debt collection procedures in WA state, where do i file debt collection lawsuit

My answer is based on Michigan law but most states have similar provisions regarding your question. The courts have state wide subject mattter jursidiction. So you can probably file in your local county but the court may reject or transfer the case to the court in the defendant's county of residence on the basis that venue (where the appropriate court is located) is proper in the county of the defendant's residence. In some states the courts view venue as a waivable issue and make the defendant raise the issue. You should consult with local counsel for advice specific to your location.