You must have a snowmobile decal in order to operate your snowmobile in Oregon. This applies to all land, including your own, unless you are exempt under ORS 821.090. You can get a snowmobile decal through the Oregon Driver & Motor Vehicle Services Department. You can also apply for a trip permit if you are a non-resident and your home state does not require snowmobile registration. You can get more information on trip permits at theOregon Driver & Motor Vehicle services website.
Check out these Hermiston, OR ATV/OHV resources: