Nearly a week of rain came and went without causing major soil erosion in the Rim fire area, the Stanislaus National Forest reported.
Employees conducted “storm patrols” to see whether the rain sent soil into streams or damaged the roads that lace the woods.
“So far, it looks like all of our hard work has paid off,” said Rusty LeBlanc, road maintenance engineer for the forest, in a news release. “We have been able to keep the roads clear using our own equipment with very little work to do (after storms).”
The fire, the largest in the Sierra Nevada’s recorded history, spread across 257,314 acres in the forest, Yosemite National Park and private land from August to October.
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An initial report said 7 percent of the land within the Rim perimeter had severe soil damage, putting it at high risk of erosion during storms in the months that followed. An additional 37 percent had moderate damage, meaning that the soil structure stayed intact and could buffer raindrops. The rest had light damage or did not burn at all.
Soil and other debris can end up in reservoirs, including Don Pedro, owned by the Modesto and Turlock irrigation districts, and San Francisco’s system upstream on the Tuolumne River. Erosion also can damage roads needed for salvage logging, replanting and other fire restoration work.
The forest staff reported that the fire zone has received 6 to 12 inches of rain since fall, much less than average. Close to half of the rain fell in a five-day stretch this month.
The forest staff had prepared for rain by grading roads, repairing culverts and taking other steps against erosion.
“Watershed effects after fires are real,” said Scott Tangenburg, deputy forest supervisor. “They’re documented, and we’ve done everything we can to prepare for them.”
Carol Russell, director of the Don Pedro Recreation Agency, said the recent rain brought some debris into the reservoir, but it was no greater than what comes down in years without a major fire.
Water quality effects are not a major concern at Don Pedro, but the branches and other debris can endanger boaters. The recreation staff catches the material with a pair of portable booms where the river enters the reservoir.