King County's 1996/1997 Beach Assessment

Point Wells, Shoreline

Site Description

The beach is located at the northern-most point in King County. The Richmond Beach pump station (formerly a wastewater treatment plant) is located across the railroad tracks to the east. This beach is one of those studied by Thom and Armstrong in the 1970s. A deactivated storage facility for petroleum products adjoins the beach on the north side. The eastern edge of the upper beach is protected by a rip-rap sea wall and the southern edge with a concrete one. The beach is steep down to the 3 foot level and then it becomes a large sand flat. Most of the lower beach is very sandy but there are a few patches of gravel and cobbles.

There were three sand flats, which probably migrate with seasonal wave impacts. The largest patch of suitable substrate for hardshell clams (littleneck and butter clams) was the ridge at the north end of the beach. There was another patch a short distance north of the middle and a third near the south end of the beach. In all three locations, much of the rock appears to have been crushed, indicating that these substrates are artificial.

Invertebrates

Thirty-one (31) species were identified on this beach, the fourth lowest diversity of all the beaches surveyed. The biota are primarily burrowers or animals which are present only when the tide is high and not observable to our surveyors.

Limpets
Plate Limpet	Acmaea scutum
Variegated Limpet	Acmaea persona
Finger Limpet	Acmaea digitalis
Snails
Emarginate dogwinkle	Nucella emarginata
Moon Snail	Polinices lewisi
Chitons
Lined Chiton	Tonicella lineata
Mossy Chiton	Mopalia mucosa
Bivalves
Native Littleneck	Protothaca staminea
Butter Clam	Saxidomus gigantea
Cockle	Clinocardium nutalli
Horse Clam	Tresus sp.
Sand Clam	Macoma secta
Inconspicuous Macoma	Macoma inconspicua
Modest Tellin	Tellina modesta
Bay Mussel	Mytilus edulis
Jingle Shell	Posodesmus cepio
Sea Slugs
Rough Mantled Doris	Onchidoris bilamellata
Sea Stars
Mottled Star	Evasterias troschelli
Barnacles
Small Acorn Barnacle	Chthanalus dalli
Thatched Barnacle	Balanus cariosus
Crabs
Purple Shore Crab	Hemigrapsus nudus
Red rock crab	Cancer productus
Pygmy Rock Crab	Cancer oregonensis
Graceful Crab	Cancer gracilis
Shrimp
California green shrimp	Hippolyte californiensis
Hermit crabs
Hairy hermit	Pagurus hirsutiusculus
Anemones
Colonial anemone	Cribrina elegantisima
Hydroids
Segmented worms
Shellbinder worm	Thelepus crispus
Scale worm	Halosydna sp.
Tube worms
Calcareous tubeworm	Serpula vermicularius
Flatworms
Small speckled	Freemania sp.

Clams

There does not appear to be a well defined clam band on this beach as are found on most of the other beaches, but there are a few patches of gravel and cobbles which support horse clams, butter clams, littleneck clams, bent nose and Macoma irus (inconspicuous macomas). Sand macomas can be found on some of the sand flats. Both numerically and by biomass, the most productive area was the ridge at the north end. Eighteen holes total were dug at three locations, but only thirteen contained one or more clams. One hundred and eighty-two (182) clams, weighing 560 grams, were collected. The average weight per clam of 3.1 grams and the square foot estimate of 463.1 grams were both the third lowest for a beach. The population density of 14 clams per square foot was in the mid-range.

Littleneck and butter clams dominated the clam population, both by number and by weight. Numerically, the littlenecks and butter clams comprised 30% and 39% of the total population, respectively. Their portions of the biomass were 53% for littlenecks and 31% for butter clams. Littlenecks, cockles and macomas were about half the size of the average for all beaches and the butter clams were about one tenth the average.

Check out the following graphs for more information about the clam population:
Numeric composition of clam population
Weight composition of clam population
Numeric distribution of clam population
Biomass distribution of clam population

No manila clams were collected. Only five of 51 littlenecks, or 10%, were of legal size for recreational harvesters and only two of 70, or 3%, of the butter clams were legal. In both cases, those percentages were the fourth lowest of the beaches surveyed. Horse clams can be found in the few patches of sand and gravel but they are so scattered that they escaped collection.

Algae

There was no formal algae survey conducted but it was observed that larger species of Desmerestia, Costaria and Sargassum were present where cobbles and boulders were present in the subtidal area. Sea lettuce was attached to most of the rocks on the ridge to the north.

Other

Various shorebirds and gulls were sited, including the following species: western gull, Bonaparte's gull, herring gull, western grebe, Arctic tern and great blue heron.

Use

On all sample dates and days on which mapping activities were conducted, harvesters were observed if the low tide level was 0 foot or lower. The ridge at the north end is riddled with craters from the clam digging. Questionable harvesting practices were observed. Volunteers and staff helped a large group cull and release the undersized crabs they had collected. They helped another group correctly identity the horse clams that they thought were geoducks.

There are quite a few craters here left by clam diggers. Beachcombers and clam diggers were observed on nearly every low tide event for which we were present. Even without the harvesting pressure, the entire beach would not be very productive because of the substrate, although the three gravelly patches would support more biomass.

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Updated: 11/02/98