California fire officials said Monday morning that containment of the fast-moving wildfire near Yosemite National Park jumped to 15 percent, an 8-percentage point increase over its status on Sunday night. The announcement came four days after Gov. Jerry Brown declared a state of emergency in the area due to the threat the fire poses to water and electrical power.

The wildfire, dubbed the Rim Fire, has been raging for nine days. It has burned more than 224 square miles of land, including over 15,000 acres within Yosemite National Park. As of Monday, the wildfire continued to progress towards Yosemite’s Hetch Hetchy Reservoir, which is the primary water supply for the San Francisco Bay Area.

According to the Associated Press, the fire has already begun to send ash into the reservoir, but not enough to reach intake pumps yet. Tyrone Jue, a spokesman for the San Francisco Public Utilities Commission, said the fire had not caused any interruptions or damaged the quality of the water supply.

"Obviously, it's the water supply of the city of San Francisco, so we're paying a lot of attention to that," Glen Stratton, an operations section chief working on the fire, told the news network.

Media outlets reported on Monday morning that the fire was approximately five miles from the reservoir, Agence Free-Press reported. In preparation, crews rushed to move water from Hetch Hetchy into other local reservoirs before the supply became contaminated. Public Utilities Commission General Manager Harlan Kelly Jr. said a recent expensive upgrade to the city’s piping system had also helped to expedite the process.

Kelly said San Francisco currently has a six-month backup water supply. Brown’s emergency declaration on Thursday, which referenced “conditions of extreme peril,” also permitted the city to spend $600,000 on replacement electricity, Bloomberg reported.

Despite federal aid and the efforts of more than 3,678 firefighters working on the fire, officials have said fire crews have faced brutal obstacles at nearly every turn; among them thick brush, high winds and inaccessible terrain.

"This fire has continued to pose every challenge that there can be on a fire," Daniel Berlant, a California Department of Forestry and Fire Protection spokesman, said. “Our containment doubled overnight, but there's still a lot of work to be done.”

Firefighters hoped to gain an advantage on the fire on Monday, but Berlant said that they expected wind speeds to increase again. An update on InciWeb on Monday stated, “Access and difficult terrain remain concerns for crews and equipment. Good progress was made with constructing and securing lines along the northwest and northern portions of the fire. Good progress is also being achieved with construction of contingency lines along the western edge of the fire.”

Despite the fire raging to the west, most of Yosemite remained open on Monday, with some temporary closures.