INCLINE VILLAGE -- The sickly brown needles and leaves of some trees along highways on the Nevada side of Lake Tahoe have residents and agencies concerned about the cause.
The extent of the problem isn't yet known, but several Nevada agencies are investigating the situation.
Some blame the Nevada Department of Transportation's wintertime snow and ice roadway treatment, pointing to an apparent lack of similar damage on California highways and on county-maintained roads.
The state's approach includes remote monitoring of road and air temperatures, and wetting the road with a brine solution to keep snow from freezing. When temperatures drop low enough, sand or a sand-salt mixture are applied to prevent freezing. When the weather improves enough, the roads are cleaned with sweepers and plow trucks.
But staff members from several agencies say there is a wide spectrum of causes for this sort of tree damage, including drought and insect assaults, as well as wintertime salt treatments that keep roads from freezing and becoming a safety hazard.
John Christopherson, a regional director with the Nevada Division of Forestry, says that salt damage to roadside plants has been around for years, and is to some degree an unavoidable part of ensuring public safety on the roads.
"It's a problem that's been kicking around for a long time, all over the country," Christopherson said. "This year it seems to be more visible than in the past. Right now it's pretty eye-popping and very visible."
Christopherson said he and state forester Tim Rochelle are researching possible causes of the evident tree stress for the Tahoe Regional Planning Agency, and expect to complete a report by next month.
"We're just doing a literature search for now," Christopherson said. "If TRPA can come up with the money, we can send tree materials to a lab for chemical analysis."
Thor Dyson, state transportation assistant district engineer, said he first began to worry that the roadway treatments might be hurting some trees last fall.
"We obviously need to reassess our operations," Dyson said. "We'll take a real close look at our anti-icing operations. If it does come down to us being the main problem, we'll explore other options."
Dyson said keeping roads open during the winter in the basin requires a delicate balance between the environment, public safety, and operational logistics, and said the state's extensive environmental improvements shows its commitment to the environment.
"By changing over to the remote monitoring system, and going from rock salt to brine, we've managed to reduce the amount of salt and dust that goes into Lake Tahoe," Dyson said. "We were one of the first states in the country to do this, although it has been used for at least 20 years in Europe."
Christopherson said a literature search has turned up a 1991 state transportation study of similar damage to trees, when rock salt and hefty applications of sand were used to keep basin roads safe.
It isn't clear if the problem exists in California. Repeated calls to California's transportation department, CalTrans, have not been answered.
But Rob Erlich of the Lahontan Regional Water Quality Control Board says he's noticed similar damage along parts of Emerald Bay, but isn't sure what is causing it.
"I've noticed a lot of dead or dying trees in Nevada," Erlich said. "Since then, I've kept my eye on it in California, too."
Erlich said salt damage can resemble drought damage, and pointed out that the last two years were some of the driest in Nevada history.
"Nevada also gets less precipitation than California does," Erlich added.