Source of carbon in Lake Mead subject of study

Wednesday, Aug. 15, 2001 | 10:12 a.m.

The Southern Nevada Water Authority will consider a proposal for a $50,000 study of "dissolved organic carbon" in Lake Mead, the source of most drinking water for the region.

The study would help identify the source of the carbon and ultimately control potentially dangerous byproducts.

UNLV chemist Spencer Steinberg, who would do the research, said the study would help government agencies better manage the overall condition of the lake and could uncover the impact of a huge algae bloom this year.

The carbon, which can be produced as a byproduct of the decay of algae and other plant materials, can combine with other chemicals to produce chloroform and other materials potentially harmful to human and other life.

Dave Rexing, Water Authority research and development manager, said the levels of those contaminants in the lake and drinking water is well below federal limits, but his agency wants to identify the source of the dissolved carbon with a goal of eliminating the unwanted chemicals.

"We're well below any standards, but let's shoot for zero, if that's possible," Rexing said. "Knowing the source of the carbon allows us to take the next step."

Steinberg, a UNLV chemist for about 11 years, said the study will help identify the sources of organic chemicals in the water.

"Management is the most important element here," he said. "All of these sorts of studies are important. It will help in the long run to give us another kind of management tool for the water."

Rexing said the authority does not believe that the algae produced much of the carbon. The source could be from other areas of the Colorado River or its tributaries, including the Muddy and Virgin rivers, Rexing said.

Another source could be the Las Vegas Wash, through which runoff, groundwater and partially treated waste water flow into Lake Mead, he said.

Larry Paulson, a former UNLV biologist and community activist, said the source for both the algae and dissolved carbon is likely the wash. Paulson has criticized authority policies for allowing too much waste water -- treated and otherwise -- into the lake.

"Certainly efforts ought to be made to control those dissolved organic compounds," he said. "Identify the source and cut off the source."

While the dissolved carbon and related acids are not themselves dangerous, chlorine used to treat water reacts with the organic compounds to produce potentially dangerous byproducts, Rexing and Steinberg said.

"As a public utility, we add chlorine to the water," Rexing said. "It is a powerful chemical and can form other compounds ... Some of those byproducts tend to be unhealthy."

Those byproducts, including chloroform, a carcinogen, can be difficult to remove in water processing, Steinberg said.

Rexing said the effort to study the carbon is one piece of a very large and complex puzzle of how the rivers and lake work as a system. The study will be part of a much larger authority-funded effort to study the processes involved in the lake.