The average corporal salary at Grant County was $129,836 , which is 6 percent lower than the average salary for this job in Washington, but 36 percent higher than the national average for this job . Corporal salaries at Grant County typically range from $120,658 to $144,760 (25th to 75th percentile). The highest reported corporal salary was $159,328. There are 6 employees at Grant County with the job title corporal.