Dye to trace sewage flow in Lake Mead

Friday, Sept. 10, 2004 | 8:56 a.m.

Boaters, swimmers, even airplane pilots and passengers may notice a patch of bright red in Lake Mead next week when scientists put a dye into the lake to study how water flows and mixes.

The Clean Water Coalition, composed of the Clark County Water Reclamation District and Las Vegas and Henderson, has been studying the lake for a better place to discharge treated waste water from the Las Vegas Valley's three sewage treatment plants, coalition administrator Douglas Karafa said.

"Some people may see a big red stain in the middle of the lake," Karafa said. "It's a completely harmless dye."

The dye is similar to food coloring and will not stain or harm swimmers, boats or drinking water, he said.

Scientists will release the dye at the surface and 75 feet deep under the lake's surface and then will track the currents. Water samples will be collected by researchers so concentration and distribution of the dye can be recorded as it flows through the lake.

Sunlight destroys the dye in one or two days.

The extended drought affecting the Southwest has changed how water flowing from the Colorado River mixes in Lake Mead, an important thing to monitor because of water treatment.

Las Vegas, Henderson and the county treat sewage to near drinking water quality and then return it to the lake through the Las Vegas Wash. Karafa said that as the lake's level continues to drop and treated waste water increases, a new location for the discharge is necessary.

In February a citizens committee including local, California and Arizona representatives recommended that the discharge point be located near the Boulder Islands in the lake.

The dye study will also help verify a year of computer models produced by scientists, Karafa said.