Washington County Administration Washington County Administration Search | Advanced Search | New Members | Coupons and Discounts | All Categories Government & Education >> GOVERNMENT AGENCIES Washington County Administration 155 N 1st Ave, #300, MS-21Hillsboro, OR 97124 | map | directions (503) 846-8685 | fax: (503) 846-4545 Visit Site Send a message to: Washington County Administration Your Name: Your Email: Subject: Message: (Date: 4/20/2024) If your business isn't here, contact us today to get listed!