Wash. Rev. Code § 78.60.130
Every operator who engages in the drilling, redrilling, or deepening of any well or core hole shall file with the department a reasonable bond or bonds with good and sufficient surety, or the equivalent thereof, acceptable to the department, conditioned on compliance with the provisions of this chapter and all rules and permit conditions adopted pursuant to this chapter. This performance bond shall be executed in favor of and approved by the department.
In lieu of a bond the operator may file with the department a cash deposit, negotiable securities acceptable to the department, or an assignment of a savings account in a Washington bank on an assignment form prescribed by the department. The department, in its discretion, may accept a single surety or security arrangement covering more than one well or core hole.
RCW 78.60.130