The staccato beat of a yellow and blue helicopter’s rotating blades drowned out nearly all other noise as the pilot Joe Ryan tilted the aircraft from side to side and made low circles over power lines west of Ukiah.
It was a clear morning and Ryan and two foresters on board the aircraft were scouring the area for dead and dying trees that could topple into Pacific Gas & Electric transmission lines, triggering outages and potentially igniting fires.
“I think we’ve got a dead one here,” Ryan said into a microphone, relaying instructions to Amy Rowe and Chelsea Michael, foresters with Western Environmental Consultants Inc.
The team, including Ryan of A&P Helicopters, has been hired by PG&E to survey its lines across several North Coast counties, where the state’s prolonged drought, insect infestation and disease have all taken a heavy toll on forests.
Though abundant rainfall this winter banished the drought, the dangers presented by the state’s ravaged forests are higher than ever, according to utility officials, firefighters and foresters. Statewide, an estimated 102 million trees have died during the drought and its immediate aftermath, with many millions more expected to succumb in the next few years.
“No amount of water was going to bring back those trees,” said Heather Williams, a spokeswoman for Cal Fire, the state forestry and firefighting agency.
As a result, PG&E, which annually inspects all 134,000 miles of its overhead power lines in northern and central California, last year added a second patrol on some 68,000 miles of line located in high fire hazard areas, said company spokeswoman Linsey Paulo. This year, it plans to patrol 73,000 miles of line a second time.
The hot spot for dead trees in California remains the Sierra Nevada range, where vast swaths of red and brown trees cover mountain sides. Some 76 million trees have died in the ten worst hit counties, including Amador, Calaveras, El Dorado, Fresno, Kern, Madera, Mariposa, Placer, Tulare and Tuolumne, according to the state’s Tree Mortality Task Force, which includes local, state and federal agencies and utility companies such as PG&E. The tree mortality data is based on the U.S. Forest Service’s annual aerial detection surveys.
While not among the hardest hit, Northern California counties also have seen spikes in tree mortality.
Forest Service survey maps show the highest concentrations of dead trees in Mendocino and Lake counties are in the Mendocino National Forest. Sonoma County has several concentrated pockets of dead trees just west of Cazadero and south of Lake Sonoma, according to state data.
In fire prone Lake County, the Boggs Mountain Demonstration State Forest is among the prime problem areas. It was hit by a beetle infestation before the Valley fire swept through in late 2015, turning the forest into a graveyard of blackened firs and pines. Trees in the area that were not burned remain under attack by the pests. Water-starved conifers are more susceptible to pests and diseases because they are unable to produce sufficient sap to ward off the invaders.
The wave of tree deaths has not been as intense in Mendocino County, but it’s still taken a toll, with some 330,000 dead trees recorded during Forest Service aerial surveys since 2010, according to Cal Fire. The highest count was in 2015, with 133,000 trees.