No person shall drive a motor vehicle within any state park area at a speed greater than is reasonable and prudent, having due regard for the traffic on, and the surface and width of the road, and in no event at a speed which endangers the safety of persons, property, or wildlife: Provided, however, That in no event shall a vehicle be driven at a speed greater than 15 miles per hour in camp, picnic, utility, or headquarters areas, or in areas of general public assemblage: And provided further, That in no event shall a vehicle be driven at a speed greater than 25 miles per hour in any other area except designated ATV areas and trails. In no event shall a person operate a vehicle in a designated ATV area or trail at a speed which is not reasonable and prudent for the activity and existing conditions. The commission, however, upon finding that the safety of persons and the condition of the road and the traffic thereon so warrants, may establish lower speed limits and shall post the same in the area where so established. Except as provided in WAC 352-20-070, any violation of this section is an infraction under chapter 7.84 RCW.