Update, 5:45 p.m. Wednesday, Sept. 12: Incident commanders say the Delta Fire has now burned just under 54,000 acres -- about 80 square miles, or roughly the size of Oakland -- and is 15 percent contained.
With the fire in the Interstate 5 corridor at least partly contained, limits on travel along the highway were relaxed Wednesday. All truck restrictions, including those that banned big rigs carrying flammable cargo, were lifted.
Caltrans says daytime traffic along a 1.5-mile stretch between Lamoine and Pollard flat may be limited to one lane while crews continue to repair infrastructure damaged shortly after the fire broke out last week.
The Shasta County Sheriff's Office announced that it was lifting some mandatory evacuation orders along I-5. The orders will remain in place for areas adjacent to two freeway off-ramps that remain closed.
In another milestone of sorts for the blaze, flames advancing on its southwestern edge are close to connecting with the area burned by this summer's Carr Fire, which consumed 230,000 acres. The Delta fire has already reached the perimeter of another large blaze, the Hirz Fire, which has been burning for a month northeast of Redding.
The three fires together have burned 330,000 acres -- more than 500 square miles.
Update, 10:45 a.m. Monday, Sept. 10: Interstate 5 between Redding and Mount Shasta has been reopened, but with travel restricted to one lane in each direction for approximately 17 miles, according to Caltrans in a tweet.
The highway was shut down from 10 miles north of Redding to about 5 miles south of the town of Mount Shasta last Wednesday after the Delta Fire started in the mountains north of Redding. The blaze has now scorched 47,110 acres and is 5 percent contained.
Caltrans said last week the agency will spend about $10 million to fix that stretch of the interstate, work that could take weeks to complete and could likely cause future travel delays.
Update, 11:40 p.m. Sunday, Sept. 9: Fire incident commanders say sunny, warm weather Sunday afternoon allowed the Delta Fire to jump back to life, with the blaze spreading to the south and west.
The extent of the newly burned area was unclear as the estimated acreage -- just under 41,000 acres -- wasn't updated late Sunday. About 2,400 firefighters are working the blaze, which was declared 5 percent contained after part of its eastern edge burned into the footprint of the nearly month-old Hirz Fire.
Although the Delta blaze wasn't as active to the north and northeast, along the Interstate 5 corridor, that key transportation link remains closed into a sixth day.
Caltrans said in a tweet Sunday afternoon that I-5 will remain closed "until further notice." The highway is shut down from 10 miles north of Redding to about 5 miles south of the town of Mount Shasta. The principal -- and often slow -- detour: Highway 299 east from the north end of Redding through Burney, then north and west on Highway 89 to I-5 just outside Mount Shasta.
Crews worked throughout the weekend to remove burned trees that could pose a hazard to traffic and to repair guardrails, fencing, highway signs and other infrastructure damaged as the fire moved up the freeway starting just before 1 p.m. last Wednesday.
Repair crews, firefighters and the general public are all coping with dangerously polluted air.
At one point Sunday, the level of fine particulate matter reached the EPA's "hazardous" level in Redding -- a condition in which all people are warned against any type of outdoor activity. The Redding Record Searchlight reported the particulate reading reached 354, meaning air in the area was the worst in the United States.
Continued unhealthy to hazardous air conditions are expected in the area again on Monday.
Update, 1:50 p.m. Sunday, Sept. 9: There wasn't as much overnight growth for the Delta Fire, burning north of Redding. The fire grew by just over 300 acres to 40,903 acres, with containment now at 5 percent.
Sunday afternoon Caltrans said a stretch of Interstate 5 will remain closed.
Update, 1:44 p.m. Saturday, Sept. 8: The Delta Fire grew overnight to 36,970 acres with zero percent containment.
The California Highway Patrol reiterated Saturday that an approximately 50-mile stretch of Interstate 5 between Redding and Mount Shasta remained closed "to preserve life, property and the safety of all motorists."
In a Facebook post, the CHP also said there is no projected date for reopening.
Caltrans said Friday that conditions along the highway will be reassessed on Sunday.
There will be a public meeting at 6 p.m. today in Lakehead.
Update, 9 p.m. Friday, Sept. 7: Caltrans says Interstate 5 — the main link between California and the Pacific Northwest — will remain closed through the weekend as the Delta Fire continues to burn near the highway.
Smoke from the fire — added to the output from nearby blazes that have been burning for weeks — forced health advisories and school closures in Redding and nearby communities. Firefighting officials said Friday night the fire has burned across 31,325 acres — 49 square miles — since it started early Wednesday afternoon.
Caltrans says the fire is still burning along parts of the interstate and that crews will need to assess damage along the right-of-way — including the presence of thousands of burned trees that could topple into the heavily traveled route.
The fire "has been jumping back and forth across Interstate 5," Don Anderson, deputy director for Caltrans District 2, said Friday afternoon. "... What I've been telling people is we're going to take a good, serious look at it on Sunday, just because there's so much work we have to do in that canyon — and the fire is still active alongside the highway."
Anderson said the agency has identified 3,800 burned trees that need to be removed along the stretch of I-5 where the fire was most intense. He said "a significant number" of those are "hazard trees" alongside the roadway that could pose a threat to traffic.
He said workers are already moving up the closed road removing the hazard trees, a job he said they may complete by Sunday. Contract crews will take down burned trees that don't pose an imminent threat, a process that could take about two weeks.
Anderson said Caltrans already has a $10 million contract in place to replace damaged guardrails, culverts and signs and repave parts of the roadway compromised by the fire's intense heat. That work can take place after the highway reopens, he said, but will require lane closures that could "hamper" traffic through the area for weeks.
Caltrans data show that an average of about 40,000 vehicles a day, including roughly 6,000 trucks, use the stretch of I-5 shut down by the fire. That traffic has been forced onto other roads — notably Highway 299 and 89, a 120-mile detour to the east on often narrow and twisting two-lane roads.
Dense smoke from the Delta Fire and other fires north of Redding created a choking pall over the city Friday. The air pollution rating for "fine inhalable particles" — particles 2.5 microns in diameter or smaller — was 230 in Redding.
That prompted an alert for "very unhealthy air" in the area — the U.S. Environmental Protection Agency's second-highest alert category and one that triggers an advisory for children, older adults and anyone with lung ailments such as asthma to refrain from all outdoor activity.
The poor air quality prompted half a dozen Redding-area school districts to close late Friday morning or issue appeals to parents to pick up their children.
Update, 8:30 a.m. Friday, Sept. 7: The Delta Fire had burned 24,558 acres as of early Friday, with zero percent containment. Interstate 5 is still closed for about 50 miles from just north of Shasta Lake to just south of Mount Shasta. The Shasta County Sheriff's Office advises that the main detour — Highway 299 through Burney, and Highway 89 to Mount Shasta — was subject to gridlock conditions.
Original post, last updated 5 p.m. Thursday, Sept. 6:
A rapidly spreading wildfire in the mountains north of Redding has forced the closure of Interstate 5 and prompted evacuation orders for those living in the sparsely populated area along the upper Sacramento River.
The Delta Fire broke out early Wednesday afternoon near the Vollmers exit from I-5, about 25 miles north of downtown Redding and 20 miles south of the town of Dunsmuir.
On Thursday afternoon, officials said 45 miles of Interstate 5 will remain closed until at least Friday morning.
By early Thursday, the fire had burned 15,294 acres with zero percent containment. The fire is being driven through a densely forested area of the Shasta-Trinity National Forest by hot, dry, windy conditions.
The Shasta County Sheriff's Office ordered evacuations from the community of Lakehead, on the northern end of Shasta Lake, north to the Siskiyou County line — a stretch of about 20 miles. An evacuation advisory was issued for Dunsmuir, with officials in the town of 2,300 telling residents to be prepared to leave.
The rapid spread of the fire Wednesday afternoon caught those traveling along I-5 by surprise. An unknown number of big rigs were abandoned along the highway and burned.
"There's vehicles scattered all over," Brandon Vaccaro, a public information officer for the Delta Fire, told the Redding Record-Searchlight. "Whatever occurred here was probably pretty ugly for a while."
Early Thursday afternoon, 50 miles of I-5 remained closed between the Fawndale exit north of Redding to Mott Avenue, 4 miles south of the town of Mount Shasta.
The closure of the main route between California and the Pacific Northwest forced traffic to attempt a laborious detour, northeast on Highway 299 through the town of Burney, then back west on Highway 89, which meets I-5 just outside Mount Shasta.
That detour route, over about 120 miles of often twisting two-lane roads, was jammed with traffic in both directions by early Thursday afternoon.
The Delta blaze also disrupted freight and service on the Union Pacific's mainline, which runs along the Sacramento River canyon through the fire area. Both freight traffic and Amtrak's Coast Starlight, which runs between Los Angeles and Seattle, were suffering major delays.
The Delta Fire comes just days after the 230,000-acre Carr Fire was declared 100 percent contained. Another large blaze, the Hirz Fire, has burned about 45,000 acres over the last three weeks in the mountains just east of the Delta Fire.
California's firefighting agency is about to exceed its budget and needs $234 million more, Cal Fire director Ken Pimlott said in a letter to lawmakers Thursday.
The agency spent $432 million through the end of August and had only about $11 million left, Pimlott wrote. Cal Fire would use some of the money to add firefighters and helicopters, he said.
This post includes reporting by The Associated Press.