They are using two types of delivery systems. The bucket carries 600 gallons of water. It is good for spot drops on exact spots. The chopper pilot told me that they are hard to control as they swing around on the end of the cable. They have to hover to drop and that is not easy next to the steep cliffs and the winds whirling around the fire. The other system uses a siphon into a tank inside the chopper. Don't know how many gallons but a lot more than the 600 of the bucket. This system can spray over a wider area and the chopper does not have to hover.
Got a PM asking about what gear I am using. I have been shooting with two cameras, a Nikon D850 and my backup camera a D750. Both are full frame DSLRs The D850 is 45.7 megapixels and the D750 about 24. The lens I used the most was a Nikon 200-500. I do not shoot JPEG, I shoot uncompressed RAW and make JPEGs in Photoshop CC.