King County's Beach Assessment

Dash Point State Park, Federal Way

Site Description

The beach forms the northern boundary of Dash Point State Park located south of the city of Federal Way. The beach is very flat and can be 1,000 feet wide at low tide. The beach is comprised mainly of sand with a few patches of gravel or mud. The west end of the beach, where it is widest, is a huge alluvial fan deposited by a small stream that runs through the park. The stream flows through a steep ravine into which mud slides have become more frequent with increasing development. Local residents stated that the upper beach used to be comprised of gravel and cobbles but that they have been buried after flood events in recent years. The beach is bounded by clay bluffs in many places, and curved trees as well as toppled trees indicate that erosion is actively occurring.

Invertebrates

Thirty-two species (about the median number for all of the beaches combined) of invertebrates were identified on this beach. This number was surprising, given the limited diversity of habitat.

The presence of eelgrass accounts for much of the diversity of invertebrates. An extensive eelgrass bed provided habitat for geoducks, large cockles, jackknife clams, moon snails, orange peel sea slugs (bright orange and a foot or more long) and bamboo worms. Horse clams were common in the eelgrass bed and on the middle beach as well. The striped nudibranch, which favor eelgrass beds, were common place.

Marine life is scarce on the upper beach except for colonies of ghost shrimp and sand clams. A few pink Baltic macomas and soft-shell clams have been found there as well.

Limpets
Plate Limpet	Acmaea scutum
Finger Limpet	Acmaea digitalis
Snails
Sitka Periwinkl	Litorina sitchana
Moon Snail	Polinices lewisi
Bivalves
Native Littleneck	Protothaca staminea
Manila Clam	Tapes japonica
Butter Clam	Saxidomus gigantea
Cockle	Clinocardium nutalli
Softshell	Mya arenaria
Horse Clam	Tresus sp
Sand Clam	Macoma secta
Bent Nose Macoma	Macoma nasuta
Baltic Macoma	Macoma balthica
Jackknife Clam	Solen sicarius
Common Piddock	Penitella penita
Bay Mussel	Mytilus edulis
Horse Mussel	Modiolus rectus
Geoduck	Panope generosa
Native oyster	Ostrea luridea
Sea Slugs
Trochni	Tochuina tetraquetra
Striped Nudibranch	Pleurophyllidia californica
Urchin
Sand Dollar	Dendraster excentricus
Barnacles
Acorn Barnacle	Balanus glandula
Small Acorn Barnacle	Chthanalus dalli
Thatched Barnacle	Balanus cariosus
Crabs
Northern kelp crab	Pugettia producta
Dungeness crab	Cancer magister
Ghost shrimp
Bay ghost shrimp	Neotrypaea californiensis
Anemones
Colonial anemone	Cribrina elegantisima
Hydroids
Tube worms
Plume worm	Eudistylia polymorpha
Parchment tube worm	Chaetopterus variopodutus
Jointed tube worm	Telepsavis sp.
Isopods
Beach Cockroach	Ligia pallasii

Clams

The scarcity of clams at this beach rendered the sampling protocol inappropriate. It was designed for sampling hard shelled clams. There were virtually none at this beach because the substrate was too uniformly sandy to support them.

Nearly all of the clams found during the survey were sand macomas. While they are common on this beach, they do not seem to form dense colonies as the Manila and little-neck clams do. Most of the clams were found toward the east end of the beach. This beach appears to be an excellent habitat for geoducks and might benefit from planting. We found a few cockles and macomas in the sand flats. Near the dock, there is a colony of horse clams. They are in the gravel and cobbles that are overlaid by approximately six inches of sand.

Seaweed

Only nine species of algae were recorded on this beach, including eelgrass. This low diversity is due primarily to there being little substrate, such as large rocks, for attachment. Surf could also be a factor. An extensive eelgrass bed was located along the entire beach at about the +1 foot and lower.

Green (Chlorophyceae)

Enteromorpha intestinalis

Enteromorpha plumosa

Enteromorpha. linza

Ulva lactuca

Brown (Phaeophyceae)

Fucus sp

Punctaria hesperia

Pylaiella littoralis

Polysiphonia collinsii

Red (Rhodophyceae)

Porphyra perforara

Other

This beach has at least one "resident" great blue heron. The state park ranger stated that sea lions haul out for the night on this beach.

Use

This long, flat sandy beach is used mainly for family recreation such as beachcombing and swimming. Children and adults wade and swim on this beach as the sand warms the water on an incoming tide. The beach is not often used for harvesting as there is little here to be harvested.

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Updated: 11/02/98