Las Vegas gets about 90 percent of its water from the Colorado River, drawn out of Lake Mead behind Hoover Dam, and the remaining 10 percent from groundwater pumped out of aquifers under the Las Vegas Valley.1Las Vegas Valley Water District. Where Your Water Comes From Behind that simple split sits a system of intakes, treatment plants, wastewater recycling, and legal agreements that lets a metro area of more than 1.7 million people live in the Mojave Desert on the smallest Colorado River allocation of any state that uses the river.
Lake Mead and the Colorado River
Nevada’s legal share of the Colorado River is 300,000 acre-feet a year, roughly 98 billion gallons. That figure was set by the Boulder Canyon Project Act of 1928 and confirmed by the U.S. Supreme Court’s 1963 decision in Arizona v. California, which split the Lower Basin’s 7.5 million acre-feet among California (4.4 million), Arizona (2.8 million), and Nevada (300,000).2University of Arizona. Sharing Colorado River Water: History, Public Policy, and the Colorado River Compact Nevada got the smallest share because, in the 1920s, it was sparsely populated and had no real means to divert the water.3National Academies Press. Colorado River Basin Water Management
The Southern Nevada Water Authority, formed in 1991 by seven local water and wastewater agencies, manages that Colorado River supply.4Southern Nevada Water Authority. SNWA Mission Water is pulled from Lake Mead through three intake structures at the lake. Two older intakes sit at elevations of roughly 1,050 and 1,000 feet above sea level. A third intake, finished in September 2015 after years of tunneling under the lake bed, reaches water below 1,000 feet.5Southern Nevada Water Authority. Intake No. 3 A companion facility, the Low Lake Level Pumping Station, can keep drawing water even below Hoover Dam’s “dead pool” elevation of 895 feet.6Las Vegas Valley Water District. How Water Gets to You
How It Gets To Your Tap
Raw water from the lake runs to one of two treatment plants. The Alfred Merritt Smith Water Treatment Facility, operating since 1971, can handle up to 600 million gallons a day. The River Mountains Water Treatment Facility, open since 2002, currently treats up to 300 million gallons a day and is built to expand to 600 million.7Southern Nevada Water Authority. Our Regional Water System Both plants use ozonation, multi-stage filtration, and chlorine disinfection before the water enters the distribution system.8Las Vegas Valley Water District. Testing and Treatment
That system is large. The Las Vegas Valley Water District maintains more than 7,300 miles of pipeline, 84 reservoir basins and tanks holding close to a billion gallons, 55 pumping stations, and over 44,000 fire hydrants. Because much of the valley sits higher than Lake Mead, powerful pumps push treated water uphill to storage reservoirs, and gravity carries it down through distribution mains to homes and businesses.6Las Vegas Valley Water District. How Water Gets to You
How Las Vegas Stretches Its Share: Return-Flow Credits
The reason a 300,000 acre-foot allocation can serve a city this size is recycling. The Boulder Canyon Project Act defines Nevada’s share in terms of “consumptive use,” meaning withdrawals minus whatever is returned to the river. Every gallon of treated wastewater that Southern Nevada sends back to Lake Mead earns a credit that permits an additional gallon to be withdrawn.9Southern Nevada Water Authority. Where Our Water Comes From
About 45 percent of all water delivered in the SNWA service area ends up as treatable wastewater, and roughly 99 percent of that is recycled.10Southern Nevada Water Authority. 2026 Water Resource Plan, Chapter 3 Treated effluent travels back to Lake Mead through the Las Vegas Wash, a roughly 15-mile drainage channel that carries more than 200 million gallons a day.11Las Vegas Wash Coordination Committee. Importance of the Wash Along the way, constructed wetlands filter sediment and contaminants, and 21 weirs slow the flow to limit erosion.12Southern Nevada Water Authority. Las Vegas Wash
The practical effect is that Southern Nevada can pull far more than 300,000 acre-feet from the lake in a given year, as long as its net consumptive use stays under the cap. In 2024, Nevada consumed about 212,000 acre-feet of Colorado River water and returned roughly 244,000 acre-feet to the lake through recycling.13Nevada Current. Nevada Will See Another Year of Colorado River Water Cuts Water used outside, on landscaping, evaporative cooling, or pools, evaporates and can’t be recaptured, which is why outdoor use is the main target of conservation rules.
The Other 10 Percent: Groundwater
Groundwater comes from three major aquifer zones lying between 300 and 1,500 feet below the surface, shielded from contamination by layers of clay and fine sediments. A separate shallow groundwater system within 50 feet of the surface exists but isn’t used for drinking water.1Las Vegas Valley Water District. Where Your Water Comes From During peak summer, groundwater can meet up to 25 percent of the valley’s daily demand.
