182 
BULLETIN OF THE BUREAU OF FISHERIES 
The average tidal range at the Shelton Dock is 10.6 feet. To calculate the 
volume of water at high tide, it was assumed that the tide land of the bay would 
have an average depth, between zero tide level and high tide, of one-half this range, 
or 5.3 feet. The 613 acres of tide land, therefore, would be covered with 3,259 acre- 
feet of water. The 1,015 acres not bare at low tide would have an additional volume 
of 10,759 acre-feet at high tide and a total of 23,149 acre-feet. There is, therefore, 
an indicated volume of 26,411 acre-feet in the bay at high tide. Since there are, of 
necessity, irregularities in the bottom which can not be measured in calculations, 
the volume at high tide is considered to be 26,000 acre-feet and 12,000 acre-feet at 
low tide. Therefore, on the average, 14,000 acre-feet of water leave Oakland Bay 
at each tide. All of this water could be contained in Hammersley Inlet and might 
return with the tide, but such is not the case. On the smaller tides most of the water 
returns, only a small portion being lost by mixing with the waters in the eddies. 
(Fig. 43.) 
An effort was made to estimate the volume of water which is lost from Oakland 
Bay by tidal action. Hammersley Inlet receives an average of 14,000 acre-feet of 
water from Oakland Bay on the ebb tide and returns a similar amount on the flood 
tide. If the same water which leaves Oakland Bay does not return, it is lost by 
mixing with Hammersley Inlet water or by entering Pickering Passage where it is 
carried into Case Inlet and does not return on the ebb tide, the most of which may 
come through Squaxin Passage. (Fig. 43.) In other words, the tidal action in 
Hammersley Inlet is an oscillating movement in which water moves from Oakland 
Bay into Hammersley Inlet and back again. Some consideration must be given to 
the loss of Oakland Bay water by mixing in Hammersley Inlet. Each cove and 
stream mouth was observed on two to five occasions, and it was estimated that they 
retained less than 50 acre-feet of water at high tide which may have been derived 
from Oakland Bay. Exclusive of this amount, Oakland Bay water which does not 
leave Hammersley Inlet returns on the ebb tide to the bay. We must also bear in 
mind that the principal discharge of the sulphite liquor is at the lower end of Ham- 
mersley Inlet; hence the water which replaces that lost into Hammersley Inlet is 
itself polluted. 
An attempt was made to determine when ebb tide currents would carry water 
from Oakland Bay through Hammersley Inlet into Pickering Passage. It was found 
that on a normal ebb tide preceding low water recorded as — 1.3 feet at Seattle, water 
from Oakland Bay may reach Pickering Passage. By drifting in a skiff down Ham- 
mersley Inlet and maintaining a position as nearly as possible in the swiftest current, 
it was found that the boat did not reach the passage before low water. It is recognized 
that a certain inaccuracy is introduced by the use of a boat for this purpose. How- 
ever, the work was carried out on a calm day when air resistance would be at a mini- 
mum and the drift was with the prevailing air currents. These errors were more 
than counterbalanced by keeping the boat in the swift current and out of the eddies. 
Floating debris drifting at random did not cover an equal distance. There are usually 
about 50 tides a year which are lower than —1.3 feet (reference station, Seattle); 
these average —2.5 feet in height. On such a tide it was found that by starting at 
the entrance of Oakland Bay with the beginning of the ebb and drifting in the strong- 
est part of the surface current, one could arrive at the lower end of Pickering Passage 
two hours before low water. 
At approximately the time when the water from Oakland Bay could have reached 
Pickering Passage, as estimated in the manner just described, the rate of the flow of 
