Fires threaten San Fran reservoir
25 August 2013 Last updated at 09:19 BST
After declaring a state of emergency in California up to 4,000 firefighters are still battling a fast-moving wildfire on the edge of Yosemite National Park.
Officials say the fires are also threatening to pollute a reservoir which supplies San Francisco with 85 per cent of its water.
Alastair Leithead reports from Los Angeles.