Las Vegas Sun

November 18, 2017

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How deep is safe?

Lake Mead is both the source of the region's drinking water and the receptacle for the end product.

"It's been a huge public perception issue over the years," said Doug Karafa, program administrator for the Clean Water Coalition.

"There probably never would be a health issue, but it's been a huge perception issue."

As Las Vegas grows, so does the amount of wastewater, which is treated and sent down the Las Vegas Wash into Lake Mead.

You flush. You shower. You wash the dishes.

It all goes down the drain and to a sewage treatment plant. There the solids are removed and the water is treated well enough to be used for irrigation or in a decorative water fountain, but not well enough to drink.

Every day 180 million gallons of the "treated wastewater" pour into the wash, which flows into Lake Mead, where the huge volume of water further dilutes any remaining contamination.

Two miles downstream from the mouth of the wash, two huge intake pipes pull the lake water in and carry it to a treatment plant, where it is cleansed and becomes drinking water.

While there is not a contamination problem now, that could change as the volume of treated wastewater increases to 300 million gallons a day or more, Karafa said.

He said the "wastewater flows are going to double in the next 20 years."

Under the umbrella of the Clean Water Coalition, the Clark County Reclamation District, Henderson and Las Vegas, which all contribute to the wastewater stream, are embarking on a $625 million project to build a pipe to send the treated wastewater deep into Lake Mead, avoiding the wash all together.

The wastewater would be piped to a point near the Boulder Islands, about two miles downstream of the water intakes, and released about 300 feet below the lake's surface. A less favored alternative would be to pipe the wastewater into Las Vegas Bay, where the wash comes into the lake.

The plans are being evaluated -- an environmental impact statement was printed last month -- and water officials hope to have a system built by 2012.

Is it safe to put that much wastewater that much closer to the intake pipes that send water into Las Vegas to be treated and made drinkable?

Officials say that the lake water piped to the Southern Nevada Water Authority's plant is treated to be above state and federal standards for drinking water.

"We have one of the most highly advanced water treatment systems in the world," Water Authority spokesman Vince Alberta said.

The Clean Water Coalition's study of the plans also contends that piping the wastewater deeper into the lake would further dilute it.

Bill Shepherd, operations manager for the Reclamation District's 600-acre treatment plant, said the water that leaves the plant and goes into the wash is of "near drinking-water quality."

While district managers don't recommend swimming in it or drinking it, the water is of much higher quality than the water that flows down the wash from urban runoff, which includes the detritus of urban living -- from animal waste to motor oil.

Shepherd recently showed off the Reclamation District's treatment system, which includes more than a dozen mechanical, biological and chemical steps to separate waste from water and control odors escaping to the surrounding residential community.

Solid waste is separated from the liquid and is trucked off to the landfill at Apex.

The treated wastwater then either goes to the wash or is used in fountains or to water golf courses or parks.

The treated wastewater is actually a resource to Southern Nevada, as real as the water in the Colorado River that sustains 90 percent of the region's drinking water needs. For every gallon of wastewater that makes it down residential or business drains, through the treatment process, down the wash and back into the lake, the Southern Nevada Water Authority gets to take another gallon of water out as a "return flow credit."

Karafa said one of the beneficiaries of the new discharge system would be the wash itself, a desert oasis for plants and animals in which flows would return to levels that were last seen in the 1960s.

The project would cut 75 percent of the current flow in the wash, which would be good for the sprawling, park-like feature, Karafa said.

"It will get a lot of the effluent out of the wash," he said. "We'll make that system work again."

Downstream from the lake, users of Colorado River water are watching the project carefully but have no specific criticisms, at least so far.

"It all gets into Lake Mead eventually, so that isn't changing," noted Jeff Kightlinger, general counsel for the Metropolitan Water District of Southern California. The district supplies nearly 25 million people with water from several sources, including the Colorado River.

"We're doing a technical analysis to see if they (the Clean Water Coalition) are doing it the best way possible."

The water district had representatives on advisory committees as the project moved forward, Kightlinger said.

"They've been working with us to make this as clean as possible."

Herb Guenther, director of the Arizona Water Resources Department, said he doesn't see a downside for his state, which also gets water from downstream.

"It's probably a good move for Nevada, and I don't see any significant downside for others."

Launce Rake can be reached at 259-4127 or [email protected]

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