The massive, still-burning Rim Fire will torch a substantial amount of the Turlock Irrigation District's watershed, though impacts to TID operations are still projected to be minimal.
“We'll hit 25 percent of the watershed (burned) before all is said and done,” said Wes Monier, TID Strategic Issues and Planning Department Manager.
The Rim Fire has torched 235,841 acres along Highway 120, near Yosemite National Park, according to Cal Fire. The blaze is now 75 percent contained, thanks to increasing humidity and light showers. The fire should be completely contained by Sept. 20, Monier said.
A massive 4,559 fire personnel have responded to the Rim Fire, including some Turlock firefighters. Flames have torched 111 buildings, and 5,506 more are considered threatened.
The Rim Fire has greatly impacted operations at the City and County of San Francisco's Hetch Hetchy Reservoir, upstream of TID's Don Pedro Reservoir. Hydroelectric generators have been stopped, as fire threatens transmission lines, and high levels of ash have raised concerns about water quality.
TID expects some impacts from the fire, as rains will eventually wash burned logs into the Tuolumne River and Don Pedro Reservoir, necessitating clearing operations. But what likely won't change is the total amount of water that TID receives from the watershed, according to Monier.
TID recently spoke with Norman Crawford, who developed the watershed model used to project runoff from the Tuolumne River watershed.
“He seemed to think that the total volume of water over the year … really won't change,” Monier said. “But what it will change is the rate it comes off.”
Water could arrive into TID reservoirs in a spiky fashion, Monier said, without foliage to absorb water or shade melting snow.
TID and the CCSF plan to meet with Crawford in the coming weeks to take a more detailed look at impacts stemming from the Rim Fire, Monier said.