(1) The department shall assess premiums, under the provisions of this section, for certain horse racing employments licensed in accordance with chapter 67.16 RCW. This premium assessment shall be for the purpose of providing industrial insurance coverage for employees of trainers licensed under chapter 67.16 RCW, including but not limited to exercise riders, pony riders, and grooms, and including all on or off track employment. The department may adopt rules under chapter 34.05 RCW to carry out the purposes of this section, including rules providing for alternative reporting periods and payment due dates for coverage under this section. The department rules shall ensure that no licensee licensed prior to May 13, 1989, shall pay more than the assessment fixed at the basic manual rate.

(2) The department shall compute industrial insurance premium rates and these premiums may be assessed at the time of each issuance or renewal of the license for owners, trainers, and grooms in amounts established by department rule for coverage under this section. Premium assessments shall be determined in accordance with the requirements of this title, except that assessments shall not be experience rated and shall be fixed at the basic manual rate. However, rates may vary according to the risk insured, as determined according to rules adopted by the department and the Washington horse racing commission.

(3) For the purposes of paying premiums and assessments under this section and making reports under this title, individuals licensed as trainers by the Washington horse racing commission shall be considered employers. The premium assessment for a groom shall be paid by the trainer responsible for hiring the groom and is payable as required by the Washington horse racing commission.

(4) The fee to be assessed on owner licenses as required by this section shall not exceed one hundred fifty dollars. However, those owners having less than a full ownership in a horse or horses shall pay a percentage of the required license fee that is equal to the total percentage of the ownership that the owner has in the horse or horses. In no event shall an owner having an ownership percentage in more than one horse pay more than a one hundred fifty-dollar license fee. The assessment on each owner's license shall not imply that an owner is an employer, but shall be required as part of the privilege of holding an owner's license.

(5) Premium assessments under this section shall be collected by the Washington horse racing commission and deposited in the industrial insurance trust funds as provided under department rules.