Wash. Rev. Code § 36.120.120
The regional transportation investment district, by resolution, shall designate a person having experience in financial or fiscal matters as treasurer of the district. The district may designate the treasurer of a county within which the district is located to act as its treasurer. Such a treasurer has all of the powers, responsibilities, and duties the county treasurer has related to investing surplus funds. The district shall require a bond with a surety company authorized to do business in this state in an amount and under the terms and conditions the district, by resolution, from time to time finds will protect the district against loss. The district shall pay the premium on the bond.
In addition to the account established in RCW 36.120.200, the treasurer may establish a special account, into which may be paid district funds. The treasurer may disburse district funds only on warrants issued by the district upon orders or vouchers approved by the district.
If the treasurer of the district is the treasurer of a county, all district funds must be deposited with a county depositary under the same restrictions, contracts, and security as provided for county depositaries. If the treasurer of the district is some other person, all funds must be deposited in a bank or banks authorized to do business in this state qualified for insured deposits under any federal deposit insurance act as the district, by resolution, designates.
The district may provide and require a reasonable bond of any other person handling moneys or securities of the district, but the district shall pay the premium on the bond.
RCW 36.120.120