The water used by residents and visitors in the Las Vegas valley goes through quite a journey during use, often only to be returned to the Lake and re-used again and again. The majority of water used in the urban areas of southern Nevada begins its journey in Lake Mead – a reservoir that can hold a large supply of water. In fact, when the lake is full, it holds twenty-eight million-acre feet of water! This seems like more than enough water, but Nevada is limited to only 300,000 acre feet per year. This allotment is based on negotiations that happened almost 100 years ago when the seven states within the Colorado River Basin decided how much water would be available to each state. (A share of the Colorado River is also committed to Mexico.) As Nevada continues to grow, managers and users have to make every drop count.
When the reservoir is full, it holds twenty-eight million-acre feet of water.
Photo: Lake Mead circa 2001
Imagine a single drop of water. That drop might be in our water cycle for years. As water leaves the lake through huge intake pipes, it moves to one of two drinking water treatment centers to be cleaned. All of the water entering Las Vegas Valley travels via a four mile tunnel that runs through the River Mountains before entering one of many pumping stations at the Las Vegas Valley Water District service area. The pumping stations then push the water to homes and businesses. This entire process is hard work – it is estimated that up to 14% of the energy used around the United States is used treating and pushing water around.
Faucets and showers each account for 11% of single family residential water use, while washing machines account for 16%. Toilet use accounts for 24%.
Once water arrives at our homes and businesses, its journey is still not complete. We use water for all kinds of things: cooking, cleaning, landscaping, filling up our pools and even flushing the toilet. More than half of the water used in Las Vegas goes to outdoor landscapes. A majority of landscaping water is consumed by plants. Water that drains away from landscaping plants is harder to collect and get safely back into the system. This water often evaporates, seeps into the ground or runs into storm drains eventually finding its way into the Las Vegas Wash and then Lake Mead. This water often picks up contaminants along the way, which are carried to the lake.
Luckily, most of the water we use indoors is recycled and re-used. Water that goes down an indoor drain enters back into the system after going through a carefully engineered treatment and cleaning process before re-entering Lake Mead. Six thousand miles of underground pipes move the used water to one of the four wastewater treatment facilities. In fact, every day, about 180 million gallons of raw sewage is treated in the Las Vegas valley. It takes about nine hours in the average plant to purify the water of pollutants. Ninety percent of the cleaned wastewater is released into the Las Vegas Wash where it mixes with urban run-off while making its ten-mile journey back to Lake Mead. The Wash flows through the Clark County Wetlands where settling ponds and vegetation help remove suspended sediment and some contaminants from the water.
Water that goes down an indoor drain enters back into the system going through a carefully engineered process for treatment and cleaning before re-entering Lake Mead.
Remember those 300,000 acre feet of water allotted to Nevada from Lake Mead? Well, one acre-foot of water supplies a little more than two average Las Vegas homes for a year. Simple math shows us that is just not enough water. But because the valley receives water credit for every drop it puts back into the Lake, the water supply for the residents and tourists’ is easier to manage and keep balanced. Decisions residents make about how and where to use water have big impacts on the amount of water returned to the lake, the cleanliness of the water in the lake, and the amount of water we have for the future.
A drop of water takes quite a journey from the mountains in Colorado, to Lake Mead, and eventually into our homes. We use it in in our showers, toilets, washing machines, even kitchen sinks. After use, it heads off to be cleaned before it ventures back into Lake Mead. This water needs to go through a cleaning process called wastewater treatment, and luckily, this process is going high tech for ultimate results maintaining clean Lake Mead water.