WA state real estate law, keeping neighbor off property

The statute of limitations for bringing an action in ejectment is 7 years if the encroaching is party is doing so "under color of title"; e.g., is paying the property taxes; otherwise it is 10 years. It sounds like the 10 year statue of limitations applies in your case. If you fail to either bring legal action or physically block the neighbor's access (such as with a fence) within the 10 year period, then the neighbor becomes the owner of the area on which he encroached. This is called the doctrine of adverse possession.

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