UPDATE: The Silver Creek Fire is estimated at 27 acres and is 35 percent contained as of Monday afternoon.
The fire at Silver Falls State Park was estimated to have burned 19 acres as of Saturday, but Bobbi Doan, a spokesperson for the Oregon Department of Forestry, said that the larger area estimate is due to improved mapping.
There are approximately 125 personnel and three helicopters currently engaged in fighting the fire.
The 214 Trailhead and several back-country trails, the Howard Creek horse camp and day-use area, the youth camp and Ranches remain closed.
More than a day after smoke was first noticed in Silver Falls State Park, fire crews were finally able to reach the blaze Saturday after having cut through brush up to 3 feet deep on steep terrain in a previously unreachable area of the forest.
Consistent bombardment from air tankers and helicopters bought the ground crews time to get to the Silver Creek Fire, with more than 60,000 gallons of water and fire retardant dropped around the blaze.
That helped keep the fire at between 12 and 15 acres Saturday morning. By the evening, the fire had grown to 19 acres, Oregon Department of Forestry officials said via Twitter. It was 20 percent contained.
Photos: Fire at Silver Falls State Park
But the same thick growth that crews had to cut through also limited the effectiveness of the water and retardant.
"Planes have to drop a full load all at once just to get through the canopy," said Brent O'Nion, incident commander for the Silver Creek Fire. Even then, he said, the tall underbrush keeps the retardant from reaching the ground, allowing the fire to creep along beneath.
In addition, because the fire is burning along Silver Creek, use of the retardant is somewhat restricted. Environmental regulations require retardant not be used with 300 feet of a creek; O'Nion said his crews keep it 400 to 600 feet away to be extra careful.
This effectively meant that crews could only fight the fire from one side.
More than 100 personnel, a handful of planes and helicopters and several trucks and other pieces of large machinery are working to extinguish the blaze, which is burning in the southeastern corner of Oregon's largest state park.
"It's small, but it has a lot of potential," O'Nion said.
If that kind of fuel were to catch in a significant way, or weather conditions took a turn for the worse with high winds and even lower humidity, it could spell trouble.
That's part of the reason this fire has gotten the amount of attention it has.
"This is the priority for the agency," said Bobbi Doan, spokeswoman for the Oregon Department of Forestry.
While a number of trails and camps were closed, the majority of the park remained open Saturday, though officials warned that there would be abundant firefighter equipment and aircraft. At the historic main lodge, the annual Historic Silver Falls celebration went ahead as planned.
Hundreds of families drove in, filling the grounds with picnics, children playing, vendors, and a four-piece band played country music.
Tom Winterrowd, dressed in suspenders, a bowtie and an English driving cap, wasn't worried about the nearby fire, and didn't hear of anyone who was. Winterrowd was there for the antique car display, proudly displaying his 1929 Model A AA commercial truck along with a dozen other classic vehicles.
"If there was a big concern, I assume they would let us know," Winterrowd said. "It's just a reminder we all have to be careful because it's so dry up here."
The Howard Creek Horse Camp was closed and is being used as a staging area for firefighting operations.
Several backcountry trails and 214 Trailhead were closed, and 142 people were evacuated from a YMCA summer camp Friday as the fire burned a mile away.
None of the waterfall trails are closed. However, officials said those concerned about traveling to the area should call 503-873-8681 if they had questions. Officials said Saturday this line has experienced a deluge of calls.
Smoke was first reported late in the evening on Thursday, July 12, officials said.
Silver Falls State Park is the largest state park in Oregon at 9,200 acres southeast of Silverton. The park has 35 miles of backcountry trails that are used for hiking, mountain biking and horseback riding.
It is most famous for the Trail of Ten Falls, a 7.2-mile forested trek past 10 waterfalls including a 177-foot cascade where hikers can walk behind the falls.
The park is also an economic booster. A study recently found the 1.4 million visitors annually contributed $58.4 million to the local economy.