. The "north alignment" would require installing the pipeline in densely developed portions of Henderson, including some of the busiest streets and thoroughfares in the region such as Horizon Ridge, St. Rose, and Paseo Verde parkways, Cactus Avenue and Mission Drive. This alignment will require temporary road closures and traffic detours, as well as temporary closures of various parks and trails. Along with the heightened risk of construction in a heavily developed urban corridor, the "north alignment" will increase project costs by approximately $200 million.

Both alignments require federal rights of way to be issued by the Bureau of Land Management, and are subject to environmental review and permitting processes. The final route will be determined pending the permitting process.

Horizon Lateral 3D aerial map showing two proposed routes

Frequently asked questions about the Horizon Lateral

Yes. Existing water deliveries to Henderson and the south valley are provided by a single transmission line known as the South Valley Lateral, which delivers nearly 40 percent of Southern Nevada's drinking water. When built, the new Horizon Lateral will boost system reliability by adding a dual feed for the area and protecting water delivery for nearly a million existing customers.

Municipal water systems add redundancy in the form of dual feeds to improve reliability of water delivery – so that when customers turn on the tap, that demand is consistently met. Moreover, redundancy enhances the Southern Nevada Water Authority’s ability to prevent and recover from emergencies such as pipeline leaks and outages.

The need for redundancy was highlighted in 2017 when the South Valley Lateral was temporarily shut down for emergency repairs, requiring the Water Authority and the City of Henderson to temporarily reconfigure water delivery operations to continue meeting customer demands.

While all customers remained in water service, the event emphasized the need to develop additional transmission facilities in this portion of the community to help ensure system reliability.

Water is currently delivered to Henderson and the southern portion of the valley via the South Valley Lateral. The transmission pipeline spans 27 miles.

The project includes 30 to 40 miles of tunnel and trenched pipeline (four to ten feet in diameter), seven to eight miles of tunneling, two pumping stations, a 40-million-gallon reservoir, and related facilities.

Estimates are in the range of $1.4 to $2 billion.

The Horizon Lateral will be funded locally through regional connection fees paid by developers and the Water Authority’s infrastructure and commodity charges paid by all water users in the community.

There are two routes under consideration. The preferred "south alignment" largely minimizes public impacts by tunneling underneath the Sloan Canyon National Conservation Area.

The "north alignment" would be constructed within some of the area's busiest streets and thoroughfares. This alignment will require temporary road closures and traffic detours, as well as temporary closures of various parks and trails.

Multi-agency participatory workshops were used to develop the "south and north alignment" routes and facility configurations. Participants included members of the Southern Nevada Water Authority, Las Vegas Valley Water District, the cities of Henderson and North Las Vegas and the consultant team from Black & Veatch. Representatives from the U.S. Bureau of Land Management attended portions of several sessions.

No. Both routes are subject to regulatory, environmental and permitting reviews, as well as feedback by the Bureau of Land Management (BLM). The permitting process is expected to continue over the next few years.

The Southern Nevada Water Authority has recommended the preferred "south alignment" to the BLM, as it substantially reduces public impacts. The Water Authority also has significant experience tunneling under federally protected land from constructing the Third Intake and Low Lake Level Pumping Station.

No. The Horizon Lateral will increase system reliability for nearly a million existing customers, ensuring that when they turn on the tap, the demand is consistently met. Working in tandem with the existing South Valley Lateral, the Horizon Lateral will ensure that Southern Nevada's water system continues to deliver and meet the current and future water needs of our community.

Absolutely. The Southern Nevada Water Authority continues to implement one of the nation’s most comprehensive and innovative conservation programs. The community’s support for water conservation has saved hundreds of billions of gallons of water since the western regional drought began in 2000. As a result, Southern Nevada uses less water today, per person, than 20 years ago.

Yes. In September 2019, the Southern Nevada Water Authority Board of Directors convened the Integrated Resource Planning Committee (IRPAC) to evaluate and make recommendations on long-term planning efforts. Made up of members who represent small business, gaming, homebuilders, economists, ratepayers and environmental interests, the 11-member citizens committee met seven times between Oct. 30, 2019, and March 4, 2020.

The Horizon Lateral was included in IRPAC’s recommendations for the Southern Nevada Water Authority's long-term capital improvement projects. A high level of public involvement will continue through the environmental, regulatory and permitting reviews as well as through design and construction of the Horizon Lateral.

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