Yes. It's the law.
Calling 811 two business days before you begin digging alerts utilities to come out and mark their buried lines from the street to your property line at no cost to you.
Be aware that many buried utility lines under your property belong to you. Locating buried utility lines that you own must be performed by a private company.
Puget Sound Energy Customers: Call 811
Snohomish County PUD Customers: Call 800-424-5555
Learn more about Washington's Call Before You Dig Law.