Scientists still seek source of lake algae

Thursday, Nov. 1, 2001 | 9:34 a.m.

The cause of the large algae bloom that covered parts of Lake Mead this summer may never be known, officials said today.

A report on the bloom was presented today to the Lake Mead Water Quality Forum, a group of federal, state and local officials responsible for protecting water quality.

Water quality officials want to prevent another such bloom and are working toward that goal.

The Las Vegas Valley's three major sewage treatment plants -- Clark County, Las Vegas and Henderson -- will remove more than 90 percent of phosphorous, a nutrient that nurtures algal blooms, from all discharges throughout the year.

The three treatment plants dump an average 150 million gallons a day of wastewater into the Las Vegas Wash, which flows into Lake Mead. Although a team of scientists couldn't explain why the algae bloomed throughout the summer, phosphorous is suspected in nourishing the green-celled growth that blanketed Lake Mead April to July.

Henderson had been allowed to discharge its phosphorous into the wash from November through March, plant manager Michael Neher said. Henderson recycles its treated sewage.

Local water agencies plan to study runoff from the surface of the valley and measure chemicals, including phosphorous, that come from lawn fertilizers and other sources.

The Clark County Regional Flood Control District will collect routine samples from the wash and the lake, district engineer Kevin Eubanks said.