I have been in contact with the county road department, and found out that the spill originally ocurred 5 days prior to my accident. The Sheriff requested the State DOT to respond, and they spread "kitty litter" to absorb the fuel, and the State DOT then requested the county road department to spread some gravel. The county road department also stated since the spill ocurred on a State road, the State DOT would have been responsible for posting the warning signs.
So I called the State DOT, and they said they would send me a complaint form, and to list all the damaged equipment with documentation of replacement costs. They stated they will have an investigator contact me, and they may have to replace my gear and equipment if no warning signs had been placed. This will be documented by a witness and hopefully the Washington State trooper's report, which I will obtain.
BTW, the witness who lives on the corner of the intersection where the accident occurred stated that the gravel was cleaned up within an hour after I had left the scene...