The park contains a rare ecosystem where a freshwater stream estuary interacts directly with the saltwater environment of the bay.
During low tide, the receding water exposes nearly a mile of tidelands, which are historically significant for local indigenous clamming and shellfish harvesting.
The area is part of the Pacific Flyway, making it a critical observation point for migratory birds such as loons, grebes, and brant geese.
The park's Terwilliger Creek is monitored for salmonid restoration success to maintain local aquatic biodiversity.
The bay is one of the few places in the region where the water warms significantly during summer months due to the shallow depth and protected geography.
Birch Bay State Park encompasses 194 acres along the northern Washington coastline, featuring 8,255 feet of saltwater shoreline on Birch Bay. The park is characterized by a long, stony beach that offers unobstructed views across the bay toward the San Juan Islands and the Canadian Gulf Islands. It features an extensive year-round campground with 147 standard sites and 20 partial-utility sites. Terrestrial habitat includes a significant second-growth forest of cedar, hemlock, and Douglas fir. Terwilliger Creek flows through the park and serves as a vital spawning habitat for local salmon species. The area is a recognized migration stopover for diverse bird populations, particularly waterfowl and shorebirds. Facilities include multiple picnic shelters, a boat launch, and miles of hiking trails. The bay's shallow, protected waters provide a calm environment for swimming and non-motorized boating.
The elevated boardwalk and viewing platforms overlooking the bay at sunset.
Wear water shoes or sturdy sandals to comfortably navigate the rocky, oyster-shell-covered beach.
Check tide charts before visiting to ensure you are present during low tide, which is the best time for beachcombing and mudflat exploration.
Bring binoculars to take advantage of the high density of migratory waterfowl visible from the shoreline.
Attempting to walk on the beach in flip-flops or bare feet due to the sharp oyster shells and uneven stones.
Practice Leave No Trace principles; do not remove shells or rocks from the beach; keep dogs on a leash at all times.
