As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 8737, ENROUTE GEG - YKM AIR TURNBACK, DURING CRUISE, THE STAB DE-ICE FAIL ILLUMINATED. DUE TO ICING CONDITIONS, THE PILOT DECLARED AN EMERGENCY AND RETURNED TO GEG WITHOUT INCIDENT. MAINTENANCE REMOVED THE EMPENNAGE PRESSURE SWITCH SV001 AND FOUND RESIDUAL MOISTURE WITHIN THE LINES. REMOVED THE WATER FROM THE SWITCH AND ASSOCIATED COMPONENTS AND REINSTALLED THE SWITCH. OPS CHECK GOOD.