The valley doesn’t just pump the aquifer, it also banks water in it. Since 1987, the Las Vegas Valley Water District and the City of North Las Vegas have injected more than 360,000 acre-feet of treated Colorado River water into the primary aquifer during periods when Nevada’s allocation ran ahead of demand. The district operates 52 dedicated recharge and recovery wells with a combined injection capacity of about 100 million gallons a day.1Las Vegas Valley Water District. Where Your Water Comes From This underground reserve is held for droughts and emergencies, and it helps prevent land subsidence by keeping aquifer levels stable.14Nevada Current. Las Vegas Serves as Case Study for Groundwater Recovery
Conservation Rules That Shape The Supply
Between 2002 and 2025, the region cut per-capita water use by 58 percent while adding roughly 876,000 people. SNWA’s stated goal is to reach 86 gallons per capita per day by 2035.15Southern Nevada Water Authority. Conservation Initiatives The rules that get it there mostly target outdoor water:
- New developments have been barred from installing grass and spray irrigation since 2022, with exceptions for schools, parks, and cemeteries. A 2021 Nevada law bans the use of Colorado River water on “nonfunctional” decorative grass at commercial properties, common areas, and government sites starting in 2027. The Water Smart Landscapes rebate program has removed more than 250 million square feet of grass since 1999, saving an estimated 203 billion gallons.16Southern Nevada Water Authority. Laws and Ordinances15Southern Nevada Water Authority. Conservation Initiatives
- New golf courses can’t use Colorado River water. Existing courses have water budgets capped at 4 acre-feet per irrigated acre per year, with surcharges of up to nine times the top non-potable rate for overuse.17Las Vegas Valley Water District. Conservation Measures
- Residential pools are limited to 600 square feet of surface area, and new outdoor ornamental fountains are prohibited unless they’re fed by private groundwater or are indoor recirculating features.15Southern Nevada Water Authority. Conservation Initiatives
- New commercial and industrial buildings can’t install evaporative cooling systems.17Las Vegas Valley Water District. Conservation Measures
Mandatory seasonal watering schedules apply across the valley. Since 2002, local jurisdictions have run more than 222,000 water-waste investigations and issued over $2 million in fines.18The Nevada Independent. Is Customer-Based Water Conservation a Drop in the Bucket in Southern Nevada
Water Banked Outside Nevada
Beyond the local aquifer, the SNWA holds reserves across state lines. As of 2024 the authority had more than 2.2 million acre-feet of banked water, about 11 times Nevada’s annual consumptive use of the Colorado River.19Southern Nevada Water Authority. Drought and Shortage
The largest account is in Arizona. Under a 2001 agreement with the Arizona Water Banking Authority, the SNWA has stored 614,000 acre-feet in Arizona aquifers, with capacity to bank up to 1.25 million acre-feet. When Nevada needs the water, Arizona uses banked supplies locally and forfeits an equivalent amount of its own Colorado River water, which the SNWA then takes at Lake Mead. Recovery is capped at 40,000 acre-feet per year under normal conditions. A similar arrangement with California holds 330,225 acre-feet, recoverable at up to 30,000 acre-feet a year. The SNWA also carries credits in Lake Mead itself through “Intentionally Created Surplus,” including 400,000 acre-feet from the Warren H. Brock Reservoir project and nearly 480,000 acre-feet from conservation.10Southern Nevada Water Authority. 2026 Water Resource Plan, Chapter 3
What The Shrinking Lake Mead Means For You
All of this sits against a river in trouble. The SNWA describes the situation as “aridification,” a permanent shift to a drier climate rather than a temporary drought.19Southern Nevada Water Authority. Drought and Shortage Lake Mead hit an all-time low of about 1,040 feet above sea level in July 2022 and, after a modest recovery, has been dropping again. As of mid-2026 the reservoir sat near 1,046 feet, roughly 175 feet below full, with Bureau of Reclamation projections showing a further drop to around 1,015 feet by mid-2027 and 1,011 feet by May 2028.20Fox 5 Las Vegas. Study: Lake Mead Water Levels Projected to Drop 30 Feet by 2028
The Secretary of the Interior issued the first-ever Colorado River shortage declaration in 2021. The Lower Basin has been under a Tier 1 shortage for five straight years, which cuts Arizona’s allotment by 18 percent, Nevada’s by 7 percent (21,000 acre-feet), and Mexico’s by 5 percent. California, which holds senior priority rights under a 1968 federal law, is not required to cut use under a Tier 1 shortage.13Nevada Current. Nevada Will See Another Year of Colorado River Water Cuts If the lake falls below 1,050 feet, a Tier 2 shortage brings an additional 4,000 acre-foot reduction for Nevada.21Colorado River Commission of Nevada. Drought and Colorado River Declared Shortage
For now, Nevada’s actual use has stayed well under its full allocation for years, so the tier cuts haven’t forced rationing at household taps. The combination of recycling, the Low Lake Level Pumping Station, the local aquifer, and the 2.2 million acre-feet in banked reserves is what keeps the water running while the river shrinks.