health department question

there is a local seattle business operating with extremely disgusting and unsafe sanitary procedures (I worked there very briefly) and I am wanting to report them to the health department. I have video and photo evidence, but wish to remain anonymous. I’m having a tough time navigating the websites and choosing the best way to go forward. is it recommended to submit a report through the king county department of health, or the washington state department of health? or both? the unsanitary practices are also spread out across multiple locations, so I’m wondering if I need to submit multiple reports. does anyone have experience with this? tia!