SDCL § 32-2-10: Compensation--Longevity pay.

The compensation of each agent, patrolman, and employee of the Division of Highway Patrol is set by the Department of Public Safety. Any employee who has worked five years is entitled to longevity compensation each month equal to four dollars for each year of all continuous service up to a maximum of twenty-five years. The longevity compensation may not be affected by any other compensation and classification plan except that the secretary of public safety shall distribute the longevity compensation in the same manner and form as prescribed for other state employees in § 3-8-6.