The Coast Guard will enforce 13 safety zones for annual firework displays in the Captain of the Port, Sector Puget Sound area of responsibility to provide for the safety of life on navigable waterways during these events. Our regulation for marine events within the Thirteenth Coast Guard District identifies the regulated area for these events. During the enforcement periods, the operator of any vessel in the regulated area must comply with directions form the Patrol Commander or any Official Patrol displaying a Coast Guard ensign.
Source: Federal Register USCG
Link: Safety Zones; Annual Fireworks Displays Within the Puget Sound