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Southern Nevada Water Authority

Consumptive Use

Consumptive Use

Water used outdoors falls under the
consumptive use category because it is
often lost to evaporation.

While nearly all water used indoors can be recycled, water used outside often can't because of evaporation. This also is known as "consumptive use."

Consumptive use is the water that is actually consumed and not returned to the immediate water environment. It's the portion of water that evaporates, is used in products or crops or is consumed by people or livestock.

Consumptive Use and Return-Flow Credits

In 1928, the Boulder Canyon Project Act determined the distribution of water to Colorado, New Mexico, Utah, Wyoming, Arizona, California and Nevada. The compact limited Nevada to 300,000 acre-feet of water per year.

The Bureau of Reclamation, which is responsible for keeping track of Colorado River water, deducts any water returned to Lake Mead (return-flow credits) from Nevada's river withdrawals. This returned water includes water from sinks, showers, water smart car washes and other sources that send the water through pipes to the wastewater treatment plant, where the water is treated and returned to the lake.

Consumptive use water, such as landscape watering, doesn't qualify for return-flow credits because it is not returned to the system.

Southern Nevada's water use is based on "net" consumption rather than "gross" withdrawals. Because Southern Nevada returns about 200,000 acre-feet of water to the Colorado River system each year, it receives about 200,000 acre-feet of return-flow credits. This allows us to withdraw nearly 500,000 acre-feet of water each year, stretching our original allocation.

Save Water Where it Counts

Approximately 60 percent of Southern Nevada's water is used outdoors, meaning it doesn't earn return-flow credits and is counted against our Colorado River withdrawals. Because of this, the conservation rebates and programs of the Southern Nevada Water Authority (SNWA) focus on reducing outdoor water uses such as landscape watering.

The fact is, the water we use inside our homes, businesses and hotel rooms has much less impact on our community's water supply than the water used outside because water used indoors is recycled and re-used. But that's not to say that water should be left running while brushing your teeth or shaving. It requires a great deal of energy to treat and deliver the water to the Las Vegas Valley.

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