Columnist Susan Snyder: Mercury level is taking toll

Monday, July 19, 2004 | 8:07 a.m.

Walker Lake's loons could be in trouble.

Make that more trouble.

Tests have shown the birds that rest on the central Nevada lake during migration have high concentrations of mercury in their blood, a U.S. Geological Survey report will say when it is released in about a month.

"The concentration of mercury in the loons on Walker Lake was about twice the North American average," Mike Lico, a USGS scientist, said last week.

Officials also tested water and sediment samples from the east and west forks of Walker River, the main segment of Walker River and Walker Lake. The water didn't show a significant mercury contamination, but the sediment did, Lico said.

Tests in 1996 show the tui chub fish, on which the loons and the lake's Lahontan cutthroat trout subsist, already have higher-than-normal mercury levels. And conditions at Walker Lake are not improving.

The lake that sits 10 miles north of Hawthorne on the east side of U.S. 95 faces a host of problems stemming from a constant drop in water level and a constant rise in minerals and salts called total dissolved solids, or TDS.

A leftover from prehistoric Lake Lahontan, Walker Lake has no natural outflow and receives water only from snow melt into the Walker River. A century of farm irrigation upstream and a yearslong drought have depleted it 140 feet in the past 100 years.

With no fresh water coming in or going out, the TDS level rises dangerously. The TDS level is nearing 17,000 parts per million, which is considered lethal to Lahontan cutthroat trout.

The Nevada Department of Wildlife annually stocks Walker with fishery-raised trout. But 70 percent of last year's stock hasn't survived, and wildlife officials haven't decided whether they will stock trout again in March, Chris Healy, agency spokesman, said Friday.

"Our concentration is keeping the fishery alive. The tui chub have had trouble reproducing. Statistically, they have really not reproduced at all," Healy said. "The mercury is a secondary issue. And it's not going to be any issue if we don't get some water."

Without the tui chub, the loons that rest on Walker Lake's shores and inspire Hawthorne's annual spring loon festival will not have anything to eat.

Wildlife officials counted 1,400 loons on the lake's shores in April 1997 and 1,000 in October that same year. In October 2002 the loons numbered 300 at Walker Lake, said Don McIvor, Nevada director of bird conservation for the National and Lahontan audubon society chapters.

No count was done last year, he said. But mercury is like DDT in that "it gets more concentrated in organisms as you move up the food chain."

Mercury affects a loon's ability to reproduce. But Walker Lake's loons nest in Canada's remote interior, so no one knows whether the mercury is affecting reproduction, McIvor said.

Mercury was widely used in the 19th century mining amalgamation process, and the old mines provide a "perpetual source," Lico said. Carson River delta levels are so high it is a Super Fund site.

As for mercury levels in Walker Lake's trout, officials don't seem overly concerned.

The fish, they say, simply don't live long enough to become lethally contaminated.