Physical Characteristics of Argyle Creek
     The San Juan Islands experience a twice daily tidal cycle, where coastal areas each day experience water depth changes as two tidal highs and two tidal lows.  Each pair of highs or lows is not necessarily equal in height, but the rise and fall follows a consistent pattern.  A typical tidal pattern in the San Juan Islands can be traced along the red line in the graph below, starting at the end of section A: the tide first reaches a "high" high tide (referred to as a high-high), followed by a high-low, a low-high, and a low-low.  This tidal pattern results in Argyle creek draining and filling twice a day, as partly reflected by a somewhat complicated pattern of temperature change within the creek.  Section A of the graph shows the longest drain time that Argyle experiences, about 14 hours in duration.  The water drain corresponds to a large temperature increase of about 9 degrees C. The temperature then rapidly decreases as cold ocean water (about 10 degrees C) flows back into the lagoon.  The temperature plateaus, labeled B, indicate the short drain and fill time between the high-high and the high-low.
As Argyle Creek drains, it never runs dry. The lowest part of the creek is about 5 feet above sea level (5 ft. above the average daily low-lows for the year 2000), and at low tides water depths in Argyle Creek measure about 12-20 cm along the thalweg.  The creek bed at Argyle is composed of glacially derived sediments, ranging in size from clay to boulders.  The dominant sediments are smaller smooth pebbles and larger rough cobbles, along with dead clam and barnacle shells, and live oyster and barnacle shells